scholarly journals Uneven Cooling: The influence of atmospheric dynamics on the thermal evolution of gas giants

2013 ◽  
Vol 8 (S299) ◽  
pp. 380-381
Author(s):  
Emily Rauscher ◽  
Adam P. Showman
Keyword(s):  
Cooling Rate ◽  
Heat Transport ◽  
Thermal Evolution ◽  
Atmospheric Dynamics ◽  
Spherically Symmetric ◽  
Evolutionary Models ◽  
Convective Boundary ◽  
Hot Jupiters ◽  
Global Cooling ◽  
Hot Jupiter

AbstractPlanets cool and contract as they age, with a cooling rate that depends on the efficiency with which they can transport heat out to space, first through the convective interior and then radiatively out through the atmosphere. The bottleneck for this cooling is the radiative-convective boundary (RCB), where the heat transport is the least efficient. Due to differential heating and atmospheric dynamics, the depth of the RCB can vary with latitude and longitude, meaning that the actual global cooling rate may differ from what would be calculated assuming a spherically symmetric RCB, as in 1D evolutionary models. Here we present models of the deep atmosphere of a generic hot Jupiter, calculate inhomogeneity in the RCB, and determine the resulting effect on the global thermal evolution. Although this issue can apply to any differentially heated gas giant, we focus on the hot Jupiter class of planet because: 1) the thick radiative zones above their deep RCBs can have a stronger influence on deforming the surface of the RCB than would generally be the case for a less-irradiated planet, and 2) an uneven RCB should increase the cooling rate, potentially exacerbating the mismatch between the large radii measured for some hot Jupiters and the smaller radii expected from evolutionary models.

scholarly journals Tidally induced stellar oscillations: converting modelled oscillations excited by hot Jupiters into observables

2020 ◽  
Vol 500 (2) ◽  
pp. 2711-2731
Author(s):  
Andrew Bunting ◽  
Caroline Terquem
Keyword(s):  
Radial Velocity ◽  
Orbital Period ◽  
Planetary Systems ◽  
Velocity Signal ◽  
Convective Flux ◽  
Hot Jupiters ◽  
Stellar Oscillations ◽  
Orbital Periods ◽  
Hot Jupiter

ABSTRACT We calculate the conversion from non-adiabatic, non-radial oscillations tidally induced by a hot Jupiter on a star to observable spectroscopic and photometric signals. Models with both frozen convection and an approximation for a perturbation to the convective flux are discussed. Observables are calculated for some real planetary systems to give specific predictions. The photometric signal is predicted to be proportional to the inverse square of the orbital period, P−2, as in the equilibrium tide approximation. However, the radial velocity signal is predicted to be proportional to P−1, and is therefore much larger at long orbital periods than the signal corresponding to the equilibrium tide approximation, which is proportional to P−3. The prospects for detecting these oscillations and the implications for the detection and characterization of planets are discussed.

scholarly journals TOI-150b and TOI-163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ

2019 ◽  
Vol 490 (1) ◽  
pp. 1094-1110 ◽  
Author(s):  
Diana Kossakowski ◽  
Néstor Espinoza ◽  
Rafael Brahm ◽  
Andrés Jordán ◽  
Thomas Henning ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Scale ◽  
High Resolution Spectroscopy ◽  
Spin Orbit ◽  
Eccentric Orbit ◽  
Hot Jupiters ◽  
Eclipse Observations ◽  
James Webb Space Telescope ◽  
Hot Jupiter

Abstract We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a $1.254\pm 0.016\ \rm {R}_ \rm{J}$, massive ($2.61^{+0.19}_{-0.12}\ \rm {M}_ \rm{J}$) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated ($R_ \rm{P}$ = $1.478^{+0.022}_{-0.029} \,\mathrm{ R}_ \rm{J}$, $M_ \rm{P}$ = $1.219\pm 0.11 \, \rm{M}_ \rm{J}$) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit ($e=0.262^{+0.045}_{-0.037}$), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter–McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ).

