Open AccessThe red giant branch tip and bump of the Leo II dwarf spheroidal galaxy
Author(s) -
Bellazzini M.,
Gennari N.,
Ferraro F. R.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09027.x
Subject(s) - physics , red giant branch , astrophysics , rr lyrae variable , horizontal branch , globular cluster , asymptotic giant branch , red clump , galaxy , astronomy , dwarf spheroidal galaxy , population , stars , stellar population , giant star , metallicity , luminosity function , dwarf galaxy , photometry (optics) , luminosity , star formation , interacting galaxy , medicine , environmental health
We present V and I photometry of a 9.4 × 9.4 arcmin 2 field centred on the dwarf spheroidal galaxy Leo II. The tip of the red giant branch (TRGB) is identified at I TRGB = 17.83 ± 0.03 and adopting 〈[M/H]〉=−1.53 ± 0.2 from the comparison of RGB stars with Galactic templates, we obtain a distance modulus ( m − M ) 0 = 21.84 ± 0.13 , corresponding to a distance D = 233 ± 15 kpc . Two significant bumps have been detected in the luminosity function of the RGB. The fainter bump (B1, at V = 21.76 ± 0.05 ) is the RGB bump of the dominant stellar population while the actual nature of the brightest one (B2, at V = 21.35 ± 0.05 ) cannot be firmly assessed on the basis of the available data; it may be due to the asymptotic giant branch clump of the main population or it may be a secondary RGB bump. The luminosity of the main RGB bump (B1) suggests that the majority of RGB stars in Leo II belong to a population that is ≳4 Gyr younger than the classical Galactic globular clusters. The stars belonging to the He‐burning red clump are shown to be significantly more centrally concentrated than RR Lyrae and blue horizontal branch stars, probing the existence of an age/metallicity radial gradient in this remote dwarf spheroidal.