THE DEPARTMENT OF ASTRONOMY
THE UNIVERSITY OF WISCONSIN-MADISON
This report covers the period October 1, 1996 -September 30, 1997. It does not include most of the astrophysics research carried out in the Department of Physics. The acronym WIYN refers to the Wisconsin-Indiana-Yale-National Optical Astronomy Observatories 3.5-meter telescope on Kitt Peak, AZ; HST to the Hubble Space Telescope; WUPPE to the Wisconsin Ultraviolet Photo-Polarimetry Experiment flown on the ASTRO-1 and ASTRO-2 missions aboard the NASA Shuttle; PBO to the Pine Bluff Observatory near Madison, with its 0.9m telescope.
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Matthew Bershady joined the faculty as Assistant Professor. He was previously Assistant Professor at the Pennsylvania State University. His interests include distant galaxy kinematics, image structure, and luminosity functions, as well as instrumentation. Linda Sparke was promoted to the rank of Professor. She spent a sabbatical year at the Kapteyn Laboratory (Groningen) and Mt. Stromlo. The other faculty are Professors Anderson, Cassinelli, Churchwell, Gallagher (Chair), Hoessel, Mathieu, Nordsieck, Reynolds, and Savage, and Assistant Professor Wilcots. Professor Emeriti in frequent contact with the department are Bless, Code, Mathis, and Whitford. Percival has the rank of Scientist.
Stephen Tufte and Mark Quigley joined the staff in postdoctoral research positions. Others on research appointments are Cohen, Harris, Percival, Sawyer (at WIYN), von Hippel (at WIYN), and Wakker. Four postdoctoral researchers resigned: Geoff Fox (to teach in England), Joni Johnson (at New Mexico State University), Menshing Han (to GSFC), and Kenneth Wood (to CfA).
Code continued to serve as the WIYN Observatory Scientist and is spending 1997-98 at NOAO in Tucson, AZ. Churchwell spent the spring semester and part of the summer on sabbatical as a guest of NRAO at the VLA in Socorro, NM. He is the current chair of the Millimeter Array Advisory Committee (MAC) which advises the Director of NRAO on the Millimeter Array project, and was a JILA Fellow in Boulder during part of April 1997. Gallagher was active in the Gemini 8-m telescopes project and led a science working group at the Abingden (UK) instrumentation meeting. Mathieu served as Chair of the Kitt Peak National Observatory Users Committee, as well as the WIYN Board of Directors and Scientific Advisory Committee. Savage ended his three year position as a Councilor of the American Astronomical Society. He continued as a member of NASA' s Origins Subcommittee, which advises NASA on science programs to be pursued as part of their Origins Program. He ended his association with the WIYN Board of Directors; Gallagher was appointed as his replacement. Percival continued his participation in the IAU Working Group on Astronomical Standard's initiative "Standards of Fundamental Astronomy." The goal of this effort is to produce a set of basic software that implement commonly-used formulae and standard models in fundamental astronomy. Mathis spent 6 weeks at UNAM, Mexico City.
Steven Gibson completed the PhD degree with a thesis "Gas and Dust in the Pleiades Reflection Nebula". He is now a Research Associate at the University of Calgary.
Todd Tripp received the Ph.D. degree with a thesis "The Nature of QSO Absorption Lines: Abundances, Physical Conditions, and Environment" involving observational data from HST, WIYN, and the KPNO 4-m telescope. In January, 1997, he joined the research staff in the Department of Astrophysical Sciences in Princeton, NJ, where he is pursuing UV spectroscopic studies with the Space Telescope Imaging Spectrograph.
David Cohen has held a post-doctoral position in both the Fusion Technology Institute (in the Engineering Physics department) and Astronomy during 1996/97. His main areas of interest are hot star winds, X-ray astrophysics, and EUV/X-ray spectroscopy in laboratory and astrophysical settings. In September, 1997, he was promoted to Assistant Scientist with a joint appointment in Engineering Physics and Astronomy.
Ted von Hippel has continued in his position as the McKinney Assistant Scientist stationed at the NOAO headquarters in Tucson, where he supports Wisconsin observers at the WIYN Telescope.
Jerry Acord has accepted a position as a BIMA postdoctoral fellow at the Univ. of Illinois after defending his thesis in October, 1997. Michael Faison is currently at the NRAO in Socorro, NM working with Drs. Miller Goss and Phil Diamond on small scale structure of cold, neutral gas in the interstellar medium using the VLBA and VLA.
A team involving Anderson, Nordsieck, Reynolds, Scherb, Roesler, Harris, Tufte, Woodward, and Mierkiewicz have studied comets Hale-Bopp, Hyakutake, and Wild 2, as well as Jupiter's volcanic moon Io.
Various observations were made on comets:Narrow band images and spectra were obtained with both theWIYN HydraPak and DensePak.Theobservations of Hale-Bopp were among the first that made use the next generation comet filter library, and the HydraPak and DensePak were thefirst observations of their kind ever successfully performed for a comet. (2) With the HPOL instrument at PBO, multiple spectropolarimetric observations of Hale-Bopp were performed over a period of several months. HPOL should open some novel areas for the study of comets,particularly in the area of atomic and molecular resonance polarimetry. (3) On 8 April, 1997, the Wide-Field Imaging Survey Polarimeter (WISP) rocket experiment observed the polarization and spatial distribution of dustcontinuum emission 2800 Å and CI l1657 emission. Theinitial look at this data suggests that the C I l1657 was unpolarized,a completely unexpected and inexplicable result that may require a reevaluation of theory. (4) Over 12 nights of wide field observations were performed on comets Hale-Bopp and Wild 2 were obtained at the Burrell Schmidt . (5) The WHAM Fabry-Perot spectrometer obtained velocity resolved H2O+ l6198 and [O I] l6300 emissions in Hale-Bopp. (6) The McMath-Pierce Telescope and WIYN were used to studyHale-Bopp including interferometric spectroscopy and imaging of H2O+,Ha, Hb, [O I] l6300, and CI l9850 emissions, as well as high resolution spectroscopy with the echelle spectrograph. (7) In March and April the team used an Adaptive Optics system on the Hooker Telescope at Mt. Wilson for the first time on a comet, obtaining spatial resolutions down to0.2" in a series of broadband and cometspecific filters. Data from comet Hyakutake were the first evidence of gas flow interactions between the nucleus of a comet and debris (Harris et al. 1997).
Study of the Jovian system continuedat the McMath-Pierce telescope. A first attempt to observe Jupiter's aurorausing a visible band emission (Ha) was tried in September, 1996, in consort with similar observations using the IUE, HST, and Galileo. Observations of the Io torus (both spectroscopic and imaging) were also performed periodically throughout the year at the McMath-Pierce. Currently narrow band imaging studies of Na I emission near Io's surface using the adaptive optics system at Mt. Wilson are planned.
Between 1996 October and 1997 May, Anderson and colleagues obtained more than 7400 WIYN spectra of Comet Hale-Bopp with both the Hydra and Densepak fiber feeds to the Multi Object Spectrograph. Most were at a resolution of 15,000 in the range 6100 Å — 6400 Å. A sample of the results may be seen at: http://www.astro.wisc.edu/~anderson/HaleBoppMOS.html.
3. Stars and Galactic Structure
Mathieu, Lattanzi (Torino), Zinnecker (Wurzburg) continued an HST Fine Guidance Sensor program to obtain an astrometric orbit of the pre-main-sequence single-lined spectroscopic binary 045251+3016. This three-year program will provide absolute orbits of both stars, thus providing both the orbital inclination and the mass ratio. When combined with the existing spectroscopic orbital elements, precise masses of the stars and the distance to the binary will be obtained. The first observations successfully resolved this 7-yr period binary.
Mathieu, Carr (NRL) and Najita (CfA) continued a program of high-resolution near-infrared spectroscopy (CO fundamental and overtone transitions) in order to explore the circumstellar gas in several young binaries. The program has been expanded to include stars showing evidence for cleared inner regions of their disks, perhaps indicative of planet formation.
Rhode (Wesleyan), Herbst (Wesleyan) and Mathieu began a WIYN study of the radii of pre-main-sequence stars. High resolution WIYN spectra were obtained for a sample of Trapezium stars with known rotation periods. Measurements of vsin i provide a statistical measure of the stellar radii. The preliminary results formed the basis for Rhode's master thesis.
Stassun, Mathieu, Mazeh (Tel Aviv) and Vrba (USNO) continued analysis of a survey for photometric variability of stars within a roughly 1 x 2 degree region centered on the Trapezium. Light curves of about 5000 stars have been completed, producing rotation periods for more than 200 stars. Vrba began near-infrared photometry for this subset. Several eclipsing binary candidates have also been discovered. Analysis of light curves will form the thesis of Stassun.
von Hippel is continuing his work with C. Bailer-Jones (IoA, Cambridge), M. Irwin (RGO, Cambridge), and N. Houk (U. Michigan) to automate visual stellar classification. Three papers on this work (Jones et al. 1997 a ,b, c) have recently been completed. They are using Artificial Neural Network techniques as the basis for their automated classifier. To date 100 of Houk's plates, covering 10% of the southern sky, have been analyzed. This project has demonstrated that automated classifiers can give very good results and are ready for future large-scale surveys. From their data set they have achieved precisions of 0.8 spectral subtypes and approximately 95% of the objects are correctly classified as dwarfs or giants.
Cassinelli and his colleagues have continued working on magnetic fields in the winds of early type stars. Ignace, Cassinelli and Bjorkman have used the wind compressed zone model (Ignace et al. ApJ 1996) for the equatorial outflows from luminous stars, along with equations for the streak lines of magnetic fields in winds to derive three-D models for both the outflows and the magnetic fields. Ignace, Nordsieck and Cassinelli have completed two papers discussing the Hanle effect, which exploits polarization line profiles of resonance lines, mostly in the far-UV region of the spectrum, to estimate the field strength and configuration. The Hanle effect can be used to derive field strengths in the 1 to 1000 Gauss range, while the Zeeman measurements are, for the most part, restricted to determinations of stronger fields. Nordsieck's Far Ultraviolet SpectroPolarimeter (FUSP) rocket experiment has the capability of making the required UV polarization observations.
