We present the discovery of HAT-P-57b, a P = 2.4653 day transiting planet around a V=10.465±0.029 mag, T{sub eff}=7500±250 K main sequence A8V star with a projected rotation velocity of ...vsini=102.1±1.3 km s{sup −1}. We measure the radius of the planet to be R=1.413±0.054 R{sub J} and, based on RV observations, place a 95% confidence upper limit on its mass of M<1.85 M{sub J}.
Various approaches were developed considering the need to increase agricultural productivity in cultivated areas without more deforestation, such as the Integrated Crop livestock systems (ICLS). The ...ICLS could be composed of annual crops followed by pastureland with the presence of cattle. Due to the high temporal dynamic of rotation between crops over the season, monitoring these areas is a big challenge. Also, agricultural organizations worldwide highlight the need for early-season maps for this kind of work. In this context, this study evaluated the potential of open data (Sentinel-2) data to map ICLS areas. The performance of two classifiers was evaluated: one of Machine Learning (random forest) and the other of Deep Learning (LSTM). Three different time windows of data were tested (Entire season, 180 days, and 120 days). Using the RF classifier, it was possible to achieve satisfactory results (Overall accuracy higher than 80%) for the early season (180 days). However, further studies are needed to explain better the lower(when compared to Random Forest) accuracy achieved by LSTM net (0.79 % for 180 days) and compare the results achieved here with results for a study area with different rates of cloud cover.
Disks in binary systems can cause exotic eclipsing events. MWC 882 (BD -22 4376, EPIC 225300403) is such a disk-eclipsing system identified from observations during Campaign 11 of the K2 mission. We ...propose that MWC 882 is a post-Algol system with a B7 donor star of mass in a 72-day orbit around an A0 accreting star of mass . The disk around the accreting star occults the donor star once every orbit, inducing 19-day long, 7% deep eclipses identified by K2 and subsequently found in pre-discovery All-Sky Automated Survey and All Sky Automated Survey for Supernovae observations. We coordinated a campaign of photometric and spectroscopic observations for MWC 882 to measure the dynamical masses of the components and to monitor the system during eclipse. We found the photometric eclipse to be gray to 1%. We found that the primary star exhibits spectroscopic signatures of active accretion, and we observed gas absorption features from the disk during eclipse. We suggest that MWC 882 initially consisted of a 3.6 M donor star transferring mass via Roche lobe overflow to a 2.1 M accretor in a 7-day initial orbit. Through angular momentum conservation, the donor star is pushed outward during mass transfer to its current orbit of 72 days. The observed state of the system corresponds with the donor star having left the red giant branch ∼0.3 Myr ago, terminating active mass transfer. The present disk is expected to be short-lived (102 yr) without an active feeding mechanism, presenting a challenge to this model.
Abstract
Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their ...parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the
Transiting Exoplanet Survey Satellite
. HAT-P-69 b has a mass of
M
Jup
and a radius of
R
Jup
and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of
R
Jup
and a mass constraint of
M
Jup
and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47,126 main-sequence stars brighter than
T
mag
= 10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41 ± 0.10% within this sample, consistent with the rate measured by
Kepler
for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71 ± 0.31% for G stars, 0.43 ± 0.15% for F stars, and 0.26 ± 0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass.
We report the discovery of three new transiting extrasolar planets orbiting moderately bright (V = 11.1, 11.7, and 12.4) F stars. The planets HAT-P-39b through HAT-P-41b have periods of P = 3.5439 ...days, 4.4572 days, and 2.6940 days, masses of 0.60 M sub(J), 0.62 M sub(J), and 0.80 M sub(J), and radii of 1.57 R sub(J), 1.73 R sub(J), and 1.68 R sub(J), respectively. They orbit stars with masses of 1.40 M sub(odot), 1.51 M sub(odot), and 1.51 M sub(odot), respectively. The three planets are members of an emerging population of highly inflated Jupiters with 0.4M sub(J) < M < 1.5 M sub(J) and R gt; 1.5 R sub(J).
