M35
Messier 35 or M35, also known as NGC 2168, is an open cluster of stars in the northern constellation of Gemini. It was discovered by Philippe Loys de Chéseaux around 1745 and independently discovered by John Bevis before 1750. The cluster is scattered over an area of the sky almost the size of the full moon and is located 3,870 light-years (1,186 parsecs) from Earth. The compact open cluster NGC 2158 lies directly southwest of M35.
Leonard & Merritt (1989) computed the mass of M35 using a statistical technique based on proper motion velocities of its stars. The mass within the central 3.75 parsecs was found to be between 1600 and 3200 solar masses (95 percent confidence), consistent with the mass of a realistic stellar population within the same radius. Bouy et al. (2015) found a mass of around 1,600 M☉ within the central 27.5′ × 27.5′. There are 305 candidate members with a probability of 95% or higher, and up to 4,349 with a 50% membership probability. The cluster metallicity is given by [Fe/H] = −0.21±0.10.
Of 418 probable cluster members, Leiner et al. (2015) found 64 that have variable radial velocities and thus are binary star systems. Four probable cluster members are chemically peculiar stars, while HD 41995, which lies within the cluster area, shows emission lines. Hu et al. (2005) found 13 variable stars in the cluster field, although at least three are suspect as cluster members.
