Astronomy and Astrophysics, volume 474, 35-41 (2007/10-4)
The assessment of the near infrared identification of carbon stars. I. The Local Group galaxies WLM, IC 10 and NGC 6822.
BATTINELLI P., DEMERS S. and MANNUCCI F.
Abstract (from CDS):
The selection of AGB C and M stars from NIR colours has been done in recent years using adjustable criteria that are in needs of standardization if one wants to compare, in a coherent manner, properties of various populations. We intend to assess the NIR colour technique to identify C and M stars. We compare the NIR colours of several C stars previously identified from spectroscopy or narrow band techniques in WLM, IC 10 and NGC 6822. We demonstrate that very few M stars have (J-K)0>1.4 but a non negligible number of C stars are bluer than this limit. Thus, counts of M and C stars based on such limit do not produce pure samples. C/M ratios determined from NIR colours must be regarded as underestimates mainly because the M numbers include many warm C stars and also K stars if no blue limit is considered.
galaxies: individual: IC 10 - galaxies: individual: WLM - galaxies: individual: NGC 6822 - stars: carbon - stars: AGB and post-AGB - galaxies: dwarf
VizieR on-line data:
<Available at CDS (J/A+A/474/35): table2.dat table3.dat>
Stars in WLM (table 2) are [BD2004a] NNN in Simbad, stars in IC 10 (table 3) [DBL2004] NNN.