Optical and infrared properties of the newly formed stars in Canis Major R1

Abstract

view Abstract Citations (67) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optical and infrared properties of the newly formed stars in Canis Major R1. Herbst, W. ; Racine, R. ; Warner, J. W. Abstract UBVRIJHKL photometry and MK spectral types have been obtained for stars illuminating nebulae in the CMa RI association. Five stars, including the two classical Herbig emission stars Z CMa and HD 53367, have K - L excesses and/or emission-line spectra indicating the presence of circumstellar matter. A number of stars also have V - K indices larger than expected on the basis of their spectral types and B - V indices, suggesting that a steeper than normal extinction law applies to these stars. The color-magnitude diagram for the association is unusual; many stars over the entire spectral range of the association (B0 to Al) lie more than 1 mag above the zero-age main sequence (ZAMS) in V. The middle and early-type B stars with this property are all variable stars and most have rotationally broadened spectra and/or shell indicators. The stars with K - L excesses all lie well above the ZAMS. An age of 3 x 10 years is suggested for most of the stars, compatible with the suggestion that a supernova explosion triggered star formation in this region. A comparison is made between the observations and theoretical models of pre-main-sequence stars. Some of the latest-type stars (A0-Al) lie close to the ZAMS, suggesting that either (1) star formation in the association was not coeval, or (2) isochrones derived from Iben's pre-main-sequence models do not represent real stellar groups. A bolometric luminosity of Mbol < - 4.3 is derived for Z CMa, implying a core mass of M> 10 M0 and a spectral type of B 1, if the star is on the ZAM S. Subject headings: clusters: associations - stars: early-type - stars: emission-line Publication: The Astrophysical Journal Pub Date: July 1978 DOI: 10.1086/156282 Bibcode: 1978ApJ...223..471H Keywords: Early Stars; Infrared Astronomy; Optical Properties; Stellar Spectrophotometry; A Stars; Astronomical Catalogs; B Stars; Emission Spectra; Main Sequence Stars; Nebulae; Astronomy; Early-Type Stars:Photometry; Emission-Line Stars:Infrared Excesses; Emission-Line Stars:Stellar Associations; Pre-Main-Sequence Stars:Stellar Groups; Stellar Groups: Ages full text sources ADS | data products SIMBAD (37) GCPD (1)