Mass loss of “Hot Jupiters”—Implications for CoRoT discoveries. Part I: The importance of magnetospheric protection of a planet against ion loss caused by coronal mass ejections

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.

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Exoplanet Upper Atmosphere Environment Characterization

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311028316 ◽

2011 ◽

Vol 7 (S282) ◽

pp. 525-532 ◽

Cited By ~ 1

Author(s):

Helmut Lammer ◽

Kristina G. Kislyakova ◽

Petra Odert ◽

Martin Leitzinger ◽

Maxim L. Khodachenko ◽

...

Keyword(s):

Magnetic Properties ◽

Mass Loss ◽

Radiation Exposure ◽

High Temperatures ◽

Stellar Wind ◽

Numerical Models ◽

Large Mass ◽

Upper Atmosphere ◽

Hot Jupiters ◽

Atmosphere Environment

AbstractThe intense stellar SXR and EUV radiation exposure at “Hot Jupiters” causes profound responses to their upper atmosphere structures. Thermospheric temperatures can reach several thousands of Kelvins, which result in dissociation of H2 to H and ionization of H to H+. Depending on the density and orbit location of the exoplanet, as a result of these high temperatures the thermosphere expands dynamically up to the Roche lobe, so that geometric blow-off with large mass loss rates and intense interaction with the stellar wind plasma can occur. UV transit observations together with advanced numerical models can be used to gain knowledge on stellar plasma and the planet's magnetic properties, as well as the upper atmosphere.

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ERRATUM: “SIMULATED PHOTOEVAPORATIVE MASS LOSS FROM HOT JUPITERS IN 3D” (2015, ApJ, 808, 173)

The Astrophysical Journal ◽

10.1088/0004-637x/811/2/159 ◽

2015 ◽

Vol 811 (2) ◽

pp. 159

Author(s):

Anjali Tripathi ◽

Kaitlin M. Kratter ◽

Ruth A. Murray-Clay ◽

Mark R. Krumholz

Keyword(s):

Mass Loss ◽

Hot Jupiters

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Swift UVOT near-UV transit observations of WASP-121 b

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732419 ◽