scholarly journals Secondary eclipse of the hot Jupiter WASP-121b at 2 μm

2019 ◽  
Vol 625 ◽  
pp. A80 ◽  
Author(s):  
Géza Kovács ◽  
Tamás Kovács
Keyword(s):  
Near Infrared ◽  
Infrared Emission ◽  
Current Data ◽  
Emission Analysis ◽  
Hot Jupiters ◽  
Occultation Data ◽  
The One ◽  
Near Infrared Emission ◽  
Absorption Features ◽  
Hot Jupiter

Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1 m class telescope (the SMARTS 1.3 m). We find a highly significant eclipse depth of (0.228 ± 0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e = 0.0207 ± 0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.

Influence of the magnetic field of stellar wind on hot jupiter’s envelopes

2019 ◽  
Vol 15 (S354) ◽  
pp. 268-279
Author(s):  
Dmitry V. Bisikalo ◽  
Andrey G. Zhilkin
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Coronal Mass Ejections ◽  
Stellar Wind ◽  
Roche Lobe ◽  
Bow Shock ◽  
Hot Jupiters ◽  
The Magnetic Field ◽  
Alfven Velocity ◽  
Hot Jupiter

AbstractHot Jupiters have extended gaseous (ionospheric) envelopes, which extend far beyond the Roche lobe. The envelopes are loosely bound to the planet and, therefore, are strongly influenced by fluctuations of the stellar wind. We show that, since hot Jupiters are close to the parent stars, magnetic field of the stellar wind is an important factor defining the structure of their magnetospheres. For a typical hot Jupiter, velocity of the stellar wind plasma flow around the atmosphere is close to the Alfvén velocity. As a result stellar wind fluctuations, such as coronal mass ejections, can affect the conditions for the formation of a bow shock around a hot Jupiter. This effect can affect observational manifestations of hot Jupiters.

scholarly journals Very wide companion fraction from Gaia DR2: A weak or no enhancement for hot Jupiter hosts, and a strong enhancement for contact binaries

2020 ◽  
Vol 497 (2) ◽  
pp. 2250-2259
Author(s):  
Hsiang-Chih Hwang ◽  
Jacob H Hamer ◽  
Nadia L Zakamska ◽  
Kevin C Schlaufman
Keyword(s):  
Main Sequence ◽  
Age Dependence ◽  
Ongoing Debate ◽  
Hot Jupiters ◽  
Field Star ◽  
Random Pairing ◽  
Contact Binaries ◽  
Formation And Evolution ◽  
Gaia Dr2 ◽  
Hot Jupiter

ABSTRACT There is an ongoing debate on whether hot Jupiter hosts are more likely to be found in wide binaries with separations of ≳100 AU. In this paper, we search for comoving, very wide companions with separations of 103–104 AU for hot Jupiter hosts and main-sequence contact binaries in Gaia DR2, and compare the very wide companion fractions with their object-by-object-matched field star samples. We find that 11.9 ± 2.5 per cent of hot Jupiter hosts and 14.1 ± 1.0 per cent of contact binaries have companions at separations of 103–104 AU. While the very wide companion fraction of hot Jupiter hosts is a factor of 1.9 ± 0.5 larger than their matched field star sample, it is consistent, within ∼1σ, with that of matched field stars if the matching is only with field stars without close companions (within ∼50 AU) as is the case for hot Jupiter hosts. The very wide companion fraction of contact binaries is a factor of 3.1 ± 0.5 larger than their matched field star sample, suggesting that the formation and evolution of contact binaries are either tied to or correlated with the presence of wide companions. In contrast, the weak enhancement of very wide companion fraction for hot Jupiter hosts implies that the formation of hot Jupiters is not as sensitive to those environment properties. Our results also hint that the occurrence rates of dual hot Jupiter hosts and dual contact binaries may be higher than the expected values from random pairing of field stars, which may be due to their underlying metallicity and age dependence.

