Dwarf irregular galaxy Leo A extends even farther, according to HST WFC3 photometry

Autor:	Rokas Naujalis, R. Stonkutė, Alina Leščinskaitė, Vladas Vansevičius, Marius Čeponis
Rok vydání:	2018
Předmět:	Physics Stellar mass 010308 nuclear & particles physics Metallicity Local Group Astronomy and Astrophysics Astrophysics 01 natural sciences Galaxy Red-giant branch Photometry (astronomy) Leo A Space and Planetary Science 0103 physical sciences Irregular galaxy 010303 astronomy & astrophysics
Zdroj:	Astronomy & Astrophysics. 614:A144
ISSN:	1432-0746 0004-6361
DOI:	10.1051/0004-6361/201731840
Popis:	Context. Leo A is an isolated gas-rich dwarf irregular galaxy of low stellar mass and metallicity residing at the outskirts of the Local Group. Ages of the stellar populations in Leo A range from ~10 Myr to ~10 Gyr. A large stellar halo (up to the deprojected distance of ~1.7 kpc) was discovered based on Subaru wide-field photometry of red giant branch stars.Aims. We aim to study stellar populations at the very outer region of the Leo A galaxy.Methods. We analysed HST WFC3 archive observation data in the field that is partly located beyond the previously known limits of the Leo A galaxy. We performed photometry of star-like objects in theF475WandF814Wpassbands and studied the spatial distribution of the Leo A stars below the horizontal branch.Results. We report a discovery of stellar halo populations (subgiants and faint red giants) in the Leo A galaxy extending up to ~2.3 kpc deprojected distance from the galaxy centre. Analysis of the colour-magnitude diagram suggests old (>5 Gyr) stellar populations of very low metallicity (Z~ 0.0001).
Databáze:	OpenAIRE
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