Ignace and Cassinelli are obtaining Infrared Space Observatory (ISO) observations of Wolf Rayet stars in order to derive the velocity distribution from the line widths of IR recombination lines. According to the Wind Compressed Disk model of Bjorkman and Cassinelli, stars with rather slowly increasing velocities as a function of radius are more likely to have equatorial disks.
The excess EUV flux of e CMa (B2 II) observed by Cassinelli et al. 1995 remains unexplained. In the region 500 to 700 Å the star emits 30 times the flux predicted by model atmospheres, suggesting that the outer atmosphere is 3000 K hotter than predicted. The B 1.5 III-II variable star beta CMa also shows an excess in the 500 to 700 Å region. These are the only two B stars that can be detected by EUVE. If B stars normally possess heated outer atmospheres, they should also show an infrared continuum excess. Cohen and Cassinelli are making ISO observations to see if this is the case. Cassinelli and Walters are considering pulsation-driven shock models to explore what is needed to produce the empirically derived heating.
Cohen, Cassinelli, and MacFarlane completed their study of the X-ray emission around B stars. The emission measures required to explain the X-rays exceed the emission measures expected in stellar winds. Perhaps some of the emission arises from hot magnetically confined regions located near the base of the stellar wind. Cohen, Cassinelli, and Waldron have completed a detailed study of the X-ray emission from t Sco (B0 V). This star has anomalously hard X-ray emission, and constraints on several models are discussed.
Conselice and Cassinelli have begun working on models for the formation of very massive stars. This is based on earlier work on star formation by Wolfire and Cassinelli (1987) but includes the effects of the rotation of the protostar.
Besides working on X-rays from hot stellar winds, Cohen has studied EUV/X-ray spectroscopy in laboratory settings and ORFEUS EUV spectroscopy of e CMa (B2 II). A project with Myron Smith (STScI) involving detailed modeling of helium excitation/ionization in dense slabs in the wind of the Be star l Eri was completed, along with a survey of soft X-ray emission in B stars and an analysis of ASCA X-ray observations of t Sco (B0V).
In collaboration with Nordsieck, R. Pifer, and D. Hines (U of Arizona), Fox analyzed the data collected by WUPPE, PBO, and the McDonald Observatory of the O9 III close binary AO Cas. Also in collaboration with Hines, Fox analyzed observations of the O6 Ia star HD108 from McDonald Observatory.
Gallagher is collaborating with N. King and R. Walterbos (NMSU) in a study of properties of Luminous Blue Variables and related objects in M31 and other nearby galaxies. This project is a part of King's PhD thesis.
Hoffman, Nordsieck, and Fox submitted their paper on spectropolarimetry of Beta Lyrae to the ApJ. Hoffman and Nordsieck continue to investigate this binary with HPOL. In July they began an extensive collaboration with Karen Bjorkman (U. Toledo, Ritter Observatory) to obtain simultaneous spectropolarimetric and high-resolution spectroscopic measurements of Beta Lyrae. They are especially interested in the behavior of the Ha and HeI 5876 emission lines as a function of phase. Hoffman, working with B. Whitney (UW Fusion Technology Institute), began a project involving Monte Carlo radiation transfer modeling of externally-illuminated accretion disks. Such models can help clarify the structure of systems such as Beta Lyrae by distinguishing between the polarimetric behavior of the outgoing radiation in the internally- and externally-illuminated cases.
C. Cool stars; Star Clusters and Galactic Structure
Joni Johnson (now at NMSU) studied WUPPE and WIYN observations of the post-AGB star HR 4049. This prototype of the high-galactic latitude supergiant post-AGB stars showed time-variable polarization that appeared to be arising from Rayleigh scattering in a geometrically thin disk. In addition, the WUPPE polarimetry clearly showed the signature of bipolar structure. Models showed that the disk is optically thin and our viewing angle of the disk changes over the orbital period. The optical depth of the disk varied with the colors of the star as well, lending support to the idea that the photometric and color changes of HR 4049 are caused by an orbiting cloud of dust and gas.
Anderson continued his long-term monitoring of the Ca II H & K chromospheric emission in young clusters. The WIYN Hydra Multi Object Spectrograph is used in echelle mode at a resolution of about 15,000 to record about 200 A around the calcium emission. An unexpectedly low number of stars in NGC 2264 show significant activity. The survey will be extended to other clusters. Weitenbeck & Anderson continued making polarimetric observations in the vicinity of the young Galactic cluster NGC1502 as a long term project of studying the ISM in that direction.
Dolan and Mathieu continued to acquire high-precision stellar radial velocities with the WIYN Multi-Object Spectrograph. As part of the WIYN Open Cluster Study (WOCS), they have obtained 1300 high-resolution spectra of over 340 stars (V < 17) in NGC 188. Median measurement precisions are 0.4 km/sec. Over 50 velocity variables have already been identified, with orbital solutions having been obtained for 5. First-epoch observations have been obtained for more than 200 stars in the rich Pleiades-age open cluster M35 and for more than 125 stars in the very young cluster NGC 2264. They began a thesis study of the l Orionis OB association in order to study the history of star formation and the initial mass function throughout the region. The initial project is an analysis of the spectral energy distributions of Ha and IRAS selected sources in the vicinity of the B30 cloud.
Verbunt (Amsterdam), van den Berg (Amsterdam) and Mathieu are studying three stars which lie 0.7 mag below the subgiant branch in the M67 color-magnitude diagram. Proper motions and radial velocities confirm their membership, and radial velocities have shown that two of the three stars are spectroscopic binaries. One has a circular orbit with a period of 2.8 days. The more luminous component is rotating rapidly with vsin i Å 50 km/sec, suggesting that this system has gone through a recent mass transfer episode. The second binary, a strong X-ray source, shows an inverse P-Cygni Ha profile. These stars may represent a new evolutionary state of close binaries.
von Hippel, with Gilmore (IoA, Cambridge) and D.H.P. Jones (RGO), used HST to find white dwarfs in open clusters in order to intercompare white dwarf cooling ages with main sequence stellar evolutionary ages. This work is meant to calibrate stellar evolutionary ages and put the age of the Galactic disk and halo on the same scale. von Hippel is continuing his work with A. Sarajedini (NOAO) to obtain photometry for selected open clusters using the KPNO Schmidt, the CTIO Schmidt, and the KPNO 0.9m telescopes in support of the WIYN Open Cluster Study. They are laying the photometric basis for a detailed kinematic, astrometric, photometric, and abundance survey of a dozen open clusters which will take place at WIYN over the next ten years. In addition, von Hippel and Sarajedini are currently using WIYN observations to search for white dwarfs and to calibrate stellar evolutionary ages in NGC 188, one of the oldest known open clusters. The WIYN data for NGC 188 are currently being analyzed.
Whitford has been investigating the structure of the inner disk of the Galaxy as shown by the distribution of OH/IR stars found in the Leiden-based survey of the equatorial belt (|b| < 3o) using the Australia Telescope Compact Array. His tentative conclusions are: (1) The disk interpenetrates the bulge with an exponential density gradient consistent with that found outside of the bulge. (2) There is no hole in the disk inside R Å 3 kpc, where there is a dearth of H II regions. (3) OH/IR stars at 1o < |b| < 3o follow the general density gradient; for |b| < 0.5o, R > 3 kpc there is an excess through the molecular ring where there is currently a high rate of star formation. (4) Scale heights are consistent with these stars being relatively young objects.
Acord, Walmsley (Arcetri), and Churchwell published an extensive analysis of several molecular line profiles towards G5.89, one of the most massive and energetic outflows yet detected. Shepherd, Churchwell, and Willner (1997) completed a high resolution study of the ON2-N massive star formation region. At high spatial resolution, this region has at least 3 outflows indicating several massive stars in the process of accreting mass and ejecting matter. Churchwell (1997) pointed out several implications of the large masses found in massive star outflows fed by infalling matter that did not accrete onto the central star.
Afflerbach, Churchwell, and Werner (JPL) published the results of their abundance determinations of O/H, N/H, and S/H as a function of radial position in the galaxy, using data obtained with the KAO. They found that all three elements decrease linearly with galactocentric radius with about the same gradient. There seems to be no evidence for secondary production of N.
Faison, Churchwell, and Hofner have collaborated with Hackwell, Lynch, and Russell (Aerospace Corp.) on an analysis of the 3-14 µm spectra of 26 UltraCompact HII regions obtained at the NOAO 1.3m telescope using the Aerospace BASS spectrograph. Hydrocarbon emissions at 3.3, 8.7, and 11.3 µm, [Ne II] 12.7 µm, and the 9.7 µm silicate feature were observed in many nebulae. Possible correlations between these features are discussed and radiative transfer models were calculated for 10 of the nebulae. These results have been submitted to the ApJ.
Hofner and Churchwell (1997) found hard X-ray emission from the W3 core. The Fe XXV line at 6.7 kev is also present, but with a luminosity too small to account for the extended galactic disk emission detected by Yamauchi and Koyama (ApJ, 1993). There does not appear to be an adequate explanation for the extended hard X-ray emission of W3.
Faison is using the VLA and VLBA to map HI in absorption in front of 3C138 and other bright extragalactic compact radio sources. Significant optical depths are found in 20 milliarcsec structures, corresponding to _10 AU, with implied densities up to 106 cm-3. Faison expects to be at NRAO until his thesis is completed.
Gibson and Nordsieck completed a multiwavelength investigation of reflection nebulosity around the Pleiades cluster. Scattered-light photometry obtained in the vacuum UV with the Wide-field Imaging Survey Polarimeter (WISP) rocket flight and in the visible with a Burrell Schmidt deep Bj-band mosaic agree with previous measurements taken near 23 Tauri. The larger nebula is fainter than expected in the UV, with a much flatter spectrum than the illuminating stars. A forward-scattering geometry is implied by the greater concentration of visible and UV light than thermal radiation observed in IRAS and DIRBE surveys. A similar relation between the UV and visible components indicates the dust grains are more forward-throwing at 2200 than 4400 Å. The flatness of the nebular spectrum is best explained by reddening of starlight incident on the grains, despite the nebula's optical thinness along most observed sightlines.
