J/A+A/341/98 J/A+A/341/98 The ionizing cluster of 30 Doradus. I. F Selman J Melnick G Bosch R Terlevich Astron. Astrophys. 341 98 1999 1999A&A...341...98S II/187 : 30 Doradus OB Associations (Parker 1992) J/AJ/107/1054 : 30 Dor region UBV photometry (Malumuth+, 1994) J/ApJ/413/604 : 30 Dor UV and optical photometry (Hill+, 1993) Clusters, open Photometry, UBV dust, extinction Magellanic Clouds open clusters and associations: general stars: early-type stars: luminosity function, mass function 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.

RMC 136HD 3826830 Dor05 38 42.8-69 06 03 NGC 207005 38 42.-69 05 30

Seq Star number --- xpos X coordinate x is oriented East to West (- --> +) Position of R136: 456.4 (RA=05 38 42.8, DE=-69 06 03 (J2000)) Scale: 0.13 arcsec/pix pix ypos Y coordinate y is oriented South to North (- --> +) Position of R136: 432.3 (RA=05 38 42.8, DE=-69 06 03 (J2000)) Scale: 0.13 arcsec/pix pix P93 Id in Parker's catalogue A -1 in this column indicates no match with the catalogue of Parker (1993AJ....106..560P, Cat. <II/187>). A negative Parker number (smaller than -1) indicates that the star has spectroscopy. --- Vmag Apparent V magnitude mag e_Vmag Error in apparent V magnitude mag Bmag Apparent B magnitude mag e_Bmag Error in apparent B magnitude mag Umag Apparent U magnitude mag e_Umag Error in apparent U magnitude mag Chi2 Chi**2 parameter from IRAF/DAOPHOT II --- Fernando J. Selman ESO Patricia Bauer CDS 1998Dec18Fernando J. Selman <fselman@sc6.sc.eso.org> J_A+A_341_98.xml