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

作者：Chaturvedi Priyanka; Chakraborty Abhijit; Anandarao B G; Roy Arpita; Mahadevan Suvrath

来源：Monthly Notices of the Royal Astronomical Society, 2016, 462(1): 554-564.

DOI：10.1093/mnras/stw1560

• techniques: radial velocities
• binaries: eclipsing
• stars: individual: 1SWASP J234318.41+295556.5
• stars: low-mass

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: T-eff = 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(-0.098)(+0.097) M-circle dot and a radius of 0.854(-0.060)(+0.050) R-circle dot. We combine RV data with SuperWASP photometry to estimate the mass of the secondary, M-B = 0.098 +/- 0.007 M-circle dot, and its radius, R-B = 0.127 +/- 0.007 R-circle dot, with an accuracy of similar to 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.

• 出版日期2016-10-11