We report the detection of a very low mass star ( VLMS ) companion to the primary star 1SWASPJ234318.41 + 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 ( SB _ { 1 } ) 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 SuperWasp 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 ~ { } \pm~ { } 67 K , [ Fe / H ] = 0.1 ~ { } \pm~ { } 0.14 and { log } ~ { } g = 4.6 ~ { } \pm~ { } 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 _ { \odot } and a radius of 0.854 _ { -0.060 } ^ { +0.050 } R _ { \odot } .
We combine RV data with SuperWASP photometry to estimate the mass of the secondary , M _ { B } = 0.098 \pm 0.007 M _ { \sun } , and its radius , R _ { B } = 0.127 \pm 0.007 ~ { } R _ { \sun } , with an accuracy of \sim 7 \% .
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 .