scholarly journals Optical hydrogen absorption consistent with a bow shock around the hot Jupiter HD 189733 b

2015 ◽  
Vol 11 (S320) ◽  
pp. 376-381 ◽  
Author(s):  
P. Wilson Cauley ◽  
Seth Redfield ◽  
Adam G. Jensen ◽  
Travis Barman ◽  
Michael Endl ◽  
...  
Keyword(s):  
Stellar Wind ◽  
Bow Shock ◽  
Transmission Spectra ◽  
Shock Model ◽  
Hot Jupiters ◽  
Balmer Lines ◽  
Planetary Magnetic Field ◽  
Host Stars ◽  
Hot Jupiter

AbstractHot Jupiters, i.e., Jupiter-mass planets with orbital semi major axes of <10 stellar radii, can interact strongly with their host stars. If the planet is moving supersonically through the stellar wind, a bow shock will form ahead of the planet where the planetary magnetosphere slams into the the stellar wind or where the planetary outflow and stellar wind meet. Here we present high resolution spectra of the hydrogen Balmer lines for a single transit of the hot Jupiter HD 189733 b. Transmission spectra of the Balmer lines show strong absorption ~70 minutes before the predicted optical transit, implying a significant column density of excited hydrogen orbiting ahead of the planet. We show that a simple geometric bow shock model is able to reproduce the important features of the absorption time series while simultaneously matching the line profile morphology. Our model suggests a large planetary magnetic field strength of ~28 G. Follow-up observations are needed to confirm the pre-transit signal and investigate any variability in the measurement.

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 Multi-Component MHD Model of Hot Jupiter Envelopes

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 422
Author(s):  
Andrey Zhilkin ◽  
Dmitri Bisikalo
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Numerical Model ◽  
Stellar Wind ◽  
Bow Shock ◽  
Model Description ◽  
Hot Jupiters ◽  
Bow Shock Wave ◽  
Field Lines ◽  
Hot Jupiter

A numerical model description of a hot Jupiter extended envelope based on the approximation of multi-component magnetic hydrodynamics is presented. The main attention is focused on the problem of implementing the completed MHD stellar wind model. As a result, the numerical model becomes applicable for calculating the structure of the extended envelope of hot Jupiters not only in the super-Alfvén and sub-Alfvén regimes of the stellar wind flow around and in the trans-Alfvén regime. The multi-component MHD approximation allows the consideration of changes in the chemical composition of hydrogen–helium envelopes of hot Jupiters. The results of calculations show that, in the case of a super-Alfvén flow regime, all the previously discovered types of extended gas-dynamic envelopes are realized in the new numerical model. With an increase in magnitude of the wind magnetic field, the extended envelope tends to become more closed. Under the influence of a strong magnetic field of the stellar wind, the envelope matter does not move along the ballistic trajectory but along the magnetic field lines of the wind toward the host star. This corresponds to an additional (sub-Alfvénic) envelope type of hot Jupiters, which has specific observational features. In the transient (trans-Alfvén) mode, a bow shock wave has a fragmentary nature. In the fully sub-Alfvén regime, the bow shock wave is not formed, and the flow structure is shock-less.

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).

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 Planets spinning up their host stars: a twist on the age-activity relationship

2013 ◽  
Vol 9 (S302) ◽  
pp. 239-242
Author(s):  
K. Poppenhaeger ◽  
S. J. Wolk
Keyword(s):  
Magnetic Activity ◽  
Negative Control ◽  
Detection Methods ◽  
Close Binaries ◽  
Activity Levels ◽  
Planet Detection ◽  
Hot Jupiters ◽  
Cool Stars ◽  
Host Stars ◽  
Hot Jupiter