Abstract
PDS 110 is a young disc-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a ...closed periodic orbit. In this paper, we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in 2017 September. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for radial velocity (RV) oscillations caused by any hypothetical companion and can rule out close binaries to 0.1Ms. A search of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 yr, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and of shorter duration than those of UX Ori variables, but may have a similar mechanism.
We present the discovery of two transiting exoplanets. HAT-P-28b orbits a V = 13.03 G3 dwarf star with a period P = 3.2572 days and has a mass of 0.63 ? 0.04 M J and a radius of 1.21+0.11 -- 0.08 R J ...yielding a mean density of 0.44 ? 0.09 g cm--3. HAT-P-29b orbits a V = 11.90 F8 dwarf star with a period P = 5.7232 days and has a mass of 0.78+0.08 -- 0.04 M J and a radius of 1.11+0.14 -- 0.08 R J yielding a mean density of 0.71 ? 0.18 g cm--3. We discuss the properties of these planets in the context of other known transiting planets.
We report the discovery and initial characterization of Qatar-1b, a hot Jupiter-orbiting metal-rich K dwarf star, the first planet discovered by the Qatar Exoplanet Survey. We describe the strategy ...used to select candidate transiting planets from photometry generated by the Qatar Exoplanet Survey camera array. We examine the rate of astrophysical and other false positives found during the spectroscopic reconnaissance of the initial batch of candidates. A simultaneous fit to the follow-up radial velocities and photometry of Qatar-1b yields a planetary mass of 1.09 ± 0.08 M
J and a radius of 1.16 ± 0.05 R
J. The orbital period and separation are 1.420 033 ± 0.000 016 d and 0.023 43 ± 0.000 26 au for an orbit assumed to be circular. The stellar density, effective temperature and rotation rate indicate an age greater than 4 Gyr for the system.
We report the discovery of HAT-P-27b, an exoplanet transiting the moderately bright G8 dwarf star GSC 0333-00351 (V = 12.214). The orbital period is 3.039586 ? 0.000012 days, the reference epoch of ...transit is 2455186.01879 ? 0.00054 (BJD), and the transit duration is 0.0705 ? 0.0019 days. The host star with its effective temperature 5300 ? 90 K is somewhat cooler than the Sun and is more metal-rich with a metallicity of +0.29 ? 0.10. Its mass is 0.94 ? 0.04 M and radius is 0.90+0.05 -- 0.04 R . For the planetary companion we determine a mass of 0.660 ? 0.033 M J and radius of 1.038+0.077 -- 0.058 R J. For the 30 known transiting exoplanets between 0.3 M J and 0.8 M J, a negative correlation between host star metallicity and planetary radius and an additional dependence of planetary radius on equilibrium temperature are confirmed at a high level of statistical significance.
We report the discovery of HAT-P-24b, a transiting extrasolar planet orbiting the moderately bright V = 11.818 F8 dwarf star GSC 0774--01441, with a period P = 3.3552464 ? 0.0000071 days, transit ...epoch Tc = 2455216.97669 ? 0.00024 (BJD)11, and transit duration 3.653 ? 0.025 hr. The host star has a mass of 1.191 ? 0.042 M , radius of 1.317 ? 0.068 R , effective temperature 6373 ? 80 K, and a low metallicity of Fe/H = -0.16 ? 0.08. The planetary companion has a mass of 0.681 ? 0.031 M J and radius of 1.243 ? 0.072 R J yielding a mean density of 0.439 ? 0.069 g cm-3. By repeating our global fits with different parameter sets, we have performed a critical investigation of the fitting techniques used for previous Hungarian-made Automated Telescope planetary discoveries. We find that the system properties are robust against the choice of priors. The effects of fixed versus fitted limb darkening are also examined. HAT-P-24b probably maintains a small eccentricity of e = 0.052+0.022 --0.017, which is accepted over the circular orbit model with false alarm probability 5.8%. In the absence of eccentricity pumping, this result suggests that HAT-P-24b experiences less tidal dissipation than Jupiter. Due to relatively rapid stellar rotation, we estimate that HAT-P-24b should exhibit one of the largest known Rossiter-McLaughlin effect amplitudes for an exoplanet ( Delta *DV RM 95 m s--1) and thus a precise measurement of the sky-projected spin-orbit alignment should be possible.
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