A revised moving cluster distance to the Pleiades open cluster^⋆

¹ Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France
e-mail: galli@astro.iag.usp.br
² CNRS, IPAG, 38000 Grenoble, France
³ Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226,  Cidade Universitária, 05508-900, São Paulo – SP, Brazil
⁴ Centro de Astrobiología, INTA-CSIC, PO Box 78, ESAC Campus, 28691 Villanueva de la Cañada, Madrid, Spain
⁵ Dpto. de Inteligencia Artificial, UNED, Juan del Rosal, 16, 28040 Madrid, Spain

Received: 4 July 2016
Accepted: 28 September 2016

Abstract

Context. The distance to the Pleiades open cluster has been extensively debated in the literature over several decades. Although different methods point to a discrepancy in the trigonometric parallaxes produced by the Hipparcos mission, the number of individual stars with known distances is still small compared to the number of cluster members to help solve this problem.

Aims. We provide a new distance estimate for the Pleiades based on the moving cluster method, which will be useful to further discuss the so-called Pleiades distance controversy and compare it with the very precise parallaxes from the Gaia space mission.

Methods. We apply a refurbished implementation of the convergent point search method to an updated census of Pleiades stars to calculate the convergent point position of the cluster from stellar proper motions. Then, we derive individual parallaxes for 64 cluster members using radial velocities compiled from the literature, and approximate parallaxes for another 1146 stars based on the spatial velocity of the cluster. This represents the largest sample of Pleiades stars with individual distances to date.

Results. The parallaxes derived in this work are in good agreement with previous results obtained in different studies (excluding Hipparcos) for individual stars in the cluster. We report a mean parallax of 7.44 ± 0.08 mas and distance of 134.4^+2.9_-2.8 pc that is consistent with the weighted mean of 135.0 ± 0.6 pc obtained from the non-Hipparcos results in the literature.

Conclusions. Our result for the distance to the Pleiades open cluster is not consistent with the Hipparcos catalog, but favors the recent and more precise distance determination of 136.2 ± 1.2 pc obtained from Very Long Baseline Interferometry observations. It is also in good agreement with the mean distance of 133 ± 5 pc obtained from the first trigonometric parallaxes delivered by the Gaia satellite for the brightest cluster members in common with our sample.