Open AccessThe brightest asymptotic giant branch stars in the Leo I dwarf spheroidal galaxy
Author(s) -
Menzies John,
Feast Michael,
Tanabé Toshihiko,
Whitelock Patricia,
Nakada Yoshikazu
Publication year - 2002
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 - 10.1046/j.1365-8711.2002.05759.x
Subject(s) - physics , asymptotic giant branch , astrophysics , carbon star , stars , astronomy , large magellanic cloud , galaxy , dwarf galaxy
The first results of a study of the dwarf spheroidal galaxy Leo I using the new Nagoya–South African Infrared Survey Facility (IRSF) are presented. J , H and K s observations show that most, if not all, of at least the top magnitude of the asymptotic giant branch (AGB) in K s is populated by carbon stars. In addition there are five very red objects which are believed to be dust‐enshrouded AGB stars. One of these is, remarkably, well outside the main body of the galaxy. Three of these obscured stars and five known carbon stars show variability in observations 11 months apart. One of the obscured stars has Δ K s = 0.87 , making it highly likely that it, at least, is a Mira variable. The tip of the AGB is at M bol ∼−5.1 , but further variability studies are necessary to obtain a definitive value. Comparison with carbon stars, both Miras and non‐Miras, in Magellanic Cloud clusters, and taking into account other evidence on the ages and metallicities of Leo I populations, suggests that these obscured stars belong to the youngest significant population of Leo I and have ages of ∼2 Gyr.