The debris disk host star HD 61005: a member of the Argus association?^⋆

¹ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: silvano.desidera@oapd.inaf.it
² INAF – Osservatorio Astronomico di Napoli, Salita Moiariello 16, 80131 Napoli, Italy
³ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
⁴ Universitá di Catania, Dipartimento di Fisica e Astronomia, via S. Sofia 78, 95123 Catania, Italy
⁵ College of Charleston, Department of Physics & Astronomy, USA
⁶ Max Plank Institute for Astronomy, Heidelberg, Germany

Received: 6 December 2010
Accepted: 24 January 2011

Abstract

Context. HD 61005 is a nearby young solar type star that shows a large infrared excess due to a debris disk. The disk has been recently imaged from ground and space, with indications of several components. Some characteristics of the disk suggest the presence of planetary companions around the star, that remain undetected in deep adaptive optics imaging.

Aims. For a better understanding of the system we aim to refine the determination of the stellar parameters, with emphasis on the stellar age and system orientation.

Methods. We used ASAS and Hipparcos photometry and FEROS spectra to determine the rotation period, radial and rotational velocity, chromospheric emission, effective temperature, and chemical composition.

Results. We find no indication of any misalignment between the star rotation axis and the disk. The standard age calibrations applied to several indicators yield an age close to that of the Pleiades (120 Myr); however the kinematic properties strongly support its membership in the younger (40 Myr) Argus association, which also includes the IC 2391 open cluster. Detailed comparison of the properties of HD 61005 and IC 2391 members shows that the characteristics of HD 61005 are compatible with membership to the Argus association, once its rather slow rotation is taken into account, because lithium and other age indicators are somewhat correlated with stellar rotation at a fixed age. We also identify systematic differences between the field and cluster population of the Argus association, which are probably selection effects, so we suggest that additional members with slower rotation and lower activity level are waiting to be identified.