Open AccessIs there a metallicity gradient in the Large Magellanic Cloud?
Author(s) -
Feast Michael W.,
Abedigamba Oyirwoth P.,
Whitelock Patricia A.
Publication year - 2010
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2010.00933.x
Subject(s) - metallicity , astrophysics , large magellanic cloud , physics , stars , rr lyrae variable , asymptotic giant branch , population , star cluster , astronomy , small magellanic cloud , globular cluster , demography , sociology
A small but significant radial gradient in the mean periods of Large Magellanic Cloud (LMC) RR Lyrae variables is established from the OGLE‐III survey data. This is interpreted as a metallicity gradient but other possibilities are also discussed. Data on the ratio of photometrically selected C‐ and M‐type asymptotic giant branch (AGB) stars in the LMC, kindly provided by M‐R. L. Cioni, are reanalysed. Removing the effects of bias leads to conclusions strikingly different to the original ones. There is a slight gradient of the C/M ratio in the inner part of the LMC, which might be due to a very small mean metallicity gradient. In the outer part of the LMC the C/M ratio drops dramatically. The most likely reason for this is that the proportion of older stars increases in the outer regions. The mean metallicity of the inner AGB star population estimated from the C/M ratio is lower than for intermediate age LMC clusters and suggest that this population is in the mean older than the clusters and has a mean age which falls in the LMC cluster age gap.