Gibson and Nordsieck, with M.A. Holdaway (NRAO), also tested the interposed-sheet scattering model for the Pleiades by studying the HI 21cm line emission and Na I D-line interstellar absorption associated with the nebula. A VLA mosaic combined with short spacing data from the Green Bank 140-foot telescope shows excellent agreement between dust filaments and HI structure over a limited velocity range at angular scales as small as 1'. KPNO Coude Feed echelle observations show Na I absorption features in this same range toward cluster stars but absent in nearer sightlines. The identity of gas and dust filaments with a radial velocity 10 km/s greater than the cluster's conclusively demonstrates the nebula is the result of an interstellar collision. Kinematic analyses of the Green Bank data are in progress to examine this interaction in detail. The fine-scale HI structure is the smallest yet observed in 21-cm (0.04 pc), and may have bearing on the unexpectedly low UV flux (see above) if dust is clumpy. An extension to the VLA mosaic shows the narrow HI filaments are characteristic of the entire nebula, and most likely of the diffuse ISM in general.
Lu (CIT), Savage, Sembach (JHU), Wakker, Sargent (CIT), and Oosterloo (CSIO) have determined the metallicity and dust content of the high velocity cloud at 240 km/sec in the direction of NGC 3783 ( l = 287o, b = 23o). The measurements are based on HST observations of S II and Fe II absorption and H I 21 cm interferometric observations obtained with the Australia Telescope. They find S/H = 0.25 ± 0.07 solar, Fe/H = 0.033 ± 0.006 solar , and S/Fe = 7.6 ± 2.2 solar. The S/H value provides an accurate measure of the metallicity of the cloud while the value of Fe/H clearly indicates the presence of dust in the cloud. The observed metallicity and depletion of Fe obtained combined with the velocity and position of the cloud on the sky strongly suggest this High Velocity Cloud has originated from the Magellanic Clouds.
Maciejewski, D. Cox (Physics), and Shelton (GSFC) are investigating the structure of the W44 supernova remnant, which appears to evolve in a density gradient in a dense medium. They were able to find a simple analytical estimations of its size, expansion velocity and the cooling time. Detailed analysis was done with the help of hydrocodes. The important conclusions are: 1) if thermal conduction in the remnant interior is taken into account, the density and temperature distribution agree well with observations, with no need to add evaporating clouds, wind driven shells etc.; 2) the 21cm emission comes from a partially formed shell in a density gradient; 3) similarly, the density gradient is responsible for the appearance of the radio continuum emission, generated mostly by compression of the ambient cosmic rays and magnetic field.
Mathis, with Torres-Peimbert and Peimbert (UNAM), investigated the possible causes of the observational discrepancy within planetary nebulae between the O+2/H+ abundance ratios as derived from collisionally excited lines and from recombination lines. A similar discrepancy exists for C+2/H+. They predicted the effects of strong fluctuations in both temperature and density. Mathis also published models of composite interstellar grains that use a minimum of heavy elements as is indicated by recent observations. A following paper shows that these models explain the strengths of the interstellar silicate features as well.
Otte and Gallagher, with Scowen and Hester (ASU), studied the motion of the wisps in the Crab Nebula on WFPC2 images. They calculated the relativistic velocities of the wisps and fitted models to the observed data.
Reynolds, Tufte, Haffner, Quigley, and Hausen have used the Wisconsin Ha Mapper (WHAM), a Fabry-Perot spectrometer operating on Kitt Peak, to obtain spectra of [O I] 6300 in three directions that sample the warm ionized medium (WIM). Weak interstellar [O I] emission was clearly detected in all three directions. According to photoionization models, the resulting [O I]/Ha intensity ratios suggest that most of the diffuse Ha and [O I] emission originates from density bounded, nearly fully ionized regions. WHAM observations of the M, A, and C High Velocity Cloud complexes have revealed faint Ha emission (EM = 0.1 - 0.4 cm-6 pc) coincident, both spatially and in radial velocity, with the 21 cm emission. WHAM has mapped part of the sky in [S II] 6716 and [N II] 6584 to probe variations in the ionization and excitation conditions within the WIM.
In collaboration with Heiles (Berkeley), Reynolds and colleagues have used part of the WHAM Ha survey to investigate the structure and kinematics of the Orion - Eridanus Superbubble region.
Sembach (JHU), Savage, Lu (CIT) and Murphy (JHU) are studying highly ionized gas detected in Galactic high velocity clouds toward bright extragalactic sources. High velocity C IV absorption has been seen along 3 of the 10 extragalactic sight lines sampled at 15 km /sec resolution with the GHRS not including the directions to the LMC and SMC. The sky covering factor of highly ionized HVCs appears to be roughly similar to that for H I-High Velocity Clouds (HVCs.) The ionization conditions in the C IV-HVCs more closely resembles that found in QSO absorption line systems than in typical diffuse clouds of the Milky Way disk and halo.
Wakker and van Woerden (Rijks Universiteit Groningen) studied distances to HVCs. They placed the large HVC complex H, (l = 131o, b = 0o, v(lsr) = -200 km/s) at > 5 kpc. Preliminary results regarding HVC complex C give d > 5 kpc, or z > 3 kpc. HST Goddard High Resolution Spectrograph MgII spectra for two stars (PG0859+593, PG0906+596) and an extra-galactic object (Mrk 106) were combined with HI data to show that MgII is present in HVC complex A, while the non-detections toward the stars give a lower limit to the distance of complex A of 4 kpc, or z > 2.5 kpc. The H and K absorption in the spectrum of the RR Lyrae star AD UMa (d = 10 kpc) seen projected towards complex A provides the first distance bracket for a HVC, showing that it is in the galactic halo. Wakker and colleagues obtained observations of the 115 GHz CO J = 1-0 line in the direction of HVC cores were published. No CO was detected at HVC velocities, down to a 5-sigma limit of 0.077 K km/s, or N(H2) < 9 1018 cm-2 with the median I(CO)/N(H2) conversion factor appropriate for high-latitude translucent clouds. The limits on volume densities from the non-detections then indicate that the observed HVCs are more distant than 2 kpc.
Bershady has continued working with students Jangren and Andersen (see the listing for Penn State University.) His recent work has focused on constraining the z > 3 field galaxy luminosity function and on understanding how to select such high redshift galaxies on the basis of color and image structure. This work has been in collaboration with S. Majewski, J. Charlton, D. Weedman, and D. Schneider, as well as two undergraduates J. Geoffroy and J. Wolovitz.
Cole and Gallagher continued their participation in a major HST imaging program to characterize the properties of aging stellar populations in the far-UV regime. Cole and Gallagher's work focused on resolved stars in Magellanic Cloud star clusters and Local Group dwarf galaxies. They published the first results of an HST imaging program designed to use the rich, intermediate- and old-age star clusters in the LMC as laboratories for studying the astrophysical origins of the elliptical galaxy "ultraviolet excess" phenomenon. Gallagher, Han (now at GSFC), and Wyse (JHU) are investigating the structures of dwarf galaxies in clusters, where strong perturbations might be present.
Cole, Nordsieck, and Wood (CfA) began to model the distribution and optical properties of dust grains in the diffuse ISM of the LMC. The modeling effort uses a 3-dimensional Monte Carlo code to match the known spatial and luminosity distribution of OB associations to the ultraviolet imaging polarimetry data obtained by Nordsieck et al. with the WISP rocket payload.
Conselice has studied the classification of galaxies using symmetry about the center as the fundamental parameter. Conselice and Gallagher are considering small scale substructure in galaxies (in particular some aggregate structures in the Coma Cluster) and have been investigating the core of NGC 6166 for structural irregularities. With Evans (Yerkes Obs.) and White and Keel (U. Alabama), Conselice continued to study extragalactic dust by examining images of overlapping galaxies.
Erwin, Sparke, and Gallagher are using WIYN to survey 39 nearby (v _ 2000 km s-1) early-type nearly face-on barred spirals outside of the Virgo Cluster to search for double-bars and other nuclear features. They focused on multiply barred galaxies in order to build up statistics on the frequency of these systems. Of 28 galaxies observed so far, 5 clearly have secondary bars and an additional 3 are candidates.
Gallagher continues to act as a PhD thesis advisor for L. Mathews (SUNY Stony Brook) in her studies of extreme late-type spirals. Results from an optical CCD study at CTIO are in press, and single-dish HI 21-cm profiles obtained in collaboration with van Driel (Obs. Paris) are nearing completion. The analysis of optical rotation curves from CTIO long-slit spectra is in progress.
Gallagher and Hoessel are collaborators in HST WFPC2 imaging projects by Skillman (U. Minnesota) to observe color-magnitude diagrams in nearby dwarf irregular galaxies. The diffuse ionized gas in Sextans A and Pegasus indicates complex star formation histories. Cole and Tolstoy (Space Telescope -European Coordinating Facility), also collaborators, are obtaining additional population studies using the WIYN telescope and facilities at the European Southern Observatory.
Gallagher continues his investigations of luminous, compact "super star clusters" in nearby galaxies. He and Watson (UNAM) are leading an HST WFPC2 study of super star clusters in active regions around the nucleus of the SBc galaxy NGC 2903. L. Smith (Univ. College London) and Gallagher obtained optical spectra of M82 cluster F at 1 Å resolution showing spectral signatures of B6 stars in the blue and Ca II triplet absorptions from cool stars in the red. O'Connell (U. Virginia) and Gallagher have obtained HST NICMOS observations of M82 to survey properties of star clusters.
Hensler (Kiel) and Gallagher are combining theoretical and observational perspectives in chemo-dynamical models of galactic evolution. They include the effects of gravity, a multiphase ISM, and the energy inputs from stars as they synthesize heavy elements. Ongoing projects include analysis of ROSAT X-ray observations of starburst galaxies and the evolution of dwarf elliptical galaxies.
Gallagher and Homeier investigated he star formation properties and history of NGC 7673, a clumpy, blue irregular at Å 3400 m/s that appears to be undergoing an interaction or merger. They are using HST WFPC2 photometry in V and I, as well as R and H from WIYN.
