A&A Supplement series, Vol. 127, February I 1997, 423-432

Received April 2; accepted May 23, 1997

Fundamental parameters of the highly reddened young open clusters Westerlund 1 and 2,

A.E. Piatti - E. Bica - J.J. Clariá

Send offprint request: A.E. Piatti, e-mail: andres@oac.uncor.edu

  Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, 5000 Córdoba, Argentina
  Instituto de Fısica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS, Brazil

Abstract:

We study the compact open clusters Westerlund1 (BH197) and Westerlund2. We present CCD integrated spectroscopy for both clusters, and CCD imaging in the V and I bands for the former one. So far, Westerlund1 is possibly the most reddened open cluster studied in detail (). It has an age of 8 3 Myr and a distance from the Sun of  kpc. For Westerlund2 we derive a visual absorption  mag, an age of 2-3 Myr, and  kpc. From luminosity and structural arguments we conclude that Westerlund1, although young and compact, it is a massive cluster, in contrast to Westerlund2.

keywords: open clusters: individual: Westerlund1, Westerlund2 -- open clusters: general

• 1. Introduction
• 2. Observations and reductions
• 3. Imaging of Westerlund 1
• 4. Integrated spectroscopy
• 5. The structure of Westerlund 1
• 6. Concluding remarks
• References