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Near-infrared and ISOCAM observations of the Chamaeleon II dark cloud
An infrared study including ISOCAM images at 6.75 and 14.3 mu m of alarge portion (28 arcmin x 26 arcmin) of the Chamaeleon II dark cloudand sub-arcsec resolution JHKs images of the central (4.9arcmin x 4.9 arcmin) area is presented. Combining the ISOCAMobservations with J and Ks photometry obtained with DENIS, wehave found 12 young stars, of which 8 are previously identified sources.Of the new candidate YSOs, ISO-ChaII13 shows a clear mid-IR excess withan infrared luminosity of ~ 0.02 Lsun and a stellarluminosity >=0.01 Lsun. This last value of luminositycorresponds to that expected for a sub-stellar object with an agebetween 1-10 Myr. The analysis of the J-H/H-K diagram of the sourcesdetected in the central part of the dark cloud has allowed us toidentify 10 very faint sources not found by ISOCAM with possible near-IRexcesses that may be embedded young brown dwarfs. Finally, the center ofthe dark cloud is characterized by the presence of the Class I YSO IRAS12553-7651 (ISO-ChaII28) with Lbol= 1.49 Lsun, andassociated with a faint nebulosity observed at 2.2 mu m.Based on observations collected at the European Southern Observatory,Chile, ESO proposal N.65.I-0054, CTIO(Chile), and ISOCAM observationsN.11500619, and 11500620.Tables 1 and 2 are only available in electronic at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp:cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/995
| On the distance to the Chamaeleon I and II associations
Constraints on the distances to the dark clouds Chamaeleon I and II areinvestigated in detail. A compilation of photometric data, spectraltypes and absolute magnitudes for field stars towards each cloud ispresented, and results are used to examine the distribution of reddeningwith distance along each line of sight. The distances to starsassociated with reflection nebulae in each cloud are examined in detail.On the basis of these results, we deduce the most probable distance ofCha I to be 160+/-15pc, and that of Cha II to be 178+/-18pc. Anexamination of the mean fluxes of T Tauri stars in each cloud providesindependent evidence to suggest that Cha II is significantly moredistant than Cha I. Both clouds appear to be embedded in a macroscopicsheet-like structure extending over much of the Chamaeleon-Musca-Cruxregion. The Chamaeleon III and DC\ts 300.2--16.9 clouds are probablypart of the same structure, with probable distances ~ 140--160pc.
| Chamaeleon II - Distance determination and HR diagram
Photometric and spectroscopic observations of the classical T Tauristars in the Chamaeleon II dark cloud are presented. The distance to ChaII is 200 +/- 20 pc, based on a plot of extinction versus distance forfield stars seen against the cloud. The ages of the premain-sequencestars in Cha II range between 10 exp 5 and 10 exp 7 yr. The stellarpopulation of the Cha II cloud consists mostly of low mass stars - atleast 17 of the 19 known T Tauri stars in Cha II have masses less than 1solar mass. The only intermediate mass star in the cloud is IRAS12496-7650, a highly embedded Herbig Ae star. The mass function of ChaII resembles that of the Lupus complex, and there are a larger fractionof low mass stars in Cha II than there are in the Taurus-Auriga region.
| List of errors found in the Yale Zone Catalogues, the GC, and the Cape Photographic Catalogues
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| Takýmyýldýz: | Bukalemun |
| Sað Açýklýk: | 13h03m30.92s |
| Yükselim: | -77°01'53.8" |
| Görünürdeki Parlaklýk: | 9.403 |
| özdevim Sað Açýklýk: | -17.4 |
| özdevim Yükselim: | -4.3 |
| B-T magnitude: | 9.593 |
| V-T magnitude: | 9.419 |
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