Abstract. We present the first results from our search for close stellar and sub-stellar companions to young nearby stars on the northern sky. Our infrared imaging observations are obtained with the 3.5 m Calar Alto telescope and the AO system ALFA. With two epoch observations which were separated by about one year, we found two co-moving companion candidates, one close to HD77407 and one close to GJ577. For the companion candidate near GJ577, we obtained an optical spectrum showing spectral type M4.5; this candidate is a bound low-mass stellar companion confirmed by both proper motion and spectroscopy. We estimate the masses for HD 77407 B and GJ 577 B to be ∼ 0.3 to 0.5 M ⊙ and ∼ 0.16 to 0.2 M⊙, respectively. Compared to Siess al. (2000) models, each of the two pairs appears co-eval with HD77407 A,B being 10 to 40Myrs and GJ 577 A,B being ≥ 100 Myrs old. We also took multi-epoch high-resolution spectra of HD77407 to search for sub-stellar companions, but did not find any with 3 MJup as upper mass (msin i) limit (for up to 4 year orbits); however, we detected a long-term radial velocity trend in HD77407 A, consistent with a ∼ 0.3 M ⊙ companion at ∼ 50AU separation, i.e. the one detecte
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