Howk and Savage have exploited the superb image quality provided by WIYN to probe the disk-halo interface region of edge-on spiral galaxies. The first images for the edge-on spiral NGC 891 (see AJ, December 1997) show an extremely complex network of dusty filaments stretching to heights above the midplane of more than 1.5 kpc. The high-z dust structures seen in this galaxy may contain a significant amount of gas (>105 solar masses) and require a large amount of energy (>1052 ergs) to attain their observed heights above the midplane of the galaxy, assuming Milky Way gas and dust relationships.
Maciejewski and Sparke are investigating gas inflow to the centers of galaxies having small central bars within larger kiloparsec-scale bars. Significant gas inflow can occur in barred galaxies; strong shocks form along the bar axis, extracting angular momentum from the passing gas. These shocks do not extend to the galaxy center, and in models, inflowing gas accumulates as an inner ring. If a second, smaller, bar forms close to the galactic center, it will probably be rotating faster than the large bar, so that the gravitational potential is not constant in any rotating frame. It has previously been thought that orbits in such a time-varying potential were likely to be highly chaotic, but by extending the concept of a periodic orbit, Maciejewski & Sparke (1997) were able to find orbits supporting each bar separately. They also investigated gas flow in a double-bar system, using a simple approach based on damped epicyclic equations of motion. These equations predict periodic feeding of gas into the nucleus, and gas flow lines form a stable multiply-periodic flow pattern. The next step is hydrodynamical modeling in order to estimate the rate at which gas flows into the galaxy center.
Savage, Tripp (Princeton), and Lu (CIT) have studied the associated and intervening O VI absorption line systems in the UV spectrum of the bright QSO H 1821+643 (m(V) = 14.2, z(em) = 0.297). Ground based galaxy redshift measurements reveal two emission line galaxies near the redshift of the intervening system at z(abs) = 0.225, suggesting the existence of a galaxy group at this redshift. If the gas has a metallicity of ~0.1 solar, the ionization characteristics of the intervening system can be explained by an extended (~180 kpc) diffuse gas distribution that is photoionized by the meta-galactic UV background. This gas may be associated with the extended halo of the luminous intervening spiral galaxy at a projected distance of 100 kpc, or with an intra-group medium. Alternatively the absorption may be produced in hot collisionally ionized halo gas or in the intra-group medium. The associated system with z(abs) = 0.297 contains narrow and broad O VI absorption. The narrow absorption which is also detected in H I, C III, C IV, and Si IV can be modeled as gas photoionized by H 1821+643 with ~solar abundances. This gas is probably situated close to H 1821+643. The broad O VI absorption which is centered at the emission redshift of H 1821+643 may represent a weak and narrow example of the broad absorption line phenomena. Another possibility is the broad O VI absorption occurs in 105 -106 K gas associated with a cooling flow in the rich X-ray luminous cluster surrounding H 1821+643 or with a cooling flow in the host elliptical galaxy H 1821+643 resides in. However, the observed O VI column density is 60-120 times smaller than expected for gas in a simple cooling flow passing through the 106 to 105 K temperature regime. The strong radiative flux from H 1821+643 could substantially modify the ionization of the cooling gas in the flow and may help explain the discrepancy.
Savage is a member of the HST QSO Absorption Line key project team. The team released the third in a series of Catalogs of QSO absorption lines. The third catalog includes 2594 absorption lines seen in the UV spectra of 66 QSOs. Combining the results from the three catalogs brings the total number of detected absorption lines to 3283 including: 1089 Ly-a lines, 20 extensive metal line systems, 103 C IV systems, and 42 O VI systems. These data are being used for a wide variety of investigations of gaseous systems in the nearby universe including studies of the redshift evolution of the Ly-a forest and metal line systems and studies of the association of QSO absorbers and galaxies. Savage and Lu (CIT) are using the combined results from all three Key Project catalogs to study the Milky Way absorption by Mg II and Fe II toward the QSOs in order to determine the sky covering factor of Galactic high velocity Mg II and Fe II absorption. The metal line high velocity cloud covering factor will be compared to the covering factor found from H I 21 cm emission line studies. The Milky Way lines will provide important examples of the range of absorption properties of a zero redshift (current epoch) galaxy for comparison with absorption seen at higher redshift in QSO metal line systems.
Sparke, while on sabbatical leave at the Kapteyn Lab (Groningen) and Mt. Stromlo Obs. (Australian National University), observed southern polar ring galaxies in H I with the Australia Telescope Compact Array and investigated ionized gas in the rings with optical spectroscopy.
Tripp (Princeton), Lu (CIT) and Savage have obtained a high S/N GHRS spectrum of the bright quasar PG 1116+215 (z = 0.177) over the range 1225 — 1500 Å in order to study the relationship between galaxies and low column density low redshift Ly-a clouds. The GHRS results for PG 1116+215 will be combined with those previously obtained for H 1821+643 and 3C 273 to nearly triple the size of the sample of low redshift Ly-a lines seen down to four-s detection limits of ~ 50 mÅ. Galaxy redshifts in 1o diameter fields centered on PG 1116+215 and H 1821+643 have been obtained with the WIYN Multi-Object Spectrograph. A statistical analysis of the relationship between galaxies and Ly-a lines is underway.
von Hippel, H. Ferguson (Space Telescope Science Institute), and N. Tanvir (IoA, Cambridge) are using HST photometry to detect intergalactic stars in the Virgo Cluster of galaxies. Intergalactic stars are expected from the cluster formation process, which should have involved numerous galaxy collisions and disruptions. Prior to their work, no direct evidence for intergalactic stars existed. One paper has been completed on this work and further HST time has been allocated. von Hippel, along with several Wisconsin, NOAO, and international collaborators, began using the Kitt Peak 0.9m and WIYN telescopes to search for and monitor gamma ray bursters.
Wakker and colleagues found the first unambiguous evidence that C+3 exists in the LMC away from regions where it could have been produced locally. Kinematic differences between low- and high-ionization lines indicate that at least some of the C+3 is in a corona, but the distribution is not uniform. The average properties of the LMC C IV lines are similar but not identical to those found for the Milky Way. The similarity of parameters of the high-ionization lines to those found in the Milky Way gas suggests that similar processes are responsible for the production of C IV.
Pisano, Wilcots, and Elmegreen (IBM) completed a study of the distribution and kinematics of H I in two late-type barred spiral galaxies, NGC 925 and NGC 1744. Corotation in NGC 925 occurs at the edge of the optical disk, indicating that either the bar rotates extremely slowly or that the bar and spiral rotate with different speeds. NGC 925 is also interacting with a small H I cloud. WIYN data show that the cloud contains no stellar component. The streaming motions associated with the bar and spiral arms in both galaxies are quite weak. Pisano and Wilcots are also using WIYN observations to measure the star formation rate and history in NGC 925 and NGC 1744 as part of a larger study of the characteristics of late-type barred spiral galaxies.
Wilcots and Miller (DTM) completed the first stage in a comprehensive study of the Local Group dwarf irregular, IC 10. High resolution VLA H I maps and WIYN Ha images reveal a complex ISM. Vigorous star formation is currently taking place along a network of H I filaments. The lack of expanding H I shells indicates that either the H I holes are very old or are caused by something other than stellar winds and supernovae. A VLA H I mosaic shows the main disk of IC 10 is embedded within a large collection of neutral gas and that IC 10 appears to be accreting a small H I cloud. Wilcots is continuing a similar study of the relationship between massive star formation and the dynamic ISM in IC 1613, another dwarf irregular in the Local Group.
Wilcots, Hunter (Lowell), van Woerden (Kapteyn), Gallagher, and Kohle (Bonn) reported on their discovery of a spectacularly complex distribution of gas surrounding NGC 4449, a nearby Magellanic irregular. They find that NGC 4449 either continues to accrete its original gaseous halo or has suffered through a recent gravitational interaction. They are combining a VLA H I mosaic with Dominion Radio Astronomy Observatory data. Wilcots and Turnbull have detected small H I clouds around two Seyferts, Mrk 3 and NGC 6764. Wilcots and Molvig are mapping the distribution and kinematics of H I associated with the late-type barred spirals NGC 672 and IC 1727.
Wilcots and Baker are using WIYN to investigate the morphology and star formation history of barred Magellanic spirals. In a related study, Wilcots is using the VLA and WIYN to investigate the effects of gravitational interactions on the asymmetries of Magellanic spirals.
Wilcots and Galarza (NMSU) are investigating the physical properties of small H II regions in the LMC in order to correlate the ionization structure and morphology of individual regions with the spectral type and luminosity class of the ionizing star(s). The combination of emission line imaging and radio continuum maps is providing detailed two dimensional maps of the distribution of reddening across each region.
The department unveiled a new introductory astronomy curriculum in Fall 1997-98, in which two new lecture courses and threecomputer-based labs were created. In addition to offering a traditional broadsurvey of all of astronomy, the department now offers one introductorycourse emphasizing stars and galaxies and one focusing on our place inthe solar system. Complementing each lecture course is acomputer-based lab in which students gain a deeper appreciation forscience while in a collaborative environment.
Mathieu was a member of the College Level 1 team of the National Institute of Science Education on the Madison campus. The primary activity was development of an annual CL-1 Institute to examine critical issues of first-year courses in science, math, engineering, and technology. The essential goal of these Institutes will be to synthesize present knowledge and disseminate it to practitioners. The first Institute will begin in Fall 1998 and focus on assessment.
Stassun, Dolan, Gnam, Pisano, and Hoffman conducted an adult lecture series on astronomy at UW Space Place. Stassun, Dolan, Pisano, and Hoffman also developed and taught a two-week astronomy course for the Academic Skills Development Workshop, a college-access program for high-school students. Hoffman led workshops for "Explorathon" and "Expanding Your Horizons," statewide programs for encouraging middle-school and high-school-aged girls in math and science.
For the second consecutive year Wilcots coordinated the "Universe in the Park" program. Throughout the summer, faculty, research scientists, and graduate students went to state parks throughout Wisconsin to give a short presentation on the latest astronomical news and to host star parties for park visitors. "Universe in the Park" sessions were held in twenty different state parks.
