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

Abstract

We have carried out a direct and differential imaging search for sub-stellar companions to ɛ 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 ɛ 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 (302.9 ± 0.8)°. The photometry for the candidate companion yields m_H = (16.45 ± 0.04) mag and m_{K_s} = (15.41 ± 0.06) mag, respectively. Those magnitudes and the resulting color (H-K_s) = (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.