Reddenings and metallicities in the LMC and SMC from Stromgren CCD photometry

Citation
Ss. Larsen et al., Reddenings and metallicities in the LMC and SMC from Stromgren CCD photometry, ASTRON ASTR, 364(2), 2000, pp. 455-466
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
364
Issue
2
Year of publication
2000
Pages
455 - 466
Database
ISI
SICI code
0004-6361(200012)364:2<455:RAMITL>2.0.ZU;2-B
Abstract
The individual reddenings for B stars in two fields in the Small Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determi ned by means of Stromgren vvby CCD photometry. In both LMC fields we find a foreground reddening of E(B - V) = 0.085 +/- 0.02, and for the SMC fields we find E(B - V) = 0.070+/-0.02. In addition to the foreground reddening we find contributions from reddening intrinsically in the Clouds up to E(B - V) similar to 0.21. The intrinsic contribution is not correlated with posit ion within our similar to 6' x 4.'5 CCD fields but varies in an essentially random way. Unless the reddening is measured for a particular object, it w ill be uncertain by +/-0.035 (best case, far from the central bars) to more than +/-0.10 (close to the central bars). The Stromgren vby photometry has been used to derive metallicities for GK g iant stars in the observed fields. Adopting average reddenings we obtain me an metallicities which are consistent with those found from spectroscopic s tudies of F and G supergiants (Westerlund 1997), but with a considerable sc atter in the derived metallicities, from [Fe/H] approximate to -2.0 to [Fe/ H] greater than or similar to 0. A significant fraction of the scatter is, however, due to reddening variations rather than being intrinsic. The possi ble existence of high metallicity stars should be investigated further usin g spectroscopic methods.