We report on the discovery of HAT-P-12b, a transiting extrasolar planet orbiting the moderately bright V~12.8 K4 dwarf GSC 03033-00706, with a period P=3.2130598+/-0.0000021d, transit epoch T_c_=2454419.19556+/-0.00020 (BJD), and transit duration 0.0974+/-0.0006d. The host star has a mass of 0.73+/-0.02M_{sun}_, radius of 0.70^+0.02^_-0.01_R_{sun}_, effective temperature 4650+/-60K, and metallicity [Fe/H]=-0.29+/-0.05. We find a slight correlation between the observed spectral line bisector spans and the radial velocity, so we consider, and rule out, various blend configurations including a blend with a background eclipsing binary, and hierarchical triple systems where the eclipsing body is a star or a planet. We conclude that a model consisting of a single star with a transiting planet best fits the observations, and show that a likely explanation for the apparent correlation is contamination from scattered moonlight. Based on this model, the planetary companion has a mass of 0.211+/-0.012M_J_ and radius of 0.959^+0.029^_-0.021_R_J_ yielding a mean density of 0.295+/-0.025g/cm^3^. Comparing these observations with recent theoretical models, we find that HAT-P-12b is consistent with a ~1-4.5Gyr, mildly irradiated, H/He-dominated planet with a core mass M_C_<~10M_{earth}_.
We report on the discovery of a planetary system with a close-in transiting hot Jupiter on a near circular orbit and a massive outer planet on a highly eccentric orbit. The inner planet, HAT-P-13b, transits the bright V=10.622 G4 dwarf star GSC 3416-00543 every P=2.916260+/-0.000010 days, with transit epoch T_c_=2454779.92979+/-0.00038 (BJD) and duration 0.1345+/-0.0017 days. The outer planet HAT-P-13c orbits the star every P_2_=428.5+/-3.0 days with a nominal transit center (assuming zero impact parameter) of T_2c_=2454870.4+/-1.8 (BJD) or time of periastron passage T_2,peri_=2454890.05+/-0.48 (BJD). Transits of the outer planet have not been observed, and may not be present. The host star has a mass of 1.22^+0.05^_-0.10_M_{sun}_, radius of 1.56+/-0.08R_{sun}_, effective temperature of 5653+/-90K, and is rather metal-rich with [Fe/H]=+0.41+/-0.08.
We report the discovery of HAT-P-17b,c, a multi-planet system with an inner transiting planet in a short-period, eccentric orbit and an outer planet in a 4.4 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright V=10.54 early K dwarf star GSC 2717-00417, with an orbital period P=10.338523+/-0.000009 days, orbital eccentricity e=0.342+/-0.006, transit epoch T_c_=2454801.16943+/-0.00020 (BJD: barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1690+/-0.0009 days. HAT-P-17b has a mass of 0.534+/-0.018M_J_ and radius of 1.010+/-0.029R_J_ yielding a mean density of 0.64+/-0.05g/cm3. This planet has a relatively low equilibrium temperature in the range 780-927K, making it an attractive target for follow-up spectroscopic studies. The outer planet, HAT-P-17c, has a significantly longer orbital period P_2_=1610+/-20d and a minimum mass m_2_sini_2_=1.31^+0.18^_-0.15_M_J_. The orbital inclination of HAT-P-17c is unknown as transits have not been observed and may not be present. The host star has a mass of 0.86+/-0.04M_{sun}_, radius of 0.84+/-0.02R_{sun}_, effective temperature 5246+/-80K, and metallicity [Fe/H]=0.00+/-0.08. HAT-P-17 is the second multi-planet system detected from ground-based transit surveys.
