A direct and differential imaging search for sub-stellar companions to ϵ Indi A

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

Abstract

We have carried out a direct and differential imaging search for sub-stellar companions to ϵ 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_s filters. The SDI data cover an area of ~2.8´´ around ϵ Indi A. No detection was achieved in the inner neighbourhood down to 53 M_J (5 σ confidence level) at a separation ≥0.4´´(1.45 AU) and down to 21 M_J for separations ≥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 ± 0.1)´´and a position angle of . The photometry for the candidate companion yields m_H = (16.45 ± 0.04) mag and = (15.41 ± 0.06) mag, respectively. Those magnitudes and the resulting color () = (1.04 ± 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.