1. An early-type galaxy with an inner star-forming disk
- Author
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Songlin Li, Yanmei Chen, Longji Bing, Dmitry Bizyaev, Xiaoling Yu, Martha Tabor, Jianhang Chen, and Yong Shi
- Subjects
Physics ,010308 nuclear & particles physics ,Star formation ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Star (graph theory) ,01 natural sciences ,Astrophysics - Astrophysics of Galaxies ,Accretion (astrophysics) ,Galaxy ,Early type ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
Early-type galaxies (ETGs) are composed of two distinct populations: high-mass and low-mass, which are likely to be built via gas-poor merging and gas-rich merging/accretion, respectively. However, it is difficult to directly associate low-mass ETGs with gas-rich processes, because currently they are gas poor with no signs of ongoing star formation. We report a discovery of an ETG (SDSS J142055.01+400715.7) with Mstellar=10^10 Msun that offers direct evidence for gas-rich merging as the origin of low-mass ETGs. The integrated properties of the galaxy are consistent with a typical low-mass ETG, but the outer and inner regions show distinct dispersion- and rotation-dominated kinematics, respectively. There are some tidal features surrounding the galaxy. These two facts suggest very recent galaxy merging. Furthermore, the inner disk harbors on-going star formation, indicating the merging to be gas rich. This type of galaxy is rare but it may be a demonstration of the role the transient phase of gas-rich merging plays in making a low-mass ETG., 6 pages, 6 figures, accepted for publication in MNRAS
- Published
- 2018