Transit timing variation analysis of the low-mass brown dwarf KELT-1 b

Abstract: We investigate whether there is a variation in the orbital period of the short-period brown dwarf-mass KELT-1\,b, which is one of the best candidates to observe orbital decay. We obtain 19 high-precision transit light curves of the target using six different telescopes. We add all precise and complete transit light curves from open databases and the literature, as well as the available TESS observations from sectors 17 and 57, to form a transit timing variation (TTV) diagram spanning more than 10 years of observations. The analysis of the TTV diagram, however, is inconclusive in terms of a secular or periodic variation, hinting that the system might have synchronized. We update the transit ephemeris and determine an informative lower limit for the reduced tidal quality parameter of its host star of Q$_{\star}^{\prime} > (8.5 \pm 3.9) \times 10^{6}$ assuming that the stellar rotation is not yet synchronised. Using our new photometric observations, published light curves, the TESS data, archival radial velocities and broadband magnitudes, we also update the measured parameters of the system. Our results are in good agreement with those found in previous analyses.