Exoplanets: Atmospheres of Hot Jupiters

2019 ◽  
Author(s):  
Dmitry V. Bisikalo ◽  
Pavel V. Kaygorodov ◽  
Valery I. Shematovich
Keyword(s):  
Solar System ◽  
Alternative Hypothesis ◽  
Atmospheric Composition ◽  
Current Status ◽  
Hot Jupiters ◽  
History Of ◽  
Exoplanetary Atmospheres ◽  
Host Stars ◽  
Gaseous Envelopes ◽  
Hot Jupiter

The history of exoplanetary atmospheres studies is strongly based on the observations and investigations of the gaseous envelopes of hot Jupiters—exoplanet gas giants that have masses comparable to the mass of Jupiter and orbital semi-major axes shorter than 0.1 AU. The first exoplanet around a solar-type star was a hot Jupiter discovered in 1995. Researchers found an object that had completely atypical parameters compared to planets known in the solar system. According to their estimates, the object might have a mass about a half of the Jovian mass and a very short orbital period (four days), which means that it has an orbit roughly corresponding to the orbit of Mercury. Later, many similar objects were discovered near different stars, and they acquired a common name—hot Jupiters. It is still unclear what the mechanism is for their origin, because generally accepted theories of planetary evolution predict the formation of giant planets only at large orbital distances, where they can accrete enough matter before the protoplanetary disc disappears. If this is true, before arriving at such low orbits, hot Jupiters might have a long migration path, caused by interactions with other massive planets and/or with the gaseous disc. In favor of this model is the discovery of many hot Jupiters in elliptical and highly inclined orbits, but on the other hand several observed hot Jupiters have circular orbits with low inclination. An alternative hypothesis is that the cores of future hot Jupiters are super-Earths that may later intercept matter from the protoplanetary disk falling on the star. The scientific interest in hot Jupiters has two aspects. The first is the peculiarity of these objects: they have no analogues in the solar system. The second is that, until recently, only for hot Jupiters was it possible to obtain observational characteristics of their atmospheres. Many of the known hot Jupiters are eclipsing their host stars, so, from their light curve and spectral data obtained during an eclipse, it became possible to obtain information about their shape and their atmospheric composition. Thus it is possible to conclude that hot Jupiters are a common type of exoplanet, having no analogues in the solar system. Many aspects of their evolution and internal structure remain unclear. Being very close to their host stars, hot Jupiters must interact with the stellar wind and stellar magnetic field, as well as with stellar flares and coronal mass ejections, allowing researchers to gather information about them. According to UV observations, at least a fraction of hot Jupiters have extended gaseous envelopes, extending far beyond of their upper atmospheres. The envelopes are observable with current astronomical instruments, so it is possible to develop their astrophysical models. The history of hot Jupiter atmosphere studies during the past 20 years and the current status of modern theories describing the extended envelopes of hot Jupiters are excellent examples of the progress in understanding planetary atmospheres formation and evolution both in the solar system and in the extrasolar planetary systems.

scholarly journals WASP-180Ab: Doppler tomography of a hot Jupiter orbiting the primary star in a visual binary

2019 ◽  
Vol 490 (2) ◽  
pp. 2467-2474
Author(s):  
L Y Temple ◽  
C Hellier ◽  
D R Anderson ◽  
K Barkaoui ◽  
F Bouchy ◽  
...  
Keyword(s):  
Binary Systems ◽  
Rotation Speed ◽  
Small Sample ◽  
Primary Star ◽  
Doppler Tomography ◽  
Companion Star ◽  
Hot Jupiters ◽  
Rotational Modulation ◽  
Hot Jupiter

ABSTRACT We report the discovery and characterization of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9  ±  0.1 MJup, 1.24  ±  0.04 RJup planet to be in a misaligned, retrograde orbit around an F7 star with Teff  =  6500 K and a moderate rotation speed of vsin i⋆  =  19.9 km s−1. The host star is the primary of a V  =  10.7 binary, where a secondary separated by ∼5 arcsec (∼1200 au) contributes ∼ 30 per cent of the light. WASP-180Ab therefore adds to a small sample of transiting hot Jupiters known in binary systems. A 4.6-d modulation seen in the WASP data is likely to be the rotational modulation of the companion star, WASP-180B.

scholarly journals THERMAL EVOLUTION OF A RADIATING ANISOTROPIC STAR WITH SHEAR

2006 ◽  
Vol 15 (07) ◽  
pp. 1053-1065 ◽  
Author(s):  
N. F. NAIDU ◽  
M. GOVENDER ◽  
K. S. GOVINDER
Keyword(s):  
Heat Flux ◽  
Relaxation Time ◽  
Heat Dissipation ◽  
Thermal Evolution ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Pressure Anisotropy ◽  
Radiating Star ◽  
Anisotropic Star

We study the effects of pressure anisotropy and heat dissipation in a spherically symmetric radiating star undergoing gravitational collapse. An exact solution of the Einstein field equations is presented in which the model has a Friedmann-like limit when the heat flux vanishes. The behavior of the temperature profile of the evolving star is investigated within the framework of causal thermodynamics. In particular, we show that there are significant differences between the relaxation time for the heat flux and the relaxation time for the shear stress.

Genesis and Features of Dust Devil-Like Vortices in Convective Boundary Layers – A Numerical Study Using LES and DNS

2020 ◽  
Author(s):  
Sebastian Giersch ◽  
Siegfried Raasch
Keyword(s):  
Boundary Layer ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Heat Transport ◽  
Vortex Core ◽  
Dust Particles ◽  
Dust Devil ◽  
Dust Devils ◽  
Convective Boundary ◽  
Rayleigh Numbers

<p>Dust devils are convective vortices with a vertical axis of rotation mainly characterized by a local minimum in pressure and a local maximum in vertical vorticity within the vortex core. They are made visible by entrained dust particles. That's why they occur primarily in dry and hot areas. Currently, there is great uncertainty about the extent to which dust devils contribute to the atmospheric aerosol and heat transport and thereby influence earth's radiation budget as well as boundary layer properties. Past efforts to quantify the aerosol or heat transport and to study dust devils' formation, maintenance, and statistics using large-eddy simulation (LES) as well as direct numerical simulation (DNS) have been of limited success. Therefore, this study aims to provide better statistical information about dust devil-like structures and to extend, prove or disprove existing theories about the development and maintenance of dust devils. Especially, the vortex strength measured through the pressure drop in the vortex core is regarded, which is, in past LES simulations, almost one order of magnitude smaller compared to the observed range of several hundreds Pascals. <br>So far, we are able to reproduce observed core pressures with LES of the convective boundary layer by using a high spatial resolution of 2m while considering a domain of 4km x 4km x 2km, a model setup with moderate background wind and a spatially heterogeneous surface heat flux. It is found that vortices mainly appear at the vertices and branches of the cellular pattern and at lines of horizontal flow convergence above the centers of the strongly heated patches. The latter result is in contrast to some older observations in which vortices seemed to be created along the patch edges. Also further statistical properties, like lifetimes, diameters or frequency of occurrence, fit quite well in the observed range. Nevertheless, statistics of dust devils from LES face the general problem that they are highly influenced by the used grid spacing and thereby by the structures that can be explicitly resolved. For example, the near surface layer, which plays a major role for the vortex development, is poorly resolved and turbulent processes in this layer are highly parameterized. DNS would overcome this problem. Therefore, dust devil-like structures are also investigated with DNS by simulating laboratory-like Rayleigh-Bénard convection with Rayleigh numbers up to 10<sup>12</sup>. Such high Rayleigh numbers have never been used in DNS studies of dust devils. The focus is on the vortex formation dependence on the used Rayleigh number and aspect ratio. First results of the laboratory-like Rayleigh-Bénard convection simulated with DNS confirm the existence of dust devil-like structures also on small scales with much lower Rayleigh numbers than in the atmosphere. <br>In a next step, detailed statistics of dust devil-like structures in Rayleigh-Bénard convection will be derived focusing on Rayleigh number and aspect ratio dependencies. Afterwards, results will be compared to LES simulations of dust devils and experimental data.</p>

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