EDP Sciences
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Volume 461, Number 2, January II 2007
Page(s) 665 - 668
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20065843

A&A 461, 665-668 (2007)
DOI: 10.1051/0004-6361:20065843

A direct and differential imaging search for sub-stellar companions to $\epsilon$ Indi A

K. Geißler1, 2, S. Kellner1, 3, W. Brandner1, E. Masciadri1, 4, M. Hartung2, T. Henning1, R. Lenzen1, L. Close5, M. Endl6, and M. Kürster1

1  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
    e-mail: kgeissle@eso.org, skellner@keck.hawaii.edu, brandner@mpia.de
2  European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
3  W.M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, Hawaii 96743
4  INAF - Osservatorio Astrofisico di Arecetri, L.go E. Fermi 5, 50125 Firenze, Italy
5  Steward Observatory, University of Arizona, Tucson, Arizona 85721, USA
6  McDonald Observatory, The University of Texas at Austin, Austin, TX 78712-1083, USA

(Received 15 June 2006 / Accepted 27 October 2006)

We have carried out a direct and differential imaging search for sub-stellar companions to $\epsilon$ Indi A using the adaptive optics system NACO at the ESO VLT. The observations were carried out in September 2004 with NACO/SDI as well as with NACO's S27 camera in the H and $K_{\rm s}$ filters. The SDI data cover an area of ~2.8´´ around $\epsilon$ Indi A. No detection was achieved in the inner neighbourhood down to 53 $M_{\rm J}$ (5 $\sigma$ confidence level) at a separation $\geq$0.4´´(1.45 AU) and down to 21 $M_{\rm J}$ for separations $\ge$1.3´´ (4.7 AU). To cover a wider field of view, observations with the S27 camera and a coronagraphic mask were obtained. We detected a faint source at a separation of (7.3 $\pm$ 0.1)´´and a position angle of $(302.9\,\pm\,0.8)^{\circ}$. The photometry for the candidate companion yields $m_{\rm H}$ = (16.45 $\pm$ 0.04) mag and $ m_{K_{\rm s}}$ = (15.41 $\pm$ 0.06) mag, respectively. Those magnitudes and the resulting color ( $H-K_{\rm s}$) = (1.04 $\pm$ 0.07) mag fit best to a spectral type of L5 - L9.5 if it is bound. Observations done with HST/NICMOS by M. Endl have shown the source to be a background object.

Key words: stars: low-mass, brown dwarfs -- stars: fundamental parameters

© ESO 2006