AGB stars in the Magellanic Clouds I: The C/M ratio

Regions of different metallicity have been identified in the Magellanic Clouds by using the ratio between Asymptotic Giant Branch stars of spectral type C and M. In the Large Magellanic Cloud the ratio appears to decrease radially while in the Small Magellanic Cloud (SMC) there is no clear trend, reflecting either the large extension of the SMC along the line of sight or a more complex star formation history. The distribution of the C/M ratio is clumpy and corresponds to a spread in (Fe/H) of 0.75 dex in both Clouds. There is an indication of increasing C/M ratio, thus decreasing metallicity, towards the Bridge region connecting the two Clouds.

[1]  Harm Jan Habing,et al.  Asymptotic giant branch stars , 2004 .

[2]  L. Staveley-Smith,et al.  Detection of carbon monoxide within the Magellanic Bridge , 2002, astro-ph/0209523.

[3]  A. Lançon,et al.  Carbon star populations in systems with different metallicities: statistics in Local Group galaxies , 2002, astro-ph/0209044.

[4]  U. Heiter,et al.  The elemental abundance pattern of twenty lambda Bootis candidate stars , 2002 .

[5]  M. Shetrone,et al.  VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies. I. Nucleosynthesis and Abundance Ratios , 2002, astro-ph/0211167.

[6]  M. Shetrone,et al.  VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies. II. Implications for Understanding Galaxy Evolution , 2002, astro-ph/0211168.

[7]  M. Cioni,et al.  Variability and spectral classification of LMC giants: Results from DENIS and EROS , 2001, astro-ph/0109014.

[8]  M. Cioni.  AGB stars and other red giants in the Magellanic Clouds , 2001 .

[9]  M. Cioni,et al.  Magellanic Cloud Structure from Near-Infrared Surveys. I. The Viewing Angles of the Large Magellanic Cloud , 2001, astro-ph/0105339.

[10]  M. Kontizas,et al.  A Catalogue of carbon stars in the LMC , 2001 .

[11]  M. Shetrone,et al.  Abundance Patterns in the Draco, Sextans, and Ursa Minor Dwarf Spheroidal Galaxies , 2000, astro-ph/0009505.

[12]  W. Kunkel,et al.  A Carbon Star Survey of the Local Group Dwarf Galaxies. I. IC 1613 , 2000 .

[13]  A. Robin,et al.  The DENIS Point Source Catalogue towards the Magellanic Clouds , 2000, astro-ph/0003177.

[14]  M. Weinberg,et al.  Stellar Populations in the Large Magellanic Cloud from 2MASS , 2000, astro-ph/0003012.

[15]  E. Grebel,et al.  A New Culprit in the Second-Parameter Problem in the Sculptor Dwarf Spheroidal Galaxy? , 1999, astro-ph/9907156.

[16]  M. Schultheis,et al.  ISOGAL survey of Baade's Windows in the mid-infrared , 1999, astro-ph/9904010.

[17]  D. Martinez-Delgado,et al.  The Star Formation History of the Local Group Dwarf Elliptical Galaxy NGC 185. I. Stellar Content , 1998 .

[18]  N. Epchtein,et al.  The Deep Near Infrared Southern Sky Survey (denis): Progress Status and Scientific Achievements , 1997 .

[19]  H. Richer,et al.  Late-Type Stars in M31. I. Photometric Study of AGB Stars and Metallicity Gradients , 1995, astro-ph/9503048.

[20]  E. D. Friel,et al.  The Old Open Clusters of the Milky Way , 1995 .

[21]  M. Feast,et al.  Carbon and M-type stars in the outer haloes of the Magellanic Clouds , 1994 .

[22]  R. Kirshner,et al.  Optical Emission-Line Properties of M33 Supernova Remnants , 1993 .

[23]  John P. Huchra,et al.  Extragalactic globular clusters. II, The M31 globular cluster system , 1991 .

[24]  J. Frogel,et al.  The Large Magellanic Cloud Bar West field , 1990 .

[25]  B. Madore,et al.  An empirical test for the metallicity sensitivity of the Cepheid period-luminosity relation , 1990 .

[26]  K. Cook,et al.  Carbon and M Stars in Nearby Galaxies: A Preliminary Survey Using a Photometric Technique , 1986 .

[27]  J. Mould,et al.  The evolution of asymptotic giant branch stars in the Large Magellanic Cloud. II. Spectroscopy of a complete sample. , 1985 .

[28]  V. Blanco,et al.  The distribution of carbon and M-type giants in the Magellanic Clouds. , 1983 .

[29]  I. Iben,et al.  Asymptotic Giant Branch Evolution and Beyond , 1983 .

[30]  D. Lambert,et al.  Lithium in late-type giants. II. 31 M giants and supergiants , 1982 .

[31]  B. Westerlund.  The Magellanic Clouds , 1997 .

[32]  V. Blanco,et al.  Carbon and late M-type stars in the Magellanic Clouds , 1980 .

[33]  L. Vigroux.  The Magellanic Clouds. , 1979 .

[34]  S. Nagasawa.  Tokyo Astronomical Observatory , 1967 .