| Type |
Journal Article |
| Names |
S. Stanimirović, J. M. Weisberg, Z. Pei, K. Tuttle, J. T. Green |
| Publication |
The Astrophysical Journal |
| Volume |
720 |
| Issue |
1 |
| Pages |
415-434 |
| Date |
September 1, 2010 |
| Short Title |
Arecibo Multi-epoch H I Absorption Measurements Against Pulsars |
| URL |
http://adsabs.harvard.edu/abs/2010ApJ...720..415S |
| Library Catalog |
NASA ADS |
| Abstract |
We present results from multi-epoch neutral hydrogen (H I) absorption
observations of six bright pulsars with the Arecibo telescope. Moving
through the interstellar medium (ISM) with transverse velocities of
10-150 AU yr-1, these pulsars have swept across 1-200
AU over the course of our experiment, allowing us to probe the existence
and properties of the tiny-scale atomic structure (TSAS) in the cold
neutral medium (CNM). While most of the observed pulsars show no
significant change in their H I absorption spectra, we have identified
at least two clear TSAS-induced opacity variations in the direction of
B1929+10. These observations require strong spatial inhomogeneities in
either the TSAS clouds' physical properties themselves or else in the
clouds' galactic distribution. While TSAS is occasionally detected on
spatial scales down to 10 AU, it is too rare to be characterized by a
spectrum of turbulent CNM fluctuations on scales of
101-103 AU, as previously suggested by some work.
In the direction of B1929+10, an apparent correlation between TSAS and
interstellar clouds inside the warm Local Bubble (LB) indicates that
TSAS may be tracing the fragmentation of the LB wall via hydrodynamic
instabilities. While similar fragmentation events occur frequently
throughout the ISM, the warm medium surrounding these cold cloudlets
induces a natural selection effect wherein small TSAS clouds evaporate
quickly and are rare, while large clouds survive longer and become a
general property of the ISM. |
| Tags |
ISM: clouds, ISM: structure, Line: Profiles |