2024-03-28T18:03:04Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/2158582020-12-10T15:56:16Zcom_10261_97com_10261_4col_10261_350
Ball, Catherine
Cannon, John M.
Leisman, Lukas
Adams, Elizabeth A. K.
Haynes, Martha P.
Józsa, Gyula I. G.
McQuinn, Kristen B. W.
Salzer, John J.
Brunker, Samantha
Giovanelli, Riccardo
Hallenbeck, Gregory
Janesh, William
Janowiecki, Steven
Jones, Michael G.
Rhode, Katherine L.
2020-07-02T09:40:04Z
2020-07-02T09:40:04Z
2018
Astronomical Journal 155(2): 65 (2018)
http://hdl.handle.net/10261/215858
10.3847/1538-3881/aaa156
http://dx.doi.org/10.13039/100000001
http://dx.doi.org/10.13039/501100000923
http://dx.doi.org/10.13039/100001008
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003329
We present new high-resolution H i spectral line imaging of Coma P, the brightest H i source in the system HI 1232+20. This galaxy with extremely low surface brightness was first identified in the ALFALFA survey as an >(Almost) Dark> object: a clearly extragalactic H i source with no obvious optical counterpart in existing optical survey data (although faint ultraviolet emission was detected in archival GALEX imaging). Using a combination of data from the Westerbork Synthesis Radio Telescope and the Karl G. Jansky Very Large Array, we investigate the H i morphology and kinematics at a variety of physical scales. The H i morphology is irregular, reaching only moderate maxima in mass surface density (peak pc-2). Gas of lower surface brightness extends to large radial distances, with the H i diameter measured at 4.0 ±0.2 kpc inside the pc-2 level. We quantify the relationships between mass surface density of H i gas and star formation on timescales of ∼100-200 Myr as traced by GALEX far-ultraviolet emission. While Coma P has regions of dense H i gas reaching the cm-2 level typically associated with ongoing star formation, it lacks massive star formation as traced by Hα emission. The H i kinematics are extremely complex: a simple model of a rotating disk cannot describe the H i gas in Coma P. Using spatially resolved position-velocity analysis we identify two nearly perpendicular axes of projected rotation that we interpret as either the collision of two H i disks or a significant infall event. Similarly, three-dimensional modeling of the H i dynamics provides a best fit with two H i components. Coma P is just consistent (within 3σ) with the known scaling relation. It is either too large for its H i mass, has too low an H i mass for its H i size, or the two H i components artificially extend its H i size. Coma P lies within the empirical scatter at the faint end of the baryonic Tully-Fisher relation, although the complexity of the H i dynamics complicates the interpretation. Along with its large ratio of H i to stellar mass, the collective H i characteristics of Coma P make it unusual among known galaxies in the nearby universe. © 2018. The American Astronomical Society. All rights reserved.
openAccess
Galaxies: dwarf
Galaxies: evolution
Galaxies: individual (Coma P, AGC 229385)
Galaxies: irregular
The Enigmatic (Almost) Dark Galaxy Coma P: The Atomic Interstellar Medium
artículo