BD -22 5866: A low-mass, quadruple-lined spectroscopic and eclipsing binary

Evgenya Shkolnik, Michael C. Liu, I. Neill Reid, Leslie Hebb, Andrew C. Cameron, Carlos A. Torres, David M. Wilson

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We report our discovery of an extremely rare, low-mass, quadruple-lined spectroscopic binary BD -22 5866 (=NLTT 53279, integrated spectral type = M0 V), found during an ongoing search for the youngest M dwarfs in the solar neighborhood. From the cross-correlation function, we are able to measure relative flux levels, estimate the spectral types of the components, and set upper limits on the orbital periods and separations. The resulting system is hierarchical, composed of a K7 + K7 binary and an M1 + M2 binary with semimajor axes of aA sin iA ≤ 0.06 and aB sin i B ≤ 0.30 AU. A subsequent search of the SuperWASP photometric database revealed that the K7 + K7 binary is eclipsing with a period of 2.21 days and at an inclination angle of 85°. Within uncertainties of 5%, the masses and radii of both components appear to be equal (0.59 M, 0.61 R). These two tightly orbiting stars (a = 0.035 AU) are in synchronous rotation, causing the observed excess Ca II, Hα, X-ray, and UVemission. The fact that the system was unresolved with published adaptive optics imaging, limits the projected physical separation of the two binaries at the time of the observation to dAB ≲4.1 AU at the photometric distance of 51 pc. The maximum observed radial velocity difference between the A and B binaries limits the orbit to aAB sin iAB ≤ 6.1 AU. As this tight configuration is difficult to reproduce with current formation models of multiple systems, we speculate that an early dynamical process reduced the size of the system, such as the interaction of the two binaries with a circumquadruple disk. Intensive photometric, spectroscopic, and interferometric monitoring, as well as a parallax measurement of this rare quadruple system, is certainly warranted.

Original languageEnglish (US)
Pages (from-to)1248-1255
Number of pages8
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 1 2008
Externally publishedYes


  • Binaries: eclipsing
  • Binaries: spectroscopic
  • Stars: activity
  • Stars: individual (BD -22 5866)
  • Stars: late-type
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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