A detection of gas associated with the M31 Stellar Stream

Koch, Andreas and Danforth, Charles W. and Rich, R. Michael and Ibata, Rodrigo A. and Keeney, Brian A. (2015) A detection of gas associated with the M31 Stellar Stream. The Astrophysical Journal, 807 (2). ISSN 0004-637X

[thumbnail of 1506.00635]
PDF (1506.00635)
1506.00635.pdf - Accepted Version
Available under License Creative Commons Attribution.

Download (671kB)


Detailed studies of stellar populations in the halos of the Milky Way and the Andromeda (M31) galaxies have shown increasing numbers of tidal streams and dwarf galaxies, attesting to a complicated and on-going process of hierarchical structure formation. The most prominent feature in the halo of M31 is the Giant Stellar Stream, a structure ~4fdg5 in extent along the sky, which is close to, but not coincident with the galaxy's minor axis. The stars that make up this stream are kinematically and chemically distinct from the other stars in the halo. Here, we present Hubble Space Telescope/Cosmic Origins Spectrograph high-resolution ultraviolet absorption spectra of three active galactic nuclei sight lines which probe the M31 halo, including one that samples gas in the main southwestern portion of the Giant Stream. We see two clear absorption components in many metal species at velocities typical of the M31 halo and a third, blueshifted component which arises in the stream. Photoionization modeling of the column density ratios in the different components shows gas in an ionization state typical of that seen in other galaxy halo environments and suggests solar to slightly super-solar metallicity, consistent with previous findings from stellar spectroscopy.

Item Type:
Journal Article
Journal or Publication Title:
The Astrophysical Journal
Additional Information:
This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/0004-637X/807/2/153
Uncontrolled Keywords:
ID Code:
Deposited By:
Deposited On:
30 Nov 2016 14:48
Last Modified:
20 Sep 2023 00:58