Eight-colour photometry of stars associated with selected Sharpless HII regions at L II 190 : S 252, S 254, S 255, S 257 and 261.
Abstract
We present optical intermediate band photometry in the 13 colour system of selected stars associated with the Sharpless H II regions S 252, S 254, S 255, S 261, and with the diffuse H II region and small galactic cluster NGC 2175s. We also give near infrared photometry of a few stars associated with S 252. We find that LSV + 20° 20 is an infrared source, with a dusty envelope of Td 950 K. The photometric data was used to derive MK spectral types of selected stars embedded in the H II regions, and of the most likely exciting stars of the radio sources S 252 A, B, C, and E. From our data and supplementary data from the literature we also obtain the reddening law for these H II regions, and estimate the distances to S 252, NGC 2l75s, S 254-S 257, and S 261 to be 2.3 ± 0.1, 1.9 ± 0.2, and 1.0 ± 0.2 Kpc, respectively. CCD imagery in the I passband revealed a small cluster of ≃ 21 stars in the bright reflection knot of S 252 (the "Christbaumhaeufchen"), where at least one of its members (S 252b) is a pre-main sequence star. We briefly comment on the interstellar extinction law, and its effect in the photometric MK classification discussed here.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1987
- Bibcode:
- 1987A&A...171..216C
- Keywords:
-
- Galactic Clusters;
- H Ii Regions;
- Infrared Spectra;
- Stellar Color;
- Stellar Spectrophotometry;
- Visible Spectrum;
- Distance;
- Early Stars;
- Interstellar Extinction;
- Pre-Main Sequence Stars;
- Spectrum Analysis;
- Astrophysics