IDENTIFICATION OF 106 NEW INFRARED CARBON STARS IN THE IRAS POINT-SOURCE CATALOG - NEAR-INFRARED PHOTOMETRY AND THEIR SPACE DISTRIBUTION IN THE GALAXY
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Date
1993
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Abstract
This paper reports on JHKLM observations of 1332 IRAS evolved stars with thick dust and gas envelopes, selected according to their colour properties. These observations were primarily aimed at identifying, with an original method, new distant carbon stars suspected to experience high mass loss (Infrared Carbon Stars or IRCS). Combining the measured K - L colour with the IRAS [12 - 25] colour, we recognized more than 100 new candidates. Several new results on the space distribution of IRCS are drawn out. Their surface number density is estimated to be approximately 12 per kpc2 and is shown to be constant in the galactocentric distance range 5-11 kpc with a scale height of 190 pc. No star is found to belong to the bulge population and their number density might present a cut off at about 4 kpc from the Sun toward the galactic center direction. IRCS represent approximately 25 % of the total number of carbon stars. As they lose mass at a rate in the range of 10(-6) - 10(-5) M./year which is 10 to 100 times larger than the average rate of ''optical'' carbon stars, IRCS are the major contributors to the enrichment of the interstellar medium in heavy elements processed in carbon stars. We evaluate a rate of restitution by carbon stars of approximately 10(-4) M./year/kpc2. Finally, our large set of near-IR data is used to test the completeness of the 4th edition of the General Catalogue of Variable Stars for IRAS samples.
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STARS-CARBON, CIRCUMSTELLAR MATTER, MASS-LOSS, ASYMPTOTIC GIANT BRANCH, GALAXY-STELLAR CONTENT, INFRARED-STARS