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

A direct and differential imaging search for sub-stellar companions to ǫ Indi A Abstract. We have carried out a direct and differential imaging search for sub-stellar companions to ǫ 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 Ks filters. The SDI data cover an area of ∼ 2.8 ′′ around ǫ Indi A. No detection was achieved in the inner neighbourhood down to 53 MJ (5 σ confidence level) at a separation ≥ 0.4 ′′ (1.45 AU) and down to 21 MJ 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 mH = (16.45 ± 0.04) mag and mK s = (15.41 ± 0.06) mag, respectively. Those magnitudes and the resulting color (H-Ks) = (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.