A search for OB stars in the field of the galactic OB association Bochum 7

Abstract

Context. The presence of a Wolf-Rayet star, WR12, at α = 8 h 44 m 47.2 s , δ = −45 • 58 55.5 (J2000.0), triggered the search for a surrounding OB association now known as Bochum 7. Several papers have dealt with the existence of Bo 7, but none actually included spectral types of the stars. To assure the spectral types of members of the association, it is essential to have spectral images of them. Aims. In this paper we present previously unpublished spectra of OB stars over a 30 arcmin field covering the estimated field of the galactic OB association. Methods. From UBV aperture photometry, OB star candidates were selected, and optical spectroscopic observations were obtained for these in CASLEO, Argentina. Results. 63 stars were classified as OB type, including 8 stars already present in the LSS catalogue, and 37 of these 63 stars did not have a well-known spectral type. The OB stars were used to test the properties of the interstellar dust in the line of sight and the relation between the diffuse interestelar band at 4428 Å, which grows linearly with E (B−V) until 1 mag. Combining our data with 2MASS IR photometry we tested and confirmed that derivation of stellar parameters from our photometry, using the CHORIZOS code, is highly reliable.

The massive eclipsing system ALS 1135 and variable stars in the field of the distant OB association Bochum 7

“…The E(B − V ) colour excess amounts to 0.20-0.45 mag for Vel OB1 and 0.75-1.05 mag for Bochum 7. From the U BV observations of practically the same field made by Corti et al (2007) the following ranges of E(B −V ) can be estimated: 0.25-0.48 mag for Vel OB1 and 0.58-1.0 mag for Bochum 7, in good agreement with Sung et al (1999). It is obvious that the spread of reddening in our small field will be much smaller.…”

“…As mentioned above, the field we observed contains stars from at least two OB associations, Vel OB1 and Bochum 7. Sung et al (1999) and Corti et al (2007) observed much larger field than we did, 30 × 30 , roughly covering the area shown in Fig. 1.…”

“…Despite the fact that the MIKE spectrum was taken close to . Open circles and squares represent stars belonging to Vel OB1 and Bochum 7 (Vel OB3), respectively, identified using the photometry and spectroscopy of Corti, Bosch, & Niemela (2007). The bright star on the left is HR 3487 (a Vel).…”

GS263-02+45: a new HI supershell with evidence of having triggered star formation?

“…(Corti 2005). In the above listing the prefix LS stands for stars listed in the LSS Catalogue (Stephenson & Sanduleak 1971), while CBN indicates those stars identified by Corti et al (2007). Following the guidelines of the IAU, CBN stars are identified using the capitalized first letters of the last names of the authors followed by GALACTIC LAT.…”

Effective temperature of ionizing stars in extragalactic H iiregions – II. Nebular parameter relationships based on CALIFA data

“…For ionizing stars of nearby H II regions, located in the Milky Way and the Magellanic Clouds, the effective temperature can be directly estimated by using their photometric and spectrometric data (e.g. Massey et al 2005Massey et al , 2009Corti et al 2007;Sota et al 2011;Morrell et al 2014;Walborn et al 2014;Lamb et al 2016;Evans et al 2015;Mohr-Smith et al 2017;Martins & Palacios 2017;Markova et al 2018). However, for the majority of the distant ionizing massive stars, T eff can only be indirectly estimated, e.g.…”