The WIYN Observatory consortium is composed of the University of Wisconsin, Indiana University, Yale University and the National Optical Astronomy Observatory (NOAO). The WIYN 3.5m telescope is located on the western ridge at the Kitt Peak National Observatory. The University of Wisconsin has a 26% share in the observing time. WIYN continues to produce optical images of excellent quality, with a median RMS FWHM for the R band of 0.8". The "general use" instruments for WIYN include the multi-object spectrograph (MOS/Hydra) and an imaging camera system. Both instruments are fully operational and producing excellent data. MOS/HYDRA with its fiber positioner and bench mounted spectrograph allows the simultaneous acquisition of 100 optical spectra with low to moderate spectral resolution over the full one degree field of WIYN. The imaging camera contains a 2048x2048 CCD providing a field of 6.7'x 6.7' and 0.2"/pixel sampling.
This year saw the commissioning of DensePak, a fiber optic bundle used for integral field spectroscopy. The bundle forms an array of 91 fibers arranged in a seven fiber by thirteen fiber rectangle. DensePak attaches to the telescope at the imaging port using the Indiana WIFOE head adapter and feeds the bench spectrograph. The commissioning effort was led by Sawyer (Site Manager). The wavefront pipeline was completed (allowing the mirror figure to be tested in under 6 minutes) and the atmospheric dispersion corrector at the imaging port was installed and underwent verification tests. The Wisconsin HPOL spectropolarimeter (Nordsieck, PI) was mounted on the WIYN telescope for the winter months.
The WIYN consortium initiated a 2-year program to complete residual commissioning tasks and upgrade the telescope. Most of the items addressed in the first year were related to safety. Members of the consortium also met in Baltimore and in Madison for major strategic planning sessions, the results of which are in preparation. Code (Observatory Scientist) organized a consortium-wide exploration of adaptive optics options for WIYN. Jacoby (Telescope Scientist) led an effort which characterized WIYN seeing performance. The consortium initiated development of a tip-tilt system correcting up to a 5' field of view.
Percival continued his work on Progressive Image Transmission, with which very large images can be sent over very slow network connections. This work is the central feature of the WIYN Remote Observing System, allowing WIYN images to be received and examined in less than 1% of the expected transmission time. Percival also continued his work on the WIYN Remote Engineering Data System, which allows remote users to monitor every aspect (tracking, servos, voltages, temperatures) of an observing session.
von Hippel has worked with a team led by George Jacoby (NOAO) to test the potential for adaptive optics at WIYN. von Hippel has also supported a number of Wisconsin programs at WIYN, both as a queue observer and providing local support for Wisconsin's remote programs.
The staff has been involved in many instrumental projects, listed below in alphabetical order.
Cosmic Origins Spectrograph (COS), selected by NASA to be the HST replacement instrument for the 2002 HST orbital refurbishment mission. Savage is a Co-Investigator on the COS science team with J. Green ( U. Colorado) serving as the Principal Investigator. COS will be built at the U. of Colorado and Ball Aerospace in Boulder. COS is a very high through-put spectrograph operating from 1150 to 1800 Å at a resolution of 22,000. The COS science team is evaluating the possibility of extending the wavelength coverage of the spectrograph to 3000 Å. COS is approximately 20 times more efficient than the Space Telescope Imaging Spectrograph and will be used for a wide range of spectroscopic studies of faint galactic and extragalactic objects. Savage's observational studies with COS will involve the origin of hot gas associated with galaxy halos. These studies will be pursued through absorption line observations of highly ionized ions in the UV spectra of QSOs.
Far-Ultraviolet Spectrographic Explorer (FUSE). Savage is a Co-Investigator for the FUSE satellite which is being prepared for launch in the fall of 1998. FUSE is a dedicated UV spectroscopy mission operating at 912 — 1200 Å at a spectral resolution of 30,000. Savage's observational program with FUSE involves measurements of O VI absorption produced by the hot interstellar medium of the Milky Way disk and halo. The goal will be to study the distribution and kinematics O VI in order to gain insights about the origin(s) of the hot gas in the ISM.
Hobby Eberly Spectrograph : Bershady has begun an NSF-funded instrumentation program to build a fiber integral field unit for the Hobby Eberly Telescope's Medium Resolution Spectrograph. This instrument will be used to study the kinematics of galaxy disks.
HPOL (Halfwave Polarimeter): As before, HPOL split time between WIYN and PBO, spending 3 months at Kitt Peak and the rest at Pine Bluff. During its WIYN run HPOL obtained data on 9 nights in both the standard mode and a new faint mode configuration. In all, HPOL obtained 210 observations of 89 distinct targets over the course of 95 nights between Oct. 1 1996 and Sept. 24 1997. Although HPOL observes a wide range of objects, two specific campaigns were attempted. Sixteen faint mode observations of Comet Hale-Bopp were made in early 1997, while 15 observations of the interacting binary Beta Lyr were made during the months of July and August 1997. Broadband polarimetric results of HPOL observations continue to be listed on the HPOL website (http://www.sal.wisc.edu/HPOL)
IR Fabry-Perot: Reynolds, Bennett (PI) and Kutyrev (Goddard Space Flight Center), and Roesler (UW Physics) have developed a high-throughput infrared Fabry-Perot spectrometer for high spectral resolution studies of the 2 µm Br-g line from optically obscured diffuse H II regions. Kutyrev performed a preliminary survey of interstellar Br-g from Mauna Kea.
SHS (The Spatial Heterodyne Spectrometer) (Roesler, Sanders (Physics), Harlander (St. Cloud State), and Reynolds): the SHS interferometer has been completed and the sounding rocket payload is presently being assembled for a flight in April 1998. SHS is a new type of extremely high throughput Fourier transform spectrometer for investigations of faint ultraviolet line emission from the "coronal" (105 K) component of the ISM. It is a NASA supported collaboration between the Department of Physics (F. Roesler, PI, and W. Sanders), the Space Astronomy Laboratory (Reynolds), and St. Cloud State University, MN (J. Harlander).
WFPC2 (Wide-Field and Planetary Camera 2) on the HST: Gallagher and Hoessel continue as members of the Investigation Definition Team led by J. Trauger (JPL). The team expects to finish its Guaranteed Time Observing program in 1998.
WHAM (The Wisconsin H-Alpha Mapper) (Reynolds, Tufte, Haffner, Quigley, Hausen): WHAM was installed at Kitt Peak in November, 1996, and the Ha sky survey began in January 1997. Over 25,000 Ha spectra have been obtained with a 1.0o diameter beam on a 0.85 x 0.98 square degree grid covering the Galactic plane between longitudes 10o and 240o and latitudes -50o to +50o. Each spectrum covers a 200 km/s interval about the LSR with a velocity resolution of 12 km/s and an emission measure sensitivity of approximately 0.3 cm-6 pc. The survey observations should be completed by September, 1998.
WIYN Adaptive Optics: Code has led a project to develop an adaptive optics capability. An initial project for a fast tip-tilt camera is in progress. It involves scientists from the WIYN partners, including Gallagher.
WISP (The Wide-field Imaging Survey Polarimeter:; Nordsieck, PI) is a suborbital rocket payload telescope that flew on its third successful mission in April, taking the first-ever polarimetric UV images of a comet (Hale-Bopp). Data are under analysis. The instrument has two broadband filters centered at 1650 and 2200 Å and a field of 5.0 x 1.7o. WISP observations of geometrically simple reflection nebulae constrain both the currently controversial UV scattering properties of interstellar dust and the 3-D geometry of the reflection nebula. Previous missions have observed diffuse galaxian light in the LMC and faint scattered light in the Pleiades reflection nebula. The next WISP target is the M81/M82 mid-latitude cirrus region, targeted for the spring of 1998.
Lawler's group (Physics) measures branching ratios using a Fourier Transform or grating spectrometer, radiative lifetimes using laser-induced fluorescence, and absorption oscillator strengths of astrophysical interest using an absorption experiment based at the Synchrotron Radiation Center. In the past year, lifetime measurements were made on Tm I, Tm II, Re II, C I, Cr I, Dy I, Dy II, Lu II, and Co II. Branching ratios were measured in Co II, Lu II, P II, Re II, Tm I, Tm II, Ni I, and N II. Absolute vacuum ultraviolet oscillator strengths were measured for Fe II and work on the vacuum ultraviolet Co II lines continues.
10.
Refereed publications and Invited Reviews
Acord, J. M., Walmsley, C. M., Churchwell, E. "The Extraordinary Outflow Towards G5.89-0.39", 1997, ApJ, 475, 693
Afflerbach, A., Churchwell, E., Werner, M. W. "Galactic Abundance Gradients from IR Forbidden Lines in Ultra Compact H II Regions" 1997, ApJ, 478, 190
Anderson, C. M., Weitenbeck, AJ, Code, A. D., Nordsieck, K. H., Meade, M. R., Babler, B. L., Zellner, N. E. B., Bjorkman, K. S., Fox, G. K., Johnson, J. J., Sanders, W. T., Lupie, O. L., and Edgar, R. J., "Ultraviolet Interstellar Polarization of Galactic Starlight I. Observations by the Wisconsin Ultraviolet Photo-Polarimeter Experiment" 1996, AJ, 112, 2726
Anderson, H. M., Den Hartog, E. A., and Lawler, J. E. "Radiative Lifetimes in TmI and Tm II" 1996, J. Opt. Soc. Am. B 13, 2382
Bahcall, J. N., Bergeron, J., Boksenberg, A., Hartig, G. F., Jannuzi, B. T., Sofia Kirhakos, Sargent, W.L.W., Savage, B.D., Schneider, D.P., Turnshek, D., Weymann, R.J. and Wolfe, A.M. "The HST Quasar Absorption Line Key Project VII: Absorption Systems at zabs < 1.3" 1996, ApJ, 457, 19
Basri, G., Johns-Krull, C.M., and Mathieu, R.D., "The Classical T Tauri Binary DQ Tau. II. Emission Line Variations with Orbital Phase", 1997, AJ, 114, 781
Berghöfer, T. W., J.H.M.M. Schmitt, and J.P. Cassinelli, "The ROSAT all-sky survey catalogue of optically bright OB-type stars", 1996, A&AS, 118, 481
Borumand, M., Joynt, R., & Kluzniak, W. "Superfluid densities in neutron star matter," 1996, Phys. Rev. C, 54, 2745
Borumand, M., Kluzniak, W., "On the distribution of BATSE gamma-ray bursts," 1996, in Gamma-ray bursts, C. Kouveliotou, M.S. Briggs and G.J. Fishman eds., AIP Conference Proceedings, 384, (AIP: New York), 326
Brandt, J.C. and 20 co-authors ( including Savage, B.D.) " High Signal-to- Noise Ratio Observations of Weak Interstellar Absorption Lines Towards Zeta Ophiuchi with the Goddard High Resolution Spectrograph Aboard the Hubble Space Telescope" 1996, AJ, 112, 1128
Brandt, J.C. and 20 co-authors ( including Savage, B.D.) "Observations of 3C 273 with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. II." 1997, AJ, 114, 554
Burrows, C. J., Stapelfeldt, K. R. , Watson, A. M., Krist, J. E., and WFPC-2 IDT (including Gallagher), 1996, "Hubble Space Telescope Observations of the Disk and Jet of HH 30," ApJ, 473, 437.