AbstractIt is a long-standing question in exoplanet research if Hot Jupiters can influence the magnetic activity of their host stars. While cool stars usually spin down with age and become inactive, an input of angular momentum through tidal interaction, as seen for example in close binaries, can preserve high activity levels over time. This may also be the case for cool stars hosting a Hot Jupiter. However, selection effects from planet detection methods often dominate the activity levels seen in samples of exoplanet host stars, and planet-induced, systematically enhanced stellar activity has not been detected unambiguously so far. We have developed an approach to identify planet-induced stellar spin-up avoiding the selection biases from planet detection, by using visual proper motion binaries in which only one of the stars possesses a Hot Jupiter. This approach immediately rids one of the ambiguities of detection biases: with two co-eval stars, the second star acts as a negative control. We present results from our ongoing observational campaign at X-ray wavelengths and in the optical, and present several outstanding systems which display significant age/activity discrepancies presumably caused by their Hot Jupiters.

scholarly journals Modeling the Lyα transit absorption of the hot Jupiter HD 189733b

2020 ◽  
Vol 638 ◽  
pp. A49 ◽  
Author(s):  
P. Odert ◽  
N. V. Erkaev ◽  
K. G. Kislyakova ◽  
H. Lammer ◽  
A. V. Mezentsev ◽  
...  
Keyword(s):  
Stellar Wind ◽  
Extreme Ultraviolet ◽  
Neutral Hydrogen ◽  
Hydrogen Distribution ◽  
Modeling Framework ◽  
X Ray ◽  
Host Stars ◽  
Excess Absorption ◽  
Hot Jupiter

Context. Hydrogen-dominated atmospheres of hot exoplanets expand and escape hydrodynamically due to the intense heating by the X-ray and extreme ultraviolet (XUV) irradiation of their host stars. Excess absorption of neutral hydrogen has been observed in the Lyα line during transits of several close-in gaseous exoplanets, indicating such extended atmospheres. Aims. For the hot Jupiter HD 189733b, this absorption shows temporal variability. We aim to study if variations in stellar XUV emission and/or variable stellar wind conditions may explain this effect. Methods. We applied a 1D hydrodynamic planetary upper atmosphere model and a 3D magnetohydrodynamic stellar wind flow model to study the effect of variations of the stellar XUV irradiation and wind conditions at the planet’s orbit on the neutral hydrogen distribution. This includes the production of energetic neutral atoms (ENAs) and the related Lyα transit signature. Results. We obtain comparable, albeit slightly higher Lyα absorption than that observed in 2011 with a stellar XUV flux of 1.8 × 104 erg cm−2 s−1, rather typical activity conditions for this star. Flares with parameters similar to that observed eight hours before the transit are unlikely to have caused a significant modulation of the transit signature. We find that the resulting Lyα absorption is dominated by atmospheric broadening, whereas the contribution of ENAs is negligible, as they are formed inside the bow shock from decelerated wind ions that are heated to high temperatures. Thus, within our modeling framework and assumptions, we find an insignificant dependence of the absorption on the stellar wind parameters. Conclusions. Since the transit absorption can be modeled with typical stellar XUV and wind conditions, it is possible that the nondetection of the absorption in 2010 was affected by less typical stellar activity conditions, such as a very different magnitude and/or shape of the star’s spectral XUV emission, or temporal and/or spatial variations in Lyα affecting the determination of the transit absorption.

scholarly journals Magnetohydrodynamic modelling of star–planet interaction and associated auroral radio emission

2020 ◽  
Vol 494 (4) ◽  
pp. 5044-5055
Author(s):  
Sam Turnpenney ◽  
J D Nichols ◽  
G A Wynn ◽  
X Jia
Keyword(s):  
Radio Emission ◽  
Stellar Wind ◽  
Derived Relations ◽  
Hot Jupiters ◽  
Cyclotron Maser ◽  
Consistent Picture ◽  
Energy Dissipated ◽  
Analytic Models ◽  
Radio Power ◽  
Hot Jupiter

