A Search for RR Lyrae Stars in Segue 2 and Segue 3

Type Journal Article
Names Erin Boettcher, Beth Willman, Ross Fadely, Jay Strader, Mariah Baker, Erica Hopkins, Tonima Tasnim Ananna, Emily C. Cunningham, Tim Douglas, Jacob Gilbert, Annie Preston, Andrew P. Sturner
Publication The Astronomical Journal
Volume 146
Issue 4
Pages 94
Journal Abbreviation The Astronomical Journal
Date October 1, 2013
DOI 10.1088/0004-6256/146/4/94;
ISSN 0004-6256
URL http://adsabs.org/2013AJ.146.94B
Library Catalog labs.adsabs.harvard.edu
Abstract We present an extensive search for RR Lyrae (RRL) stars in and around the ultra-faint Milky Way companions Segue 2 and Segue 3. The former (MV = -2.5) appears to be an extremely faint dwarf galaxy companion of the Milky Way. The latter (MV = 0.0) is among the faintest star clusters known. We use B and V band time-series imaging obtained at the WIYN 0.9 m telescope at Kitt Peak National Observatory to search for RRL in these objects. In our Segue 2 observations, we present a previously unknown fundamental mode (RRab) RRL star with a period of P ab = 0.748 days. With this measurement, we revisit the inverse correlation between langP abrang and lang[Fe/H]rang established in the literature for Milky Way dwarf galaxies and their RRL. In this context, the long period of Segue 2's RRab star as well as the known significant spread in metallicity in this dwarf galaxy are consistent with the observed trend in langP abrang and lang[Fe/H]rang. We derive the first robust distance to Segue 2, using both its RRab star and spectroscopically confirmed blue horizontal branch stars. Using [Fe/H] = -2.16 and -2.44 dex, we find d_{RRL} = 36.6^{+2.5}_{-2.4} and 37.7^{+2.7}_{-2.7} kpc assuming [Fe/H] = -2.257 dex, we find d BHB = 34.4 ± 2.6 kpc. Although no RRL were present in the Segue 3 field, we found a candidate eclipsing binary star system.
Tags Galaxies: Dwarf, STARS: DISTANCES, STARS: VARIABLES: GENERAL, galaxies: star clusters: general, techniques: photometric
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