scholarly journals Three short-period Jupiters from TESS

2020 ◽  
Vol 639 ◽  
pp. A76 ◽  
Author(s):  
L. D. Nielsen ◽  
R. Brahm ◽  
F. Bouchy ◽  
N. Espinoza ◽  
O. Turner ◽  
...  
Keyword(s):  
Stellar System ◽  
Phase Curve ◽  
Mass Determination ◽  
Tidal Dissipation ◽  
Giant Star ◽  
Hot Jupiters ◽  
Short Period ◽  
Host Stars ◽  
Interesting System

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 MJ planet in a grazing transit configuration with an impact parameter of b = 1.17−0.08+0.10. As a result the radius is poorly constrained, 2.03−0.49+0.61RJ. The planet’s distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Qs′ = 107 − 109. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13 MJ and a radius of 1.29 ± 0.02 RJ. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06 MJ and a radius of 1.09−0.05+0.08RJ. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to0.24.

scholarly journals Constraining Planetary Migration Mechanisms in Systems of Giant Planets

2013 ◽  
Vol 8 (S299) ◽  
pp. 386-390
Author(s):  
Rebekah I. Dawson ◽  
Ruth A. Murray-Clay ◽  
John Asher Johnson
Keyword(s):  
Giant Planet ◽  
Giant Planets ◽  
Tidal Dissipation ◽  
Hot Jupiters ◽  
Short Period ◽  
Pile Up ◽  
Planetary Migration ◽  
Multi Body ◽  
Host Stars

AbstractIt was once widely believed that planets formed peacefully in situ in their proto-planetary disks and subsequently remain in place. Instead, growing evidence suggests that many giant planets undergo dynamical rearrangement that results in planets migrating inward in the disk, far from their birthplaces. However, it remains debated whether this migration is caused by smooth planet-disk interactions or violent multi-body interactions. Both classes of model can produce Jupiter-mass planets orbiting within 0.1 AU of their host stars, also known as hot Jupiters. In the latter class of model, another planet or star in the system perturbs the Jupiter onto a highly eccentric orbit, which tidal dissipation subsequently shrinks and circularizes during close passages to the star. We assess the prevalence of smooth vs. violent migration through two studies. First, motivated by the predictions of Socrates et al. (2012), we search for super-eccentric hot Jupiter progenitors by using the “photoeccentric effect” to measure the eccentricities of Kepler giant planet candidates from their transit light curves. We find a significant lack of super- eccentric proto-hot Jupiters compared to the number expected, allowing us to place an upper limit on the fraction of hot Jupiters created by stellar binaries. Second, if both planet-disk and multi-body interactions commonly cause giant planet migration, physical properties of the proto-planetary environment may determine which is triggered. We identify three trends in which giant planets orbiting metal rich stars show signatures of planet-planet interactions: (1) gas giants orbiting within 1 AU of metal-rich stars have a range of eccentricities, whereas those orbiting metal- poor stars are restricted to lower eccentricities; (2) metal-rich stars host most eccentric proto-hot Jupiters undergoing tidal circularization; and (3) the pile-up of short-period giant planets, missing in the Kepler sample, is a feature of metal-rich stars and is largely recovered for giants orbiting metal-rich Kepler host stars. These two studies suggest that both disk migration and planet-planet interactions may be widespread, with the latter occurring primarily in metal-rich planetary systems where multiple giant planets can form. Funded by NSF-GRFP DGE-1144152.

Discovering the atmospheres of hot Jupiters

2019 ◽  
Vol 15 (S354) ◽  
pp. 467-472
Author(s):  
P. Wilson Cauley
Keyword(s):  
Detailed Characterization ◽  
Hot Jupiters ◽  
Short Period ◽  
The Future ◽  
To Come ◽  
Host Stars

AbstractHot Jupiters are an extraordinary class of exoplanets, orbiting their host stars with periods of hours to a few days. Some of these objects have day-side temperatures approaching photospheric temperatures of late K-type stars. I will give an overview of how we characterize the atmospheres of these fascinating objects and some the more recent exciting results to come from ground and space-based telescopes, as well as what the future holds for detailed characterization of short-period exoplanet atmospheres.

