Open AccessDiscovery of five very low mass close binaries, resolved in the visible with lucky imaging ★
Author(s) -
Law N. M.,
Hodgkin S. T.,
Mackay C.D.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10265.x
Subject(s) - physics , brown dwarf , astrophysics , telescope , sky , low mass , stars , mass ratio , binary number , astronomy , binary star , stellar mass , star formation , arithmetic , mathematics
We survey a sample of 32 M5–M8 stars with distance <40 pc for companions with separations between 0.1 and 1.5 arcsec and with Δ m i ≤ 5 . We find five new binaries with separations between 0.15 and 1.1 arcsec, including a candidate brown dwarf companion. The raw binary fraction is 16 +8 −4 per cent and the distance bias corrected fraction is 7 +7 −3 per cent, for companions within the surveyed range. No systems with contrast ratio Δ m i > 1 were found, even though our survey is sensitive to Δ m ≤ 5 (well into the brown dwarf regime). The distribution of orbital radii is in broad agreement with previous results, with most systems at 1–5 au, but one detected binary is very wide at 46.8 ± 5.0 au . We also serendipitously imaged for the first time a companion to Ross 530, a metal‐poor single‐lined spectroscopic binary. We used the new Lucky Imaging system, LuckyCam, on the 2.5‐m Nordic Optical Telescope to complete the 32 very low mass star Sloan Digital Sky Survey (SDSS) i ′ and z ′ survey in only 5 h of telescope time.