The VLT-FLAMES Tarantula Survey
XVI. The optical and NIR extinction laws in 30 Doradus and the photometric determination of the effective temperatures of OB stars⋆
1 Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, 18 008 Granada, Spain
2 UK Astronomy Technology Centre, Royal Observatory Edinburgh Blackford Hill, Edinburgh, EH9 3HJ, UK
3 Departamento de Física, Universidad de La Serena, Av. Cisternas 1200 Norte, La Serena, Chile
4 Armagh Observatory, College Hill, Armagh BT61 9DG, UK
5 Department of Physics & Astronomy, Hounsfield Road, University of Sheffield, Sheffield S3 7RH, UK
6 Centro de Astrobiología, CSIC-INTA, Ctra. Torrejón a Ajalvir km 4, 28 850 Torrejón de Ardoz, Madrid, Spain
7 Instituto de Astrofísica de Canarias, 38 200 La Laguna, Tenerife, Spain
8 Departamento de Astrofísica, Universidad de La Laguna, 38 205 La Laguna, Tenerife, Spain
9 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21 218, USA
10 Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele ST5 5BG, UK
Received: 16 January 2014
Accepted: 13 February 2014
Context. The commonly used extinction laws of Cardelli et al. (1989, ApJ, 345, 245) have limitations that, among other issues, hamper the determination of the effective temperatures of O and early B stars from optical and near-infrared (NIR) photometry.
Aims. We aim to develop a new family of extinction laws for 30 Doradus, check their general applicability within that region and elsewhere, and apply them to test the feasibility of using optical and NIR photometry to determine the effective temperature of OB stars.
Methods. We use spectroscopy and NIR photometry from the VLT-FLAMES Tarantula Survey and optical photometry from HST/WFC3 of 30 Doradus and we analyze them with the software code CHORIZOS using different assumptions, such as the family of extinction laws.
Results. We derive a new family of optical and NIR extinction laws for 30 Doradus and confirm its applicability to extinguished Galactic O-type systems. We conclude that by using the new extinction laws it is possible to measure the effective temperatures of OB stars with moderate uncertainties and only a small bias, at least up to E(4405−5495) ~ 1.5 mag.
Key words: open clusters and associations: individual: 30 Doradus / dust, extinction / Magellanic Clouds / stars: early-type / stars: fundamental parameters
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© ESO, 2014