1997/08/15 by D. Raboud, Raboud, D., J. -C. Mermilliod +2
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9708144
15 pages, 11 figures. To be published in Astronomy and Astrophysics Main Journal
arxiv created 1997/08/15 · openalex publication_date 1997/08/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
On the basis of the best available member list and duplicity information, we have studied the radial distribution of 270 stars and multiple systems earlier than K0 in the Pleiades. Five new long period spectroscopic binaries have been identified from the CORAVEL observations. We have found a clear mass segregation between binaries and single stars, which is explained by the greater average mass of the multiple systems. The mass function of the single stars and primaries appears to be significantly different. While the central part of the cluster is spherical, the outer part is clearly elliptical, with an ellipticity of 0.17. The various parameters describing the Pleiades are (for a distance of 125 pc): core radius rc=0.6 deg (1.4 pc), tidal radius rt=7.4 deg (16 pc), half mass radius rm/2=0.88 deg (1.9 pc), harmonic radius r=1.82 deg (4 pc). Low-mass stars (later than K0) probably extend further out and new proper motion and radial velocity surveys over a larger area and to fainter magnitudes would be very important to improve the description of the cluster structure and complete mass function.