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A Census of the Chamaeleon I Star-forming Region
I present a new census of the members of the Chamaeleon I star-formingregion. Optical spectroscopy has been obtained for 179 objects that havebeen previously identified as possible members of the cluster, that lackeither accurate spectral types or clear evidence of membership, and thatare optically visible (I<~18). I have used these spectroscopic dataand all other available constraints to evaluate the spectralclassifications and membership status of a total sample of 288 candidatemembers of Chamaeleon I that have appeared in published studies of thecluster. The latest census of Chamaeleon I now contains 158 members,eight of which are later than M6 and thus are likely to be brown dwarfs.I find that many of the objects identified as members of Chamaeleon I inrecent surveys are actually field stars. Meanwhile, seven of ninecandidates discovered by Carpenter and coworkers are confirmed asmembers, one of which is the coolest known member of Chamaeleon I at aspectral type of M8 (~0.03 Msolar). I have estimatedextinctions, luminosities, and effective temperatures for the membersand used these data to construct an H-R diagram for the cluster.Chamaeleon I has a median age of ~2 Myr according to evolutionary modelsand hence is similar in age to IC 348 and is slightly older than Taurus(~1 Myr). The measurement of an initial mass function for Chamaeleon Ifrom this census is not possible because of the disparate methods withwhich the known members were originally selected and must await anunbiased, magnitude-limited survey of the cluster.Based on observations performed at Las Campanas Observatory. Thispublication makes use of data products from the Two Micron All SkySurvey, which is a joint project of the University of Massachusetts andthe Infrared Processing and Analysis Center/California Institute ofTechnology, funded by the National Aeronautics and Space Administrationand the National Science Foundation.
| A study of the Chamaeleon I dark cloud and T-association. III - Near-infrared photometry of IRAS-selected field stars
Results of a program of ground-based near-infrared (JHKL) photometry arepresented for 28 IRAS-selected sources in Chamaeleon I unassociated withpreviously known members of the pre-main-sequence population.Ground-based data are combined with IRAS results (including those fromthe Serendipitous Survey data base) to investigate the nature andevolutionary status of the sample. A search for highly reddenedbackground stars was unsuccessful, but four previously unrecognizedyoung embedded stars were identified of which one (11057 - 7706) maystill be in the accretion phase. Serendipitous Survey data have alsobeen extracted for opically selected members of the T-association, andIRAS identifications for several which do not appear in the Point SourceCatalog are reported. The total number of young stars in Chamaeleon Idetected as point sources by IRAS is now 36.
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| Takýmyýldýz: | Bukalemun |
| Sað Açýklýk: | 11h24m51.67s |
| Yükselim: | -76°36'42.6" |
| Görünürdeki Parlaklýk: | 9.221 |
| özdevim Sað Açýklýk: | 9.6 |
| özdevim Yükselim: | -1 |
| B-T magnitude: | 10.913 |
| V-T magnitude: | 9.361 |
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