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arXiv · astro-ph/0611584

WIYN Open Cluster Study. XXVI. Improved kinematic membership and spectroscopy of IC 2391

I. Platais·C. Melo·J. -C. Mermilliod·V. Kozhurina-Platais·J. P. Fulbright·R. A. Mendez·M. Altmann·J. Sperauskas
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Abstract

[Abridged] Contex. Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution. The young and nearby open cluster IC 2391 is well-suited to studies of these two evolutionary phases. Aims. We establish a bona fide set of cluster members and then analyze this set in terms of binary frequency, projected rotational velocities, [Fe/H], and lithium abundance. In the wake of the Hipparcos distance controversy for the Pleiades, we compare the main-sequence fitting distance modulus to the Hipparcos mean parallax for IC 2391. Results. The proper-motion survey covers a 6 times larger sky area than the prior targeted searches for cluster members in IC 2391. A total of 66 stars are considered bona fide cluster members down to a mass equivalent to 0.5M_sun. A quarter of them have been newly identified with many in the F2-K5 spectral range, which is crucial for a main-sequence fit. We find a mean [Fe/H] value of +0.06+/-0.06, when a solar abundance of log epsilon (Fe)=7.45 is adopted. The main sequence fitting yields a distance modulus that is 0.19 mag larger than that derived from Hipparcos parallaxes; thus this offset nearly has the size of a similar offset found for the Pleiades. The Li abundance pattern is similar to the earlier findings and is typical for a 40 Myr old open cluster.

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I. Platais, C. Melo, J. -C. Mermilliod, V. Kozhurina-Platais, J. P. Fulbright, R. A. Mendez, M. Altmann, J. Sperauskas. 2006-11-17. WIYN Open Cluster Study. XXVI. Improved kinematic membership and spectroscopy of IC 2391. https://doi.org/10.1051/0004-6361%3A20065756

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