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 detection of a transiting super-Earth-sized planet (
R
= 1.39 ± 0.09
R
⊕
) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (
V
= 11,
K
= 7.1) located at 25.15 ± 0.02 pc. ...The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS and
Magellan
/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60 ± 0.56
M
⊕
and thus the bulk density to be 1.74
−0.33
+0.44
times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission’s scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future atmospheric characterization.
ABSTRACT We present Hubble Space Telescope (HST) optical and near-ultraviolet transmission spectra of the transiting hot Jupiter HD189733b, taken with the repaired Space Telescope Imaging ...Spectrograph (STIS) instrument. The resulting spectra cover the range 2900-5700Å and reach per exposure signal-to-noise ratio levels greater than 11000 within a 500-Å bandwidth. We used time series spectra obtained during two transit events to determine the wavelength dependence of the planetary radius and measure the exoplanet's atmospheric transmission spectrum for the first time over this wavelength range. Our measurements, in conjunction with existing HST spectra, now provide a broad-band transmission spectrum covering the full optical regime. The STIS data also show unambiguous evidence of a large occulted stellar spot during one of our transit events, which we use to place constraints on the characteristics of the K dwarf's stellar spots, estimating spot temperatures around Teff 4250K. With contemporaneous ground-based photometric monitoring of the stellar variability, we also measure the correlation between the stellar activity level and transit-measured planet-to-star radius contrast, which is in good agreement with predictions. We find a planetary transmission spectrum in good agreement with that of Rayleigh scattering from a high-altitude atmospheric haze as previously found from HST Advanced Camera for Surveys. The high-altitude haze is now found to cover the entire optical regime and is well characterized by Rayleigh scattering. These findings suggest that haze may be a globally dominant atmospheric feature of the planet which would result in a high optical albedo at shorter optical wavelengths. PUBLICATION ABSTRACT
ABSTRACT We report the discovery of EPIC 201702477b, a transiting brown dwarf in a long period (40.73691 0.00037 day) and eccentric (e = 0.2281 0.0026) orbit. This system was initially reported as a ...planetary candidate based on two transit events seen in K2 Campaign 1 photometry and later validated as an exoplanet candidate. We confirm the transit and refine the ephemeris with two subsequent ground-based detections of the transit using the Las Cumbres Observatory Global Telescope 1 m telescope network. We rule out any transit timing variations above the level of ∼30 s. Using high precision radial velocity measurements from HARPS and SOPHIE we identify the transiting companion as a brown dwarf with a mass, radius, and bulk density of 66.9 1.7 MJ, 0.757 0.065 RJ, and 191 51 g cm−3 respectively. EPIC 201702477b is the smallest radius brown dwarf yet discovered, with a mass just below the H-burning limit. It has the highest density of any planet, substellar mass object, or main-sequence star discovered so far. We find evidence in the set of known transiting brown dwarfs for two populations of objects-high mass brown dwarfs and low mass brown dwarfs. The higher-mass population have radii in very close agreement to theoretical models, and show a lower-mass limit around 60 MJ. This may be the signature of mass-dependent ejection of systems during the formation process.
AbstractWe present the analysis of KIC 8164262, a heartbeat star with a high-amplitude (∼1 mmag), tidally resonant pulsation (a mode in resonance with the orbit) at 229 times the orbital frequency ...and a plethora of tidally induced g-mode pulsations (modes excited by the orbit). The analysis combines Kepler light curves with follow-up spectroscopic data from the Keck telescope, KPNO (Kitt Peak National Observatory) 4-m Mayall telescope and the 2.7-m telescope at the McDonald observatory. We apply the binary modelling software, phoebe, to the Kepler light curve and radial velocity data to determine a detailed binary star model that includes the prominent pulsation and Doppler boosting, alongside the usual attributes of a binary star model (including tidal distortion and reflection). The results show that the system contains a slightly evolved F star with an M secondary companion in a highly eccentric orbit (e = 0.886). We use the results of the binary star model in a companion paper (Fuller) where we show that the prominent pulsation can be explained by a tidally excited oscillation mode held near resonance by a resonance locking mechanism.
