The ionizing cluster of 30 Doradus. I. Internal reddening from NTT photometry and multi-object spectroscopy
Abstract
UBV profile fitting photometry is presented for 1469 stars within 90arcsec of the center of the ionizing cluster of 30 Doradus (NGC 2070). A value of 0.82 +/- 0.03 is found for the extinction parameter S = E(U-B)/E(B-V), constant over almost the whole area covered by this research, with some evidence for local variations. Two reddening components can be identified: a smooth and moderate one that increases towards R136, and a clumpy one varying widely across the face of the cluster. The total-to-selective extinction parameter, R_V = A_V/E(B-V), is found to be in the range of 3.0 to 3.7, consistent with previous determinations. A new visualization tool, the colour-magnitude stereogram, is introduced and used to argue that: (1) the observations imply mass segregation in a dust filled cluster; (2) that there has been continuous dust formation near the cluster core up to the present; and (3) that an insidious systematic error has plagued previous determinations of IMF slopes. A method to obtain an unbiased estimate of the slope is discussed. Based on observations collected with the NTT ESO telescope. Table~2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1999
- Bibcode:
- 1999A&A...341...98S
- Keywords:
-
- STARS: EARLY-TYPE;
- STARS: LUMINOSITY FUNCTION;
- MASS FUNCTION;
- ISM: DUST;
- EXTINCTION;
- GALAXY: OPEN CLUSTERS AND ASSOCIATIONS: GENERAL;
- GALAXIES: MAGELLANIC CLOUDS