Cardelli, J. A., Meyer, D.M., Jura, M., and Savage, B.D. "The Abundance of Interstellar Carbon", 1996, ApJ, 467, 334
Cassinelli, J. P. "EUV Radiation from B-stars: the Broad Implications for Stellar and Interstellar Astronomy", 1996, Invited review in IAU Colloquium 152, "Astrophysics in the Extreme Ultraviolet," ed. S. Bowyer and R.F. Malina (Kluwer: Dordrecht), 367
Cassinelli, J. P. and H.J.G.L.M. Lamers, "Mass Loss from Stars", 1996, invited review in "The Impact of Stellar Physics on Galactic Evolution, ed C. Leitherer, U. Fritze-v. Alvensleben, and J. Huchra (ASP:San Francisco), 162
Cassinelli, J. P., F. Najarro, R. Kudritzki, O. Stahl, & D. J. Hillier. "Stellar Winds and the EUV Continuum Excess of Early B-Giants", 1996, A&A, 306, 892
Cassinelli, J.P., D. H. Cohen, J. J. MacFarlane, J.E. Drew, A. E. Lynas Gray, I. Hubeny, J. V. Vallerga, B. Y. Welsh, and M. G. Hoare, "EUVE Spectroscopy of beta Canis Majoris (B1 II-III) from 500 to 700 Angstroms", 1996, ApJ, 460, 949
Cassinelli, J. P., Berghöfer, T. W., & Schmitt, J.H.M.M., "X-ray properties of OB stars derived from The ROSAT all-sky survey", 1996, A&A, 322, 167
Churchwell, E. "Origin of the Mass in Massive Star Outflows", 1997, ApJL, 479, L59
Churchwell, E. 1997, "Massive Star Formation: Observational Constraints", invited review in Herbig-Haro Flows and the Birth of Low Mass Stars, eds B. Reipurth and C. Bertout, Kluwer Acad. Pub., 525
Clarke, J.T., Ballester, G.E., Trauger, J., Evans, R., Connerney, J.E.P., and WFPC2 IDT (including Gallagher) 1996, "Far Ultraviolet Imaging of Jupiter's Aurora and the Io 'Footprint'," Science, 274, 404.
Clayton, G.C., Bjorkman, K.S., Nordsieck, K.H., Zellner, N.E.B., Schulte-Ladbeck, R.E., "Evidence for a Bipolar Geometry in R Coronae Borealis?", 1997, ApJ, 476, 870
Clayton, G.C., Wolff, M.J., Allen, R.G., Babler, B.L., Meade, M.R., Nordsieck, K.H., Anderson, C.M., Martin, P.G., and Whittet, D.C.B., "Ultraviolet Interstellar Linear Polarization. IV. Cross-Calibration Between the Wisconsin Ultraviolet Photo-Polarimeter Experiment and the Faint Object Spectrograph", 1997, AJ, 114, 1132
Coakley, M.M., F. L. Roesler, R.J. Reynolds, and S. Nossal 1996, "Fabry-Perot Annular Summing Spectroscopy: Study and Implications for Aeronomy Applications", Applied Optics, 35, 6479
Cohen, D. H., Cooper, R. G., MacFarlane, J.J., Owocki, S. P., Cassinelli, J.P., and Wang, P. "Evidence for a Multi-Temperature Plasma and Wind Attenuation in the Combined EUVE and ROSAT Observations of e Canis Majoris (B2 II)," ApJ, 460, 506
Cole, A.A., Gallagher, J.S., Freedman, W.L., & Phelps, R.L., "Ultraviolet Color-Magnitude Diagram Studies of Intermediate-Age Large Magellanic Cloud Star Clusters. I. NGC 1783", 1997, AJ, 113, 1700
Cooper, J. C., Gibson, N. D., and Lawler, J. E. "Radiative lifetimes in CrI by Laser-Induced Fluorescence" 1997, J. Quant. Spectrosc. Radiat. Transfer, 58, 85
Cox, A. L. and L.S. Sparke, "Using H I in Polar Rings to Probe Galaxy Potentials", 1996, Minnesota Lectures on Extragalactic Neutral Hydrogen (ASP Conference Series, 106), ed. E. Skillman, 168
Crenshaw, D. M., and others including L.S. Sparke, "Multi-Wavelength Observations of Short-Timescale Variability in NGC 4151 I. Ultraviolet Observations", 1996, ApJ, 470, 322
Curry, J. J., Gibson, N. D., and Lawler, J. E. "Branching ratio measurement of N+ inter-system lines, 2s2p3 5S2 - 2s22p2 3P2,1" 1997, A&A, 321, 1021
Fabbiano, G. , Gallagher, J. S., and A. Renzini, Eds. Windows on Galaxies (Kluwer: Dordrecht) 383P., 1990.
Ferguson, A. M. N., Wyse, R. F. G., Gallagher, J.S., "The Spectacular Ionized Interstellar Medium of NGC 55" AJ, 112, 2567.
Fox, G.K., Code, A.D., Anderson, C.M., Babler, B.L., Bjorkman, K.S., Edgar, R.J., Johnson, J.J., Lupie, O.L., Meade, M.R., Sanders, W.T., Weitenbeck, A.J., Zellner, N.E.B., "Solar System Observations by the Wisconsin Ultraviolet Photo Polarimeter Experiment. I. The First Ultraviolet Linear Spectropolarimetry of Mars", 1997, AJ, 113, 1152
Fox, G.K., Code, A.D., Anderson, C.M., Babler, B.L., Bjorkman, K.S., Edgar, R.J., Johnson, J.J., Lupie, O.L., Meade, M.R., Sanders, W.T., Weitenbeck, A.J., Zellner, N.E.B., "Solar System Observations by the Wisconsin Ultraviolet Photo Polarimeter Experiment. II. The First Linear Ultraviolet Spectropolarimetry of Io", 1997, AJ, 113, 1158
Fox, G.K., "Spectropolarimetry of Mars: The Development of Two Polarization Reversals", 1997, MNRAS, 286, 963
Gallagher, J.S. 1996, "Star Formation Histories of Dwarf Galaxies," in From Stars to Galaxies: The Impact of Stellar Physics on Galaxy Evolution, ASP Conference 98, 315
Gallagher, J.S., Han, M., Wyse, R.F.G., 1997, "Structure of Dwarf Elliptical Galaxies in Dense Clusters," in Dark and Visible Matter in Galaxies, ASP Conference 117, eds. M. Persic & P. Salucci.. 66
Galletta, G., Sage, L., and L.S. Sparke, "Molecular Gas in Polar Ring Galaxies", 1997, MNRAS, 284, 773
Han, M., Hoessel, H.G., Gallagher, J.S., Holtzman, J., Statson, P.B., and WFPC2 IDT 1997, "Stellar Populations in the Dwarf Elliptical Galaxy NGC 147," AJ, 113, 1011.
Harris, W., Combi, M. R., Mueller, B. E. A., Honeycutt, R. K., and Scherb, F., "Evidence of Interacting Gas Flows and an Extended Volatile Source Distribution in the Coma of Comet/C1996 B2 (Hyakytake)", 1977, Science, 277, 609
Hensler, G., Dickow, R., Junkes, N., Gallagher, J. S., 1996, "Soft X-Rays from the Low-Mass Starburst Galaxy NGC 1705," Röntgenstrahlung from the Universe, eds. H.U. Zimmerman, J. Trümper, H. Yorke, MPE Report, 263, p.379.
Hill, R.J., Dolan, J.F., Bless, R.C., Boyd, P.T., Percival, J.W., Taylor, M.J., & Van Citters, G.W. "The Spectrum of the Large Magellanic Cloud Pulsar B0540-69", 1997, ApJ, 486, 99
Hofner, P., Churchwell, E. "Hard X-Ray Emission from the W3 Core", 1997, ApJ, 486, L39
Holtzman, J.A., Mould, J.R., Gallagher, J.S., Watson, A.M., Gillmar, C.J. and WFPC2 IDT 1997, "Stellar Populations in the Large Magellanic Cloud: Evidence for a Significant Number of Older Stars," AJ, 113, 656.
Hunter, D., van Woerden, H., Gallagher, J. S. 1996, "Neutral Hydrogen Observations of the Amorphous Galaxy NGC 4670 at Moderate Spatial Resolution," ApJ Sup., 107, 739.
Hunter, Deidre A, Gallagher, J. S., 1997, "An Emission-Line Study of Supergiant Ionized Filaments in Irregular Galaxies" ApJ, 475, 65.