We study the most precise light curves of the planet-host HAT-P-36 that we obtained from the ground primarily with a brand-new 80cm telescope (T80) very recently installed at Ankara University Kreiken Observatory (AUKR) of Turkey and also from the space with Transiting Exoplanet Survey Satellite (TESS). The main objective of the study is to analyze the Transit Timing Variations (TTV) observed in the hot-Jupiter type planet HAT-P-36 b, a strong candidate for orbital decay, based on our own observations as well as that have been acquired by professional and amateur observers since its discovery (Bakos et al., 2012AJ....144...19B, Cat. J/AJ/144/19). HAT-P-36 displays out-of-transit variability as well as light curve anomalies during the transits of its planet due to stellar spots. We collected and detrended all the complete transit light curves we had access to from these anomalies, which we modeled with EXOFAST (Eastman et al., 2013PASP..125...83E) and measured the mid-transit times forming a homogeneous data set for a TTV analysis. We found an increase in the orbital period of HAT-P-36 b at a rate of 0.014 seconds per year from the best fitting quadratic function, which is only found in the TTV constructed by making use of the mid-transit times measured from detrended light curves, against an expectation of an orbital decay based on its parameters. We refined the values of these system parameters by modelling the Spectral Energy Distribution of the host star, its archival radial velocity observations from multiple instruments, and most precise transit light curves from the space and the ground covering a wide range of wavelengths with EXOFASTv2 (Eastman, 2017, ascl, 1710, 003). We also analyzed the out-of-transit variability from TESS observations to search for potential rotational modulations through a frequency analysis. We report a statistically significant periodicity in the TESS light curve at 4.22+/-0.02 days, which might have been caused by instrumental systematics but should be tracked in the future observations of the target.
We report the discovery of HATS-13b and HATS-14b, two hot-Jupiter transiting planets discovered by the HATSouth survey. The host stars are quite similar to each other (HATS-13: V=13.9 mag, M*=0.96M_{sun}_, R*=0.89R_{sun}_, Teff=5500K, [Fe/H]=0.05; HATS-14: V=13.8mag, M*=0.97M_{sun}_, R*=0.93R_{sun}_, Teff=5350K, [Fe/H]=0.33) and both the planets orbit around them with a period of roughly 3 days and a separation of roughly 0.04 au. However, even though they are irradiated in a similar way, the physical characteristics of the two planets are very different. HATS-13b, with a mass of Mp=0.543M_Jup_ and a radius of Rp=1.212R_Jup_, appears as an inflated planet, while HATS-14b, having a mass of Mp=1.071M_Jup_ and a radius of Rp=1.039R_Jup_, is only slightly larger in radius than Jupiter.
We report the discovery of four transiting hot Jupiters from the HATSouth survey: HATS-39b, HATS-40b, HATS-41b, and HATS-42b. These discoveries add to the growing number of transiting planets orbiting moderately bright (12.5<=V<=13.7) F dwarf stars on short (2-5d) periods. The planets have similar radii, ranging from 1.33^+0.29^_-0.20_R_J_ for HATS-41b to 1.58^+0.16^_-0.12_R_J_ for HATS-40b. Their masses and bulk densities, however, span more than an order of magnitude. HATS-39b has a mass of 0.63+/-0.13M_J_, and an inflated radius of 1.57+/-0.12R_J_, making it a good target for future transmission spectroscopic studies. HATS-41b is a very massive 9.7+/-1.6M_J_ planet and one of only a few hot Jupiters found to date with a mass over 5M_J_. This planet orbits the highest metallicity star ([Fe/H]=0.470+/-0.010) known to host a transiting planet and is also likely on an eccentric orbit. The high mass, coupled with a relatively young age (1.34^+0.31^_-0.51_Gyr) for the host star, is a factor that may explain why this planet's orbit has not yet circularized.
We report the discovery of HATS-2b, the second transiting extrasolar planet detected by the HATSouth survey. HATS- 2b is moving on a circular orbit around a V=13.6mag, K-type dwarf star (GSC 6665-00236), at a separation of 0.0230+/-0.0003AU and with a period of 1.3541-days. The planetary parameters have been robustly determined using a simultaneous t of the HATSouth, MPG/ESO 2.2m/GROND, Faulkes Telescope South/Spectral transit photometry, and MPG/ESO 2.2m/FEROS, Euler 1.2m/CORALIE, AAT 3.9m/CYCLOPS radial-velocity measurements.
