KELT-10b: the first transiting exoplanet from the KELT-South survey – a hot sub-Jupiter transiting a V= 10.7 early G-star

We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright V = 10.7 star (TYC 8378-64-1), with T_(eff) = 5948 ± 74 K, log g = 4.319^(+0.020)_(−0.030) and [Fe/H] = 0.09^(+0.11)_(−0.10), an inferred mass M^* = 1.112^(+0.055)_(−0.061) M_⊙ and radius R^* = 1.209^(+0.047)_(−0.035) R_⊙. The planet has a radius Rp = 1.399^(+0.069)_(−0.049) RJ and mass Mp = 0.679^(+0.039)_(−0.038) MJ. The planet has an eccentricity consistent with zero and a semimajor axis a = 0.05250^(+0.00086)_(−0.00097) au. The best-fitting linear ephemeris is T_0 = 2457 066.720 45 ± 0.000 27 BJD_(TDB) and P = 4.166 2739 ± 0.000 0063 d. This planet joins a group of highly inflated transiting exoplanets with a larger radius and smaller mass than that of Jupiter. The planet, which boasts deep transits of 1.4 per cent, has a relatively high equilibrium temperature of T_(eq) = 1377^(+28)_(−23) K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of 0.817^(+0.068)_(−0.054) × 10^9 erg s^(−1) cm^(−2), which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b may not survive beyond the current subgiant phase, depending on the rate of in-spiral of the planet over the next few Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V < 11 in the Southern hemisphere, making it a promising candidate for future atmospheric characterization studies

KELT-10b: the first transiting exoplanet from the KELT-South survey – a hot sub-Jupiter transiting a V= 10.7 early G-star

We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright V = 10.7 star (TYC 8378-64-1), with T_(eff) = 5948 ± 74 K, log g = 4.319^(+0.020)_(−0.030) and [Fe/H] = 0.09^(+0.11)_(−0.10), an inferred mass M^* = 1.112^(+0.055)_(−0.061) M_⊙ and radius R^* = 1.209^(+0.047)_(−0.035) R_⊙. The planet has a radius Rp = 1.399^(+0.069)_(−0.049) RJ and mass Mp = 0.679^(+0.039)_(−0.038) MJ. The planet has an eccentricity consistent with zero and a semimajor axis a = 0.05250^(+0.00086)_(−0.00097) au. The best-fitting linear ephemeris is T_0 = 2457 066.720 45 ± 0.000 27 BJD_(TDB) and P = 4.166 2739 ± 0.000 0063 d. This planet joins a group of highly inflated transiting exoplanets with a larger radius and smaller mass than that of Jupiter. The planet, which boasts deep transits of 1.4 per cent, has a relatively high equilibrium temperature of T_(eq) = 1377^(+28)_(−23) K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of 0.817^(+0.068)_(−0.054) × 10^9 erg s^(−1) cm^(−2), which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b may not survive beyond the current subgiant phase, depending on the rate of in-spiral of the planet over the next few Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V < 11 in the Southern hemisphere, making it a promising candidate for future atmospheric characterization studies

The KELT-South Telescope

The Kilodegree Extremely Little Telescope (KELT) project is a survey for new transiting planets around bright stars. KELT-South is a small-aperture, wide-field automated telescope located at Sutherland, South Africa. The telescope surveys a set of 26 degree by 26 degree fields around the southern sky, and targets stars in the range of 8 < V < 10 mag, searching for transits by Hot Jupiters. This paper describes the KELT-South system hardware and software and discusses the quality of the observations. We show that KELT-South is able to achieve the necessary photometric precision to detect transits of Hot Jupiters around solar-type main-sequence stars.Comment: 26 pages, 13 figure

The Architecture of the GW Ori Young Triple Star System and Its Disk: Dynamical Masses, Mutual Inclinations, and Recurrent Eclipses

We present spatially and spectrally resolved Atacama Large Millimeter/submillimeter Array (ALMA) observations of gas and dust orbiting the pre-main sequence hierarchical triple star system GW Ori. A forward-modeling of the ${}^{13}$CO and C${}^{18}$O $J$=2-1 transitions permits a measurement of the total stellar mass in this system, $5.29 \pm 0.09\,M_\odot$, and the circum-triple disk inclination, $137.6 \pm 2.0^\circ$. Optical spectra spanning a 35 year period were used to derive new radial velocities and, coupled with a spectroscopic disentangling technique, revealed that the A and B components of GW Ori form a double-lined spectroscopic binary with a $241.50\pm0.05$ day period; a tertiary companion orbits that inner pair with a $4218\pm50$ day period. Combining the results from the ALMA data and the optical spectra with three epochs of astrometry in the literature, we constrain the individual stellar masses in the system ($M_\mathrm{A} \approx 2.7\,M_\odot$, $M_\mathrm{B} \approx 1.7\,M_\odot$, $M_\mathrm{C} \approx 0.9\,M_\odot$) and find strong evidence that at least one (and likely both) stellar orbital planes are misaligned with the disk plane by as much as $45^\circ$. A $V$-band light curve spanning 30 years reveals several new $\sim$30 day eclipse events 0.1-0.7~mag in depth and a 0.2 mag sinusoidal oscillation that is clearly phased with the AB-C orbital period. Taken together, these features suggest that the A-B pair may be partially obscured by material in the inner disk as the pair approaches apoastron in the hierarchical orbit. Lastly, we conclude that stellar evolutionary models are consistent with our measurements of the masses and basic photospheric properties if the GW Ori system is $\sim$1 Myr old.Comment: 26 pages, 15 figures, accepted to Ap

Long-period High-amplitude Red Variables in the KELT Survey

We present a sample of 4132 Mira-like variables (red variables with long periods and high amplitudes) in the Kilodegree Extremely Little Telescope (KELT) survey. Of these, 376 are new Mira-like detections. We used Two Micron All Sky Survey (2MASS) colors to identify candidate asymptotic giant branch stars. We searched for photometric variability among the candidate asymptotic giant branch stars and identified stars that show periodic variability. We selected variables with high amplitudes and strong periodic behavior using a Random Forest classifier. Of the sample of 4132 Mira-like variables, we estimate that 70% are Miras and 30% are semiregular (SR) variables. We also adopt the method of using (W_(RP) - W_(K)) versus (J - K_s) colors in distinguishing between O-rich and C-rich Miras and find it to be an improvement over 2MASS colors