Ignace, R., Cassinelli, J. & Bjorkman, J.E, "Equatorial Wind-Compression Effects Across the H-R Diagram" 1996, ApJ, 459, 671
Jannuzi, B.T and 11 co-authors (including Savage, B.D.) "The Hubble Space Telescope Quasar Absorption Line Key Project: The Unusual Absorption Line System in the Spectrum of PG 2302+020 --- Ejected or Intervening ?" 1996, ApJ, 470, L11
Jensen, E.L.N. and Mathieu, R.D., "Evidence for Cleared Regions in the Disks Around Pre--Main-Sequence Spectroscopic Binaries", 1997, AJ, 114, 301
Johnson, J.J., Anderson, C.M., Bjorkman, K.S., Code, A.D., Fox, G.K., Weitenbeck, A.J., Sanders, W.T., Babler, B.L., Meade, M.R., Zellner, N.E.B., Edgar, R.J., Magalhaes, A.M., Clayton, G.C., Schulte-Ladbeck, R.E., and Lupie, O.L., "Ultraviolet Spectropolarimetry of Three Classical Novae Early in Outburst: Evidence for Aspherical Shells", 1997, AJ 113, 2200
Kluzniak, W. "Cyclotron Lines and Gamma-Ray Bursts", 1996, Turkish Journal of Physics, 20, 524
Kluzniak, W. "Gamma-Ray Bursts," 1996, Nuclear Physics B (Proc. Suppl.) 48, 400
Kluzniak, W., W.H. Lee, "Gravitational Waveforms for Mergers of Neutron Stars with Black Holes," 1997, in Gravitational Waves Sources and Detectors, I. Ciufolini, F. Fidecaro eds., (World Scientific: Singapore), p. 44
Krist, J.E, & WFPC2 IDT, including Gallagher, J.S., 1997, "Hubble Space Telescope WFPC2 Images of Emission Nebulosity near XZ Tauri," ApJ, 481, 447K.
Lacy, C.H.S., Fekel, F.C., Mathieu, R.D., Morrell, N.I., Morse, J.A., Torres, G. and Willmarth, D., "The Spectroscopic Orbit of p Ceti", 1997, AJ, 113, 1088
Leitherer, C., Alloin, D., Alvensleben, U., Gallagher, J. S., Huchra, J. P., Matteucci, F., O'Connell, R. W., et al, 1996, "A Database for Galaxy Evolution Modeling," PASP, 108, 996.
Maciejewski, W., Murphy, E., Lockman, F.J. and Savage, B.D. "The Aquila Supershell: a Remnant of Multiple Supenovae" 1996, ApJ, 469, 238
Maciejewski, W., Sparke, L. S., "Regular Orbits and Periodic Loops in Multiply- Barred Galactic Potentials", 1997, ApJL, 484, 117
MacFarlane, J.J., D.H. Cohen, and J.P. Cassinelli. "Ionization in the Winds of Early-B stars: Constraints Imposed by EUVE", 1996, in Astrophysics in the Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina, (Kluwer: Dordrecht), 375
Mathieu, R.D., Stassun, K., Basri, G., Jensen, E.L.N., Johns-Krull, C.M., Valenti, J. and Hartmann, L.W., "The Classical T Tauri Spectroscopic Binary DQ Tau. I. Orbital Elements and Light Curves", 1997, AJ, 113, 1841
Mathieu, R.D., "Accretion in Pre-Main-Sequence Binaries", 1997, Proceedings of the 7th Annual Maryland Astrophysics Conference "Star Formation, Near and Far", ed. S. Holt and L. Mundy, 337
Mathis, J. S. "Composition and Size Distribution of Interstellar Dust", 1997, in ASP Conf. Series 122, "From Stardust to Planetesimals", ed. Y. J. Pendleton and A. G. G. M. Tielens (San Francisco: ASP), 87
Mathis, J. S. "Dust Models with Tight Abundance Constraints", 1996, ApJ, 472, 643
Matthews, L.D.; Gallagher, J.S.; van Driel, 1997, "Exploration of the TF Relationship in LSB Galaxies at the End of the Spiral Sequence," in Dark and Visible Matter in Galaxies, ASP Conference 117, eds. M. Persic & P. Salucci, p. 98
Michalitsianos, A. G., Dolan, J. F., Kazanas, D., Bruhweiler, F. C., Boyd, P.T., Hill, R.J., Nelson, M.J., Percival, J.W., Van Citters, G.W "Ly alpha Absorption-Line Systems in the Gravitational Lens Q0957+561", 1997, ApJ 474, 598
Mould, J. R., Watson, A. M., Gallagher, J. S. and WFPC2 IDT, 1996, "Low Mass Stars in an Outer Field in NGC 6397," PASP, 108, 682.
Mullman, K. L., Sakai, M., and Lawler, J. E. "Absolute transition probabilities for the a6D - y6Po multiplet (#8) of FeII" 1997, A&AS, 122, 157
Nossal, S., F.L. Roesler, M.M. Coakley, and R.J. Reynolds 1997, "Geocoronal hydrogen Balmer-alpha line profiles obtained using Fabry-Perot annular summing spectroscopy: Effective temperature results", JGR, 102, 14541
O'Donnell, J. E., & Mathis, J. S. "Dust Grain Size Distributions and the Abundance of Refractory Elements in the Diffuse Interstellar Medium", 1997, ApJ, 479, 806
O'Brian, T. R., and Lawler, J. E. "Radiative Lifetimes in CI and an atomic carbon beam source" 1997, J. Quant. Spectrosc. Radiat. Transfer, 57, 309
Pinfield, D.J., Hodgkin, S.T., Jameson, R.F., Cossburn, M.R, & von Hippel, T. "Brown Dwarf candidates in Praesepe" 1997, MNRAS, 287, 180
Quirrenbach, A., Bjorkman, K.S., Bjorkman, J.E., Hummel, C.A., Buscher, D.F., Armstrong, J.T., Mozurkewich, D., Elias II, N.M., and Babler, B.L., "Constraints on the Geometry of Circumstellar Envelopes: Optical Interferometric and Spectropolarimetric Observations of Seven Be Stars", 1997, ApJ, 479, 477
Raymond, J.C., Blair, W.P., Long, K.S., Vancura, O., Edgar, R.J., Morse, J., Hartigan, P., and Sanders, W.T., "The Ultraviolet Spectrum of a Face-On Shock Wave in the Vela Supernova Remnant" 1997, ApJ, 482, 881
Reynolds, R.J., "Ionizing the Galaxy", 1997, Science, 277, 1446
Reynolds, R. J. "The Z-Distribution of the Ionized Interstellar Medium", 1997, in the Physics of Galactic Halos, ed., H. Lesh, R.-J. Dettmar, U. Mebold, and R. Schickeiser (Berlin: Akademie Verlag), 57
Rodriguez-Pascual, P.M., and others including L.S. Sparke, "Steps towards Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei: IX Ultraviolet Observations of Fairall 9", 1997, ApJS,110, 9
Roelfsma, P. R., et al., including J. P Cassinelli, "SWS Spectroscopy of dust bands in compact H II regions", 1996, A&A, 315, L289
Savage, B.D. and Sembach, K. R. 1996, "Interstellar Gas-Phase Abundances and Physical Conditions Toward Two Distant High-Latitude Stars" 1996, ApJ, 470, 893
Savage, B.D., Sembach , K.R., and Lu, L. "Absorption by Highly Ionized Interstellar Gas Along Extragalactic and Galactic Sight Lines" 1997, AJ, 113, 2158
Savage, B.D. and Sembach, K.R. " Interstellar Abundances from Absorption Line Observations with the Hubble Space Telescope" 1996, ARAA, 34, 279
Savage, B.D. and Sembach, K.R. "Abundances in the Galactic Halo Gas" 1996, invited review in Cosmic Abundances, eds. S.S. Holt and G. Sonneborn, (San Francisco: ASP Conference Series), 99, 315
Schechter, P.L. and others including L.S. Sparke, "The Quadruple Gravitational Lens PG 1115 + 080: Time Delays and Models",1997, ApJL, 475, 85
Sembach, K.R. and Savage, B.D. "The Gas and Dust Abundances of Diffuse Halo Clouds in the Milky Way" 1996, ApJ , 457, 211
Sembach, K.R., Savage, B.D., & Tripp, T. M. "High Resolution Ultraviolet Observations of the Highly Ionized Gas Toward Radio Loops I and IV" 1997, ApJ, 480, 216
Shepherd, D., Churchwell, E., Willner, D. "A High Resolution Molecular Line Study of the ON2-N Massive Star Formation Region", 1997, ApJ, 482, 355
Smith, M., Cohen, D., Hubeny, I., Plett, K., Basri, G., Johns-Krull, C., MacFarlane, J., & Hirata, R. "Dynamic Processes in Be Star Atmospheres. V. Helium Line Emissions from the Outer Atmosphere of lambda Eridani", 1997, ApJ, 481, 467
Steppers, B.W., & WFPC2 IDT, including Gallagher, J.S., 1997, "The Star Formation History in the Vicinity of NGC 1866 in the Large Magellanic Cloud," PASP, 109, 292S.