This Letter reports on the photometric detection of transits of the Neptune-mass planet orbiting the nearby M-dwarf star GJ 436. It is by far the closest, smallest, and least massive transiting ...planet detected so far. Its mass is slightly larger than Neptune's at $M = 22.6 \pm 1.9~M_\oplus $. The shape and depth of the transit lightcurves show that it is crossing the host star disc near its limb (impact parameter $0.84 \pm 0.03$) and that the planet size is comparable to that of Uranus and Neptune, $R = 25\,200 \pm 2200$ km = $3.95 \pm 0.35~R_\oplus$. Its main constituant is therefore very likely to be water ice. If the current planet structure models are correct, an outer layer of H/He constituting up to ten percent in mass is probably needed on top of the ice to account for the observed radius.
We present multiwavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our ...observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of 1 month, and recorded multiple transit events with depths varying between ~20 and 50 per cent. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained on two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5-1.2 ...m. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2... lower limit of 0.8 ...m on the grain size in the putative transiting debris cloud. This conclusion is consistent with the spectral energy distribution of the system, which can be fit with an optically thin debris disc with minimum particle sizes of 10... ...m. (ProQuest: ... denotes formulae/symbols omitted.)
Using Campaign 15 data from theK2mission, we have discovered a triply eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 d, withshallow∼3 per cent ...eclipses. During the entire 80-d campaign, there is also a single eclipse event of a third body in the system that reaches a depth of nearly 50 per cent and has a total duration of 1.7 d, longer than for any previously known third-body eclipse involving unevolved stars. The binary eclipses exhibit clear eclipse timing variations. A combination of photodynamical modeling of the light curve, as well as seven follow-up radial velocity measurements, has led to a prediction of the subsequent eclipses of the third star with a period of 188 d. A campaign of follow-up ground-based photometry was able to capture the subsequent pair of third-body events as well as two further 8-d eclipses. A combined photo-spectro-dynamical analysis then leads to the determination of many of the system parameters. The 8-d binary consists of a pair of M stars, while most of the system light is from a K star around which the pair of M stars orbits.
Heartbeat stars are eccentric (e > 0.2) ellipsoidal variables whose light curves resemble a cardiogram. We present the observations and corresponding model of KIC 3749404, a highly eccentric (e = ...0.66), short period (P = 20.3 d) heartbeat star with tidally induced pulsations. A binary star model was created using phoebe, which we modified to include tidally induced pulsations and Doppler boosting. The morphology of the photometric periastron variation (heartbeat) depends strongly on the eccentricity, inclination and argument of periastron. We show that the inclusion of tidally induced pulsations in the model significantly changes the parameter values, specifically the inclination and those parameters dependent on it. Furthermore, we determine the rate of apsidal advance by modelling the periastron variation at the beginning and end of the 4-yr Kepler data set and dividing by the elapsed time. We compare the model with the theoretical expectations for classical and general relativistic apsidal motion and find the observed rate to be two orders of magnitude greater than the theoretical rate. We find that the observed rate cannot be explained by tidally induced pulsations alone and consequently hypothesize the presence of a third body in the system.
Context.
TOI-2076 is a transiting three-planet system of sub-Neptunes orbiting a bright (
G
= 8.9 mag), young (340 ± 80 Myr) K-type star. Although a validated planetary system, the orbits of the two ...outer planets were unconstrained as only two non-consecutive transits were seen in TESS photometry. This left 11 and 7 possible period aliases for each.
Aims.
To reveal the true orbits of these two long-period planets, precise photometry targeted on the highest-probability period aliases is required. Long-term monitoring of transits in multi-planet systems can also help constrain planetary masses through TTV measurements.
Methods.
We used the MonoTools package to determine which aliases to follow, and then performed space-based and ground-based photometric follow-up of TOI-2076 c and d with CHEOPS, SAINT-EX, and LCO telescopes.
Results.
CHEOPS observations revealed a clear detection for TOI-2076 c at $P = 21.02538_{ - 0.00074}^{ + 0.00084}$ d, and allowed us to rule out three of the most likely period aliases for TOI-2076 d. Ground-based photometry further enabled us to rule out remaining aliases and confirm the
P
= 35.12537 ± 0.00067 d alias. These observations also improved the radius precision of all three sub-Neptunes to 2.518 ± 0.036, 3.497 ± 0.043, and 3.232 ± 0.063
R
⊕
. Our observations also revealed a clear anti-correlated TTV signal between planets b and c likely caused by their proximity to the 2:1 resonance, while planets c and d appear close to a 5:3 period commensurability, although model degeneracy meant we were unable to retrieve robust TTV masses. Their inflated radii, likely due to extended H-He atmospheres, combined with low insolation makes all three planets excellent candidates for future comparative transmission spectroscopy with JWST.
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