Detection of a very low mass star in an eclipsing binary system

Priyanka Chaturvedi, Abhijit Chakraborty, B. G. Anandarao, Arpita Roy, Suvrath Mahadevan

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10 Scopus citations


We report the detection of a very low mass star (VLMS) companion to the primary star 1SWASP J234318.41+295556.5A (J2343+29A), using radial velocity (RV) measurements from the PARAS (PRL Advanced Radial-velocity Abu-sky Search) high-resolution echelle spectrograph. The periodicity of the single-lined eclipsing binary (SB1) system, as determined from 20 sets of RV observations from PARAS and 6 supporting sets of observations from SOPHIE data, is found to be 16.953 d as against the 4.24 d period reported from Super-WASP photometry. It is likely that inadequate phase coverage of the transit with SuperWASP photometry led to the incorrect determination of the period for this system. We derive the spectral properties of the primary star from the observed stellar spectra: Teff = 5125 ± 67 K, [Fe/H] = 0.1 ± 0.14 and logg = 4.6 ± 0.14, indicating a K1V primary. Applying the Torres relation to the derived stellar parameters, we estimate a primary mass 0.864+0.097 -0.098 M and a radius of 0.854+0.050 -0.060 R. We combine RV data with SuperWASP photometry to estimate the mass of the secondary, MB = 0.098 ± 0.007M⊙, and its radius, RB = 0.127 ± 0.007 R, with an accuracy of ~7 per cent. Although the observed radius is found to be consistent with the Baraffe's theoretical models, the uncertainties on the mass and radius of the secondary reported here are model dependent and should be used with discretion. Here, we establish this system as a potential benchmark for the study of VLMS objects, worthy of both photometric follow-up and the investment of time on high-resolution spectrographs paired with large-aperture telescopes.

Original languageEnglish (US)
Pages (from-to)554-564
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Oct 11 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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