Tran, H.D, Filippenko, A.V., Schmidt, G.D., Bjorkman, K.S., Jannuzi, B.T., and Smith, P.S., "Probing the Geometry and Circumstellar Environment of SN1993J in M81", 1997, PASP, 109, 489
Tripp, T. M, Lu, L. and Savage, B.D., "High Signal-to-Noise Echelle Spectroscopy of Quasar Absorption Line Systems in the Direction of HS 1946+7658" 1996, ApJS, 102, 239
Tripp, T. M, Lu, L. and Savage, B.D., "High Signal-to-Noise Echelle Spectroscopy of Quasar Absorption Line Systems in the Direction of HS 1700+6416" 1997, ApJS, 112, 1
von Hippel, T., Bothun, G.D., & Schommer, R.A. "Stellar Populations and the White Dwarf Mass Function: Connections to SNe Ia Luminosities" 1997, AJ, 114, 1154
Wahlgren, G. M., Johansson, S. G., Litzen, U., Gibson, N. D., Cooper, J. C., Lawler, J. E., Leckrone, D. S., and Engleman, R. Jr. "Atomic data for the ReII UV 1 multiplet and the rhenium abundance in the HgMn-type star Chi Lupi", 1997, ApJ, 475, 380
Wakker, B.P., Howk, C., van Woerden, H., Schwarz, U.J., Beers, T.C., Wilhelm, R., Kalberla, P., Danly, L., "The distance to two hydrogen clouds: the high-velocity complex A and the Low-Latitude Intermediate-Velocity cloud", 1996, ApJ, 473, 834
Wakker, B.P., van Woerden, H., "High-velocity clouds", 1997, Annual Review of Astronomy & Astrophysics 35, 217
Wanders, I. and others including L.S. Sparke, "Steps towards Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei: XI Intensive Monitoring of the Ultraviolet Spectrum of NGC 7469", 1997, ApJS, 113, 69
Weitenbeck, A.J., "Cross Identifications in the Region of NGC 1502", 1997, A.J., 114, 222
Wickliffe, M. E., and Lawler, J. E. "Atomic Transition Probabilities for TmI and TmII" 1997, J. Opt. Soc. Am. B 14, 737
Wickliffe, M. E., and Lawler, J. E. "Atomic transition probabilities in NiI" 1997, ApJS, 110, 163
Wolff, M.J., Clayton, G.C., Kim, S-H., Martin, P.G. and Anderson, C.M., "Ultraviolet Interstellar Linear Polarization III. Features", 1997, ApJ, 478, 395
Wood, K., Bjorkman, K.S., and Bjorkman, J.E., "Deriving the Geometry of Be Star Circumstellar Envelopes from Continuum Spectropolarimetry I. The Case of Zeta Tauri", 1997, ApJ, 477, 926
11. Publications submitted and in press
Bailer-Jones, C.A.L., Irwin, M., & von Hippel, T. "Automated Classification of Stellar Spectra. II: Two-Dimensional Classification with Artificial Neural Networks" 1997, MNRAS, submitted.
Bailer-Jones, C.A.L., Irwin, M., Gilmore, G., & von Hippel, T. "Physical Parameterization of Stellar Spectra: The Neural Network Approach" 1997, MNRAS, in press.
Bless, R. C., and Percival, J. "The Bolometric Luminosities of Stars", 1997, invited review at IAU Symposium 189, Fundamental Stellar Properties, ed. T. R. Bedding, A. J. Booth, and J. Davis (Kluwer: Dordrecht), in press.
Borumand, M., Joynt, R., & Kluzniak, W. "Entrainment in a mixture of two superfluids and its effect on the dynamics of neutron stars," in 18th Texas Symposium on Relativistic Astrophysics, in press.
Casey, B.W., Mathieu, R.D., Vaz, L.P.R., Andersen, J. and Suntzeff, N., "The Pre-Main-Sequence Eclipsing Binary TY Coronae Australis: Precise Stellar Dimensions and Tests of Evolutionary Models", 1997, AJ, submitted.
Clarke, D. and Bjorkman, K.S., "On the polarization of Phi Per", 1997, A & A, submitted.
Cole, A.A., et al. (including Gallagher and Hoessel), "Far-Ultraviolet and Visible Imaging of the Nucleus of M32 with WFPC2" 1998, ApJL, in press.
Conselice, C.J., "The Symmetry, Color and Morphology of Galaxies", PASP, Nov. 1997
Curry, J. J., Den Hartog, E. A., and Lawler, J. E. "Radiative Lifetimes of Dy I and Dy II", J. Opt. Soc. Am. B, in press.
Curry, J. J., and Lawler, J. E. "Branching ratio for the 5S2o - 3P2,1 inter-system resonance multiplet in P II", A&A, in press.
Den Hartog, E. A., Curry, J. J., Wickliffe, M. E., and Lawler, J. E. "Spectroscopic Data for the 6s6p 3P1 level of LuII for the Determination of the Solar Lutetium Abundance", Solar Physics, submitted.
Elmegreen, B.G., Wilcots, E.M., & Pisano, D.J. "HI Observations of the Spiral Arm Pattern Speed in the Late Type Barred Galaxy NGC 925", 1997, ApJL, submitted.
Ferguson, H.C., Tanvir, N.R., & von Hippel, T. "Direct Detection of Intergalactic Stars in the Virgo Cluster" 1997, Nature, submitted.
Fox, G.K., Code, A.D., Anderson, C.M., Babler, B.L., Bjorkman, K.S., Johnson, J.J., Meade, M.R., Nordsieck, K.H., Weitenbeck, A.J., and Zellner, N.E.B., "The First Ultraviolet Linear Spectropolarimetry of the Moon", 1997, MNRAS, submitted.
Groot, P.J., with 20 other authors including von Hippel, C. Howk, A. Cole, and D. J. Pisano, "A Search for Optical Afterglow from GRB970828" 1997, ApJ, submitted.
Hoffman, J.L., Nordsieck, K.H., and Fox, G.K., "Spectropolarimetric Evidence for a Bipolar Flow in Beta Lyrae," AJ, submitted.
Howk, J. C. and Savage, B.D. "Extraplanar Dust in the Edge-on Spiral NGC 891" 1997, AJ, December Issue.
Hunter, D.A., Wilcots, E.M., van Woerden, H., Gallagher, J.S., & Kohle, S. "The Nature of the Extended HI Gas Around NGC 4449: The Dr Jekyll/ Mr. Hyde of Irregular Galaxies", 1997, ApJL, submitted.
Jannuzi, B.T and 11 co-authors (including Savage, B.D.) "The Hubble Space Telescope Quasar Absorption Line Key Project XIII: A Census of Absorption Line Systems at Low Redshift" 1998, ApJS, submitted.
Kluzniak, W. "Three-dimensional flow in accretion disks," in 2nd Pacific Rim Conference, K. Chan, K.S. Cheng eds., in press.
Kluzniak, W., & Lee, W.H. "Binary coalescence of a neutron star and a black hole," ApJL, in press.
Kluzniak, W., & M.Ruderman, "The central engine for longer gamma-ray bursts," in 4th Gamma Ray Burst Symposium, C.A. Meegan, P. Cushman, eds., in press.
Lee, W.H., Kluzniak, W. "Gravitational radiation from mergers of black hole--neutron star binaries," in Second Edoardo Amaldi Conference on Gravitational Waves eds., (World Scientific: Singapore), in press.
Lee, W.H., & Kluzniak, W. "Simulations of the Coalescence of a Black Hole with a Neutron Star," in 4th Gamma Ray Burst Symposium, C.A. Meegan, P. Cushman, eds., in press, astro-ph/9709301.
Lu, L. Savage, B.D., Sembach, K.R., Wakker, B.P, Sargent, W.L.W., and Oosterloo, T.A. "The Metallicity and Dust Content of HVC 287.5+22.5+240: Evidence for a Magellanic Clouds Origin 1997, AJ, in press.
MacLow, M.-M., Chang, T.H., Chu, Y.-H., Points, S.D., Smith, R.C., Wakker, B.P., "X-rays from superbubbles in the Large Magellanic Cloud V: The HII complex N11", 1998, ApJ, 492.
Mathis, J. S., Torres-Peimbert, S., & Peimbert, M., "Temperature and Density Fluctuations in Planetary Nebulae", 1998, ApJ, in press.
Mathis, J. S. "The Near-Infrared Interstellar Silicate Bands and Grain Theories", ApJ, submitted.
Mullman, K. L., Cooper, J. C., and Lawler, J. E. "Radiative lifetimes and ultraviolet branching fractions for resonance lines of Co II", Astrophys. J., in press.
Reynolds, R.J. , N.R. Hausen, S.L. Tufte, L.M. Haffner 1997, "Detection of [O I] 6300 Emission from the Diffuse Interstellar Medium", ApJ, in press.
Reynolds, R.J. , Tufte, S.L., Haffner, L.M., Jaehnig, K., and Percival, J.W. 1997, "The Wisconsin H-alpha Mapper (WHAM): A Brief Review of Performance Characteristics and Early Scientific Results", Publ. Ast. Soc. Australia, in press.
Pisano, D.J., Wilcots, E.M., & Elmegreen, B.G. "The HI Distribution and Dynamics in Two Late-Type Barred Spiral Galaxies: NGC 925 & NGC 1744", 1998, AJ, in press.
Savage, B.D., Tripp, T. M., and Lu, L. "The Intervening and Associated O VI Absorption Line Systems in the Ultraviolet Spectrum of H 1821+643" 1998, AJ, submitted.
Savage, B. D. "Halo Gas and Dust at Zero Redshift" 1997, invited review in Structure and Evolution of the Intergalactic Medium from QSO Absorption Lines, ed. P. Petitjean, (13th IAP Colloquium) in press.
Tufte, S.L., Reynolds, R. J., and Haffner, L.M., 1997, ``The WHAM H-alpha Survey'', in Proceedings of the ASP, Astronomy from Antarctica, eds. G. Novak and R.H. Landsberg (ASP), in press.
Van Woerden, H., Wakker, B.P., Schwarz, U.J., Peletier, R.F., Kalberla, P.M.W., "The high-velocity clouds: galactic or extragalactic?", 1997, in IAU Colloquium 166, eds. D. Breitschwerdt, M. Freiberg, "The Local Bubble", Springer Lecture Notes in Physics
Vaz, L.P.R., Andersen, J., Casey, B.W., Clausen, J.V., Mathieu, R.D. and Heyer, I., "Four-colour photometry of eclipsing binaries. XXXIX. Light curves of the pre-main-sequence triple system TY Coronae Australis", 1997, A&AS, submitted.
Wakker, B.P., Murphy, E., van Woerden, H., Dame, T., "A sensitive search for molecular gas in high-velocity clouds", 1997, ApJ, 488.
Wakker, B.P., van Woerden, H., de Boer, K.S., Kalberla, P.M.W, "A lower limit to the distance of HVC complex H", 1998, ApJ, 493.
Walter, F.M., Vrba, F.J., Wolk, S.J., Mathieu, R.D. and Neuhauser, R., "X-Ray Sources in Regions of Star Formation. VI. The R CrA Association as Viewed by EINSTEIN", 1997, AJ, in press.
White III, R. E., Keel, W.C., & Conselice, C.J. "Seeing Galaxies Through Think and Thin I. Direct Opacity Measurements.", ApJ, submitted.
Wilcots, E.M., & Miller, B. "Anatomy of a Starburst: The Interstellar Medium in IC 10", 1997, AJ, submitted.
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