Università di Padova, Dept. di Astronomia, Vicolo dell'Osservatorio 2, 35122 Padova, Italy e-mail: firstname.lastname@example.org
2 Universidade Federal do Rio Grande do Sul, Dept. de Astronomia, CP 15051, Porto Alegre 91500-970, Brazil e-mail: email@example.com
3 Universidade de São Paulo, CP 3386, São Paulo 01060-970, Brazil e-mail: firstname.lastname@example.org
Corresponding author: B. Barbuy, email@example.com
Accepted: 7 May 2002
Pismis 23 and Stephenson 2 are two very reddened open clusters, projected close to the Galactic plane. We present VI and JH photometry for Pismis 23 and I and Gunn z for Stephenson 2. We derive a relatively old age of ~700 Myr for Pismis 23, with a reddening value of and a distance kpc from the Sun. Stephenson 2 has a clump of red supergiants, indicating a young age of about 20 Myr, somewhat younger and more distant ( kpc) than recently reported in the literature. The age estimate for such a young object is crucial for the distance estimate. The high reddening of these two clusters relative to predictions from the diffuse interstellar medium at their distances is due to discrete intervening clouds.
Key words: open clusters and associations: individual: Pismis 23, Stephenson 2 / stars: Hertzsprung-Russell (HR) and C-M diagrams
© ESO, 2002