scholarly journals TESS unveils the phase curve of WASP-33b

2020 ◽  
Vol 639 ◽  
pp. A34 ◽  
Author(s):  
C. von Essen ◽  
M. Mallonn ◽  
C. C. Borre ◽  
V. Antoci ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Light Curve ◽  
Signal To Noise Ratio ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Brightness Temperatures ◽  
Pulsation Spectrum ◽  
Stellar Pulsations ◽  
Detailed Determination

We present the detection and characterization of the full-orbit phase curve and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths, along with the pulsation spectrum of the host star. We analyzed data collected by the Transiting Exoplanet Survey Satellite (TESS) in sector 18. WASP-33b belongs to a very short list of highly irradiated exoplanets that were discovered from the ground and were later visited by TESS. The host star of WASP-33b is of δ Scuti-type and shows nonradial pulsations in the millimagnitude regime, with periods comparable to the period of the primary transit. These completely deform the photometric light curve, which hinders our interpretations. By carrying out a detailed determination of the pulsation spectrum of the host star, we find 29 pulsation frequencies with a signal-to-noise ratio higher than 4. After cleaning the light curve from the stellar pulsations, we confidently report a secondary eclipse depth of 305.8 ± 35.5 parts-per-million (ppm), along with an amplitude of the phase curve of 100.4 ± 13.1 ppm and a corresponding westward offset between the region of maximum brightness and the substellar point of 28.7 ± 7.1 degrees, making WASP-33b one of the few planets with such an offset found so far. Our derived Bond albedo, AB = 0.369 ± 0.050, and heat recirculation efficiency, ɛ = 0.189 ± 0.014, confirm again that he behavior of WASP-33b is similar to that of other hot Jupiters, despite the high irradiation received from its host star. By connecting the amplitude of the phase curve to the primary transit and depths of the secondary eclipse, we determine that the day- and nightside brightness temperatures of WASP-33b are 3014 ± 60 K and 1605 ± 45 K, respectively. From the detection of photometric variations due to gravitational interactions, we estimate a planet mass of MP = 2.81 ± 0.53 MJ. Based on analyzing the stellar pulsations in the frame of the planetary orbit, we find no signals of star-planet interactions.

scholarly journals Nonlinear tidal flows in short-period planets

2019 ◽  
Vol 82 ◽  
pp. 43-50
Author(s):  
A.J. Barker
Keyword(s):  
Extrasolar Planets ◽  
Spin Orbit ◽  
Tidal Evolution ◽  
Tidal Dissipation ◽  
Hot Jupiters ◽  
Fluid Instability ◽  
Short Period ◽  
Elliptical Instability ◽  
Turbulent Damping ◽  
Tidal Deformations

I discuss two related nonlinear mechanisms of tidal dissipation that require finite tidal deformations for their operation: the elliptical instability and the precessional instability. Both are likely to be important for the tidal evolution of short-period extrasolar planets. The elliptical instability is a fluid instability of elliptical streamlines, such as in tidally deformed non-synchronously rotating or non-circularly orbiting planets. I summarise the results of local and global simulations that indicate this mechanism to be important for tidal spin synchronisation, planetary spin-orbit alignment and orbital circularisation for the shortest period hot Jupiters. The precessional instability is a fluid instability that occurs in planets undergoing axial precession, such as those with spin-orbit misalignments (non-zero obliquities). I summarise the outcome of local MHD simulations designed to study the turbulent damping of axial precession, which suggest this mechanism to be important in driving tidal evolution of the spin-orbit angle for hot Jupiters. Avenues for future work are also discussed.

scholarly journals Searching for reflected light from τ Bootis b with high-resolution ground-based spectroscopy: Approaching the 10−5 contrast barrier

2018 ◽  
Vol 610 ◽  
pp. A47 ◽  
Author(s):  
H. J. Hoeijmakers ◽  
I. A. G. Snellen ◽  
S. E. van Terwisga
Keyword(s):  
Meta Analysis ◽  
Phase Curve ◽  
High Dispersion ◽  
Stellar Spectrum ◽  
Hot Jupiters ◽  
Reflected Light ◽  
Theoretical Predictions ◽  
The Subject ◽  
Host Stars ◽  
Expected Signal