ABSTRACT We present calculations of auroral radio powers of magnetized hot Jupiters orbiting Sun-like stars, computed using global magnetohydrodynamic (MHD) modelling of the magnetospheric and ionospheric convection arising from the interaction between the magnetosphere and the stellar wind. Exoplanetary auroral radio powers are traditionally estimated using empirical or analytically derived relations, such as the radiometric Bode’s law (RBL), which relates radio power to the magnetic or kinetic energy dissipated in the stellar wind–planet interaction. Such methods risk an oversimplification of the magnetospheric electrodynamics giving rise to radio emission. As the next step towards a self-consistent picture, we model the stellar wind–magnetosphere–ionosphere coupling currents using a 3D MHD model. We compute electron-cyclotron maser instability-driven emission from the calculated ionospheric field-aligned current density. We show that the auroral radio power is highly sensitive to interplanetary magnetic field (IMF) strength, and that the emission is saturated for plausible hot Jupiter Pedersen conductances, indicating that radio power may be largely independent of ionospheric conductance. We estimate peak radio powers of 1014 W from a planet exposed to an IMF strength of 103 nT, implying flux densities at a distance of 15 pc from Earth potentially detectable with current and future radio telescopes. We also find a relation between radio power and planetary orbital distance that is broadly consistent with results from previous analytic models of magnetosphere–ionosphere coupling at hot Jupiters, and indicates that the RBL likely overestimates the radio powers by up to two orders of magnitude in the hot Jupiter regime.

scholarly journals High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP)

2018 ◽  
Vol 610 ◽  
pp. A20 ◽  
Author(s):  
D. F. Evans ◽  
J. Southworth ◽  
B. Smalley ◽  
U. G. Jørgensen ◽  
M. Dominik ◽  
...  
Keyword(s):  
Target Selection ◽  
High Mass ◽  
Line Of Sight ◽  
Companion Star ◽  
Formation Pathway ◽  
Hot Jupiters ◽  
Potential Formation ◽  
History Of ◽  
Host Stars ◽  
Hot Jupiter

Context. The formation and dynamical history of hot Jupiters is currently debated, with wide stellar binaries having been suggested as a potential formation pathway. Additionally, contaminating light from both binary companions and unassociated stars can significantly bias the results of planet characterisation studies, but can be corrected for if the properties of the contaminating star are known. Aim. We search for binary companions to known transiting exoplanet host stars, in order to determine the multiplicity properties of hot Jupiter host stars. We also search for and characterise unassociated stars along the line of sight, allowing photometric and spectroscopic observations of the planetary system to be corrected for contaminating light. Methods. We analyse lucky imaging observations of 97 Southern hemisphere exoplanet host stars, using the Two Colour Instrument on the Danish 1.54 m telescope. For each detected companion star, we determine flux ratios relative to the planet host star in two passbands, and measure the relative position of the companion. The probability of each companion being physically associated was determined using our two-colour photometry. Results. A catalogue of close companion stars is presented, including flux ratios, position measurements, and estimated companion star temperature. For companions that are potential binary companions, we review archival and catalogue data for further evidence. For WASP-77AB and WASP-85AB, we combine our data with historical measurements to determine the binary orbits, showing them to be moderately eccentric and inclined to the line of sight (and hence planetary orbital axis). Combining our survey with the similar Friends of Hot Jupiters survey, we conclude that known hot Jupiter host stars show a deficit of high mass stellar companions compared to the field star population; however, this may be a result of the biases in detection and target selection by ground-based surveys.

scholarly journals WASP-169, WASP-171, WASP-175, and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-South

2019 ◽  
Vol 489 (2) ◽  
pp. 2478-2487 ◽  
Author(s):  
L D Nielsen ◽  
F Bouchy ◽  
O D Turner ◽  
D R Anderson ◽  
K Barkaoui ◽  
...  
Keyword(s):  
Giant Planets ◽  
Outer Planet ◽  
Low Density ◽  
Wide Angle ◽  
Lower Edge ◽  
Velocity Measurements ◽  
Hot Jupiters ◽  
North And South ◽  
Hot Jupiter

