A search for OB stars in the field of the galactic OB association Bochum\,7 I. UBV-IR photometry and optical spectroscopy

CORTI, M., BOSCH, G., NIEMELA, V.

ASTRONOMY AND ASTROPHYSICS

Año: 2006

0004-6361

The presence of a Wolf-Rayet star, WR12, at $alpha$ =8$^h$44$^m$47.2$^s$, $delta$ = - 45$^{circ}$58arcmin55.5arcsec(J2000.0), triggered the search for a surrounding OB associationnow known as Bochum,7. Several papers have dealt with the existence of Bo,7,but none actually included spectral types of the stars. In order toassure the spectral types of members of the Association, it is essential to have spectral images of them. In this paper we present previously unpublished spectra ofOB stars over a 30 arcmin field covering the estimated field of thegalactic OB association. From UBV imaging obtained at CTIO, Chile, aperture photometrywas obtained to selectcandidates and optical spectroscopic observations were obtained inCASLEO, Argentina, for over one hundred stars. 63 stars were classified as OB type, including 8 stars already presentin the LSS catalogue and 37 of this 63 stars did not havewell-known spectral type. The OB stars were used to test theproperties of the interstellar dust in the line of sight and therelation between the diffuse interestelar band at 4428,AAwhich grows linearly with E$_{(B-V)}$ until 1 mag.Combining our data with 2MASS IRphotometry we {f tested and confirmed that derivation of stellarparameters from our photometry,using the CHORIZOS code, is highlyreliable.