The blue to red supergiant ratio in young clusters at various metallicities

P. Eggenberger; G. Meynet; A. Maeder

doi:10.1051/0004-6361:20020262

paper

The blue to red supergiant ratio in young clusters at various metallicities

arXiv:astro-ph/0202478 · doi:10.1051/0004-6361:20020262

Abstract

We present new determinations of the blue to red supergiant ratio ( $B / R$ ) in young open clusters at various metallicities. For this purpose, we examine the HR diagrams of 45 clusters in the Galaxy and of 4 clusters in the Magellanic Clouds. The identification of supergiants is based on spectroscopic measurements (with photometric counts to check the results). The new counts confirm the increase of the $B / R$ ratio when the metallicity increases with the following normalized relation : $\frac{B / R}{( B / R ) _{⊙}} ≅ 0.05 \cdot e^{3 \frac{Z}{Z _{⊙}}}$ , where $Z_{⊙} = 0.02$ and $(B / R)_{⊙}$ is the value of $B / R$ at $Z_{⊙}$ which depends on the definition of $B$ and $R$ and on the age interval considered (e.g. for spectroscopic counts including clusters with $lo g a g e$ between 6.8 and 7.5, $(B / R)_{⊙} ≅ 3$ when $B$ includes O, B and A supergiants).

7 pages, 2 figures. accepted for publication in A&A

References in corpus (1)

Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC

The blue to red supergiant ratio in young clusters at various metallicities

Abstract

References in corpus (1)

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