We report on the result of a campaign to monitor 25 HATSouth candidates using the Kepler space telescope during Campaign 7 of the K2 mission. We discover HATS-36b (EPIC 215969174b, K2-145b), an eccentric (e=0.105+/-0.028) hot Jupiter with a mass of 3.216+/-0.062 M_J_ and a radius of 1.235+/-0.043 R_J_, which transits a solar-type G0V star (V=14.386) in a 4.1752-day period. We also refine the properties of three previously discovered HATSouth transiting planets (HATS-9b, HATS-11b, and HATS-12b) and search the K2 data for TTVs and additional transiting planets in these systems. In addition, we also report on a further three systems that remain as Jupiter-radius transiting exoplanet candidates. These candidates do not have determined masses, however pass all of our other vetting observations. Finally, we report on the 18 candidates that we are now able to classify as eclipsing binary or blended eclipsing binary systems based on a combination of the HATSouth data, the K2 data, and follow-up ground-based photometry and spectroscopy. These range in periods from 0.7 day to 16.7 days, and down to 1.5 mmag in eclipse depths. Our results show the power of combining ground-based imaging and spectroscopy with higher precision space-based photometry, and serve as an illustration as to what will be possible when combining ground-based observations with TESS data.
We report the discovery by the HATNet survey of HAT-TR-318-007, a P=3.34395390+/-0.00000020 day period detached double-lined M dwarf binary with total secondary eclipses. We combine radial velocity (RV) measurements from TRES/FLWO 1.5 m and time-series photometry from HATNet, FLWO 1.2 m, BOS 0.8 m, and NASA K2 Campaign 5, to determine the masses and radii of the component stars: M_A_=0.448+/-0.011 M_{sun}_^N^, M_B_=0.2721_-0.0042_^+0.0041^ M_{sun}_^N^, R_A_=0.4548_-0.0036_^+0.0035^ R_{sun}_^N^, and R_B_=0.2913_-0.0024_^+0.0023^ R_{sun}_^N^. We obtained a FIRE/Magellan near-infrared spectrum of the primary star during a total secondary eclipse, and we use this to obtain disentangled spectra of both components. We determine spectral types of ST_A_=M3.71+/-0.69 and ST_B_=M5.01+/-0.73 and effective temperatures of T_eff,A_=3190+/-110 K and T_eff,B_=3100+/-110 K for the primary and secondary star, respectively. We also measure a metallicity of [Fe/H]=+0.298+/-0.080 for the system. We find that the system has a small, but significant, nonzero eccentricity of 0.0136+/-0.0026. The K2 light curve shows a coherent variation at a period of 3.41315_-0.00032_^+0.00030^ days, which is slightly longer than the orbital period, and which we demonstrate comes from the primary star. We interpret this as the rotation period of the primary. We perform a quantitative comparison between the Dartmouth stellar evolution models and the seven systems, including HAT-TR-318-007, that contain M dwarfs with 0.2 M_{sun}_^N^<M<0.5 M_{sun}_^N^, have metallicity measurements, and have masses and radii determined to better than 5% precision. Discrepancies between the predicted and observed masses and radii are found for three of the systems.
A deep CCD UBVRI photometric survey combined with UBVRI polarimetric observations of 21 bright stars was carried out in the region of the open cluster Havlen-Moffat No. 1. Our data reveal that the extinction law in this cluster es variable and that six cluster stars show very high polarisation values (>4%), probably because of the presence of a nearby small dust cloud. The cluster is at a distance of d=3300pc, it is 2-4Myr old and the initial mass function of its most massive stars (M>3M_{sun}_) has a flat slope of x about of 0.7. As an additional result, it was possible to reconcile the absolute magnitudes of the two WN7-type members using the R-values valid in the regions where they are located.
