The M-dwarfs in Multiples (MinMs) survey – I. Stellar multiplicity among low-mass stars within 15 pc★

Abstract

We present a large-scale, volume-limited companion survey of 245 late-K to\nmid-M (K7-M6) dwarfs within 15 pc. Infrared adaptive optics (AO) data were\nanalysed from the Very Large Telescope, Subaru Telescope, Canada-France-Hawaii\nTelescope, and MMT Observatory to detect close companions to the sample from\n$\\sim$1 au to 100 au, while digitised wide-field archival plates were searched\nfor wide companions from $\\sim$100 au to 10,000 au. With sensitivity to the\nbottom of the main sequence over a separation range of 3 au to 10,000 au,\nmultiple AO and wide-field epochs allow us to confirm candidates with common\nproper motions, minimize background contamination, and enable a measurement of\ncomprehensive binary statistics. We detected 65 co-moving stellar companions\nand find a companion star fraction of $23.5 \\pm 3.2$ per cent over the 3 au to\n10,000 au separation range. The companion separation distribution is observed\nto rise to a higher frequency at smaller separations, peaking at closer\nseparations than measured for more massive primaries. The mass ratio\ndistribution across the $q = 0.2 - 1.0$ range is flat, similar to that of\nmultiple systems with solar-type primaries. The characterisation of binary and\nmultiple star frequency for low-mass field stars can provide crucial\ncomparisons with star forming environments and hold implications for the\nfrequency and evolutionary histories of their associated disks and planets.\n