Context. It is challenging to measure the starlight reflected from exoplanets because of the extreme contrast with their host stars. For hot Jupiters, this contrast is in the range of 10−6 to 10−4, depending on their albedo, radius and orbital distance. Searches for reflected light have been performed since the first hot Jupiters were discovered, but with very limited success because hot Jupiters tend to have low albedo values due to the general absence of reflective cloud decks. Aims. The aim of this study is to search for reflected light from τ Boo b, a hot Jupiter with one of the brightest host stars. Since its discovery in 1997, it has been the subject of several reflected-light searches using high-dispersion spectroscopy. Here we aim to combine these data in to a single meta-analysis. Methods. We analysed more than 2000 archival high-dispersion spectra obtained with the UVES, ESPaDOnS, NARVAL UES and HARPS-N spectrographs during various epochs between 1998 and 2013. Each spectrum was first cleaned of the stellar spectrum and subsequently cross-correlated with a PHOENIX model spectrum. These were then Doppler shifted to the planet rest-frame and co-added in time, weighted according to the expected signal-to-noise of the planet signal. Results. We reach a 3σ upper limit of the planet-to-star contrast of 1.5 × 10−5. Assuming a planet radius of 1.15 RJ, this corresponds to an optical albedo of 0.12 between 400–700 nm. A low albedo is in line with secondary eclipse and phase curve observations of other hot Jupiters using space-based observatories, as well as theoretical predictions of their reflective properties.

scholarly journals A hot Saturn on an eccentric orbit around the giant star K2-132

2018 ◽  
Vol 613 ◽  
pp. A76 ◽  
Author(s):  
M. I. Jones ◽  
R. Brahm ◽  
N. Espinoza ◽  
A. Jordán ◽  
F. Rojas ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Semimajor Axis ◽  
Physical Parameters ◽  
Giant Star ◽  
Orbital Parameters ◽  
Hot Jupiters ◽  
Giant Stars ◽  
Short Period ◽  
Interesting Object ◽  
Solar Type

Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P ≲ 10 days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017, AJ, 154, 254). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff = 4878 ± 70 K, log g = 3.289 ± 0.004, and [Fe/H] = −0.11 ± 0.05 dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P = 9.1708 ± 0.0025 d, e = 0.290 ± 0.049, Mp = 0.495 ± 0.007 MJ and Rp = 1.089 ± 0.006 RJ. This is the fifth known planet orbiting any giant star with a < 0.1, and the most eccentric one among them, making K2-132 b a very interesting object.

scholarly journals The ominous fate of exomoons around hot Jupiters in the high-eccentricity migration scenario

2020 ◽  
Vol 499 (3) ◽  
pp. 4195-4205
Author(s):  
Alessandro A Trani ◽  
Adrian S Hamers ◽  
Aaron Geller ◽  
Mario Spera
Keyword(s):  
Migration Process ◽  
High Eccentricity ◽  
Primary Star ◽  
Tidal Dissipation ◽  
Hot Jupiters ◽  
Tidal Interactions ◽  
Extrasolar Systems ◽  
Natural Satellites ◽  
Planetary Migration ◽  
Host Stars

ABSTRACT All the giant planets in the Solar system host a large number of natural satellites. Moons in extrasolar systems are difficult to detect, but a Neptune-sized exomoon candidate has been recently found around a Jupiter-sized planet in the Kepler-1625b system. Due to their relative ease of detection, hot Jupiters (HJs), which reside in close orbits around their host stars with a period of a few days, may be very good candidates to search for exomoons. It is still unknown whether the HJ population can host (or may have hosted) exomoons. One suggested formation channel for HJs is high-eccentricity migration induced by a stellar binary companion combined with tidal dissipation. Here, we investigate under which circumstances an exomoon can prevent or allow high-eccentricity migration of a HJ, and in the latter case, if the exomoon can survive the migration process. We use both semi-analytic arguments, as well as direct N-body simulations including tidal interactions. Our results show that massive exomoons are efficient at preventing high-eccentricity migration. If an exomoon does instead allow for planetary migration, it is unlikely that the HJ formed can host exomoons since the moon will either spiral on to the planet or escape from it during the migration process. A few escaped exomoons can become stable planets after the Jupiter has migrated, or by tidally migrating themselves. The majority of the exomoons end up being ejected from the system or colliding with the primary star and the host planet. Such collisions might none the less leave observable features, such as a debris disc around the primary star or exorings around the close-in giant.

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