ABSTRACT We present the discovery of four new giant planets from the Wide Angle Search for Planets-South (WASP-South), three hot Jupiters and one bloated sub-Saturn mass planet: WASP-169b, WASP-171b, WASP-175b, and WASP-182b. Besides the discovery photometry from WASP-South we use radial velocity measurements from CORALIE and HARPS and follow-up photometry from EulerCam, TRAPPIST-North and -South, and SPECULOOS. WASP-169b is a low-density Jupiter ($M=0.561 \pm 0.061\,{M_{\rm Jup}},\ R=1.304^{+0.150}_{-0.073}\,{R_{\rm Jup}}$) orbiting a V = 12.17 F8 subgiant in a 5.611 d orbit. WASP-171b is a typical hot Jupiter ($M=1.084 \pm 0.094\,{M_{\rm Jup}},\ R=0.98^{+0.07}_{-0.04}\,{R_{\rm Jup}}$, P = 3.82 d) around a V = 13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 yr, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter (M = 0.99 ± 0.13 MJup, R = 1.208 ± 0.081 RJup, P = 3.07 d) around a V = 12.04 F7 star, which possibly is part of a binary system with a star 7.9 arcsec away. WASP-182b is a bloated sub-Saturn mass planet (M = 0.148 ± 0.011 MJup, R = 0.850 ± 0.030 RJup) around a metal-rich V = 11.98 G5 star ([Fe/H] = 0.27 ± 0.11). With an orbital period of P = 3.377 d, it sits right in the apex of the sub-Jovian desert, bordering the upper and lower edge of the desert in both the mass–period and radius–period plane. WASP-169b, WASP-175b, and WASP-182b are promising targets for atmospheric characterization through transmission spectroscopy, with expected transmission signals of 121, 150, and 264 ppm, respectively.

scholarly journals A Precise Carbon and Oxygen Abundance Determination in a Hot Jupiter Atmosphere

2021 ◽  
Author(s):  
Michael Line ◽  
Matteo Brogi ◽  
Jacob Bean ◽  
Siddharth Gandhi ◽  
Joseph Zalesky ◽  
...  
Keyword(s):  
Giant Planet ◽  
High Resolution Spectroscopy ◽  
Relative Role ◽  
Quarter Century ◽  
System Architectures ◽  
Hot Jupiters ◽  
Upper Limits ◽  
Gas Accretion ◽  
Host Stars ◽  
Hot Jupiter

Abstract The origins of gas giant planets orbiting close to their host stars (``hot Jupiters'') remain a mystery despite more than a quarter-century of study (Fortney et al. 2021). The atmospheric compositions of these planets are highly sought after to provide insight to their formation location in protoplanetary disks, how they migrated to be so close to their host stars, and the relative role of solid versus gas accretion during their assembly (Madhusudhan 2019). However, simultaneous, bounded constraints on both carbon and oxygen abundances, which are key for understanding giant planet formation (Oeberg et al. 2011, Mordasini et al. 2016, Madhusudhan et al. 2017,Cridland et al. 2016), have been elusive (Kreidberg et al. 2014,Wakeford et al. 2018,Pelletier et al. 2021). Here, we report precise abundance measurements of both water and carbon monoxide in a hot Jupiter atmosphere via ground-based, high resolution spectroscopy. From these constraints on the primary carbon- and oxygen-bearing molecules, paired with upper limits on other minor volatile elemental carriers, we are able to derive the atmospheric elemental metal enrichment (metallicity) and the carbon-to-oxygen ratio (C/O). The inferred atmospheric metallicity is slightly sub-stellar (-0.48$+0.15/-0.13) and the C/O is consistent with stellar (0.59 ±0.08). The former is suggestive of a metal-depleted atmosphere relative to expectations based on extrapolation from the solar system, indicative of a greater partitioning of metals within the core vs the atmosphere. The C/O constraint rules out gas-dominated accretion followed by disk free migration. Taken together in the context of past inferences, these results point to a diversity of planetary atmospheric compositions in addition to the observed diversity of planetary system architectures.

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