BST1047+1156:an extremely diffuse and gas-rich object in the Leo I group
| Autor: | Mihos, J. C. (J. Christopher), Carr, C. T. (Christopher T.), Watkins, A. E. (Aaron E.), Oosterloo, T. (Tom), Harding, P. (Paul) |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
interactions [galaxies]
structure [galaxies] Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics irregular [galaxies] groups: individual (Leo I) [galaxies] Astrophysics::Galaxy Astrophysics evolution [galaxies] |
| Popis: | We report the detection of diffuse starlight in an extragalactic H ɪ cloud in the nearby Leo I galaxy group. We detect the source, BST1047+1156, in both broadband optical and the Galaxy Evolution Explorer (GALEX) ultraviolet (UV) light. Spanning ~2 kpc in radius, it has a peak surface brightness of μB = 28.8 mag arcsec⁻², making it the lowest surface brightness object ever detected via integrated light. Although the object is extremely gas rich, with a gas fraction of fg = 0.99, its peak H ɪ column density is well below levels where star formation is typically observed in galaxies. Nonetheless, BST1047+1156 shows evidence for young stellar populations: along with the detected UV emission, the object is extremely blue, with B − V = 0.14 ± 0.09. The object has two tidal tails and is found embedded within diffuse gas connecting the spiral galaxy M96 to the group’s extended H ɪ Leo Ring. The nature of BST1047+1156 is unclear. It could be a disrupting tidal dwarf, recently spawned from star formation triggered in the Leo I group’s tidal debris. Alternatively, the object may have been a pre-existing galaxy—the most extreme example of a gas-rich field low surface brightness galaxy known to date—which had a recent burst of star formation triggered by encounters in the group environment. |
| Databáze: | OpenAIRE |
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