2019ApJ...872..140D -
Astrophys. J., 872, 140-140 (2019/February-3)
Ultraviolet HST spectroscopy of Planck Cold clumps.
DIRKS C. and MEYER D.M.
Abstract (from CDS):
We report results of the first study utilizing the ultraviolet capabilities of the Hubble Space Telescope to investigate a sample of Planck Galactic Cold Clump (PGCC) sources. We have selected high-resolution spectra toward 25 stars that contain a multitude of interstellar absorption lines associated with the interstellar medium (ISM) gas within these PGCC sources, including carbon monoxide (CO), C I and O I. By building cloud-component models of the individual absorption components present in these spectra, we can identify and isolate components associated with the PGCC sources, allowing for a more accurate investigation of the ISM behavior within these sources. Despite probing a broad range of overall sightline properties, we detect CO along each sightline. Sightlines with CO column density N(CO) > 1015 cm–2 exhibit spatial dependence in N(CO) and CO/C I, while sightlines with N(CO) < 1015 cm–2 show no such spatial dependence. Differences between N(H2) values derived from UV absorption and dust emission suggest structure in the spatial distribution of N(H2), where "CO-bright" sightlines are associated with PGCC sources embedded within smooth translucent envelopes, and "CO-dark" sightlines are associated with PGCC sources embedded in patchier environments containing more diffuse gas.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
dust, extinction - ISM: atoms - ISM: clouds - ISM: molecules
Simbad objects:
49
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