A study of the Chamaeleon dark cloud and T-association -I.Extinction, distance and membership.
Abstract
The results of an observing program to investigate the nature and degree of reddening of a number of stars in the field towards the dark cloud and T-association in Chamaeleon are presented. The observations comprise optical (UBVRI) and infrared (JHK) photometry, and optical spectroscopy. New and previously published data are combined to assess membership criteria for 110 stars, and separate catalogues of association members and field stars are presented. Optical identifications are listed for 27 IRAS point sources in the region. The reddening/distance relation for field stars indicates a distance to the cloud of 140 + or - 12 pc. This result confirms that the extinction law is anomalous towards some stars in the cloud, notably the embedded A0 ZAMS star HD 97300, with values of up to 5.5 for the ratio of total-to-selective extinction. A comparison of 21-cm data with the reddening of background field stars indicates that the ratio N(H I)/E(B-V) is significantly less than the interstellar mean, indicating that most of the hydrogen in the cloud is molecular.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 1987
- DOI:
- 10.1093/mnras/224.2.497
- Bibcode:
- 1987MNRAS.224..497W
- Keywords:
-
- Dark Matter;
- Interstellar Extinction;
- Molecular Clouds;
- Star Distribution;
- Stellar Evolution;
- T Tauri Stars;
- Distance;
- Infrared Spectra;
- Stellar Spectrophotometry;
- Ubv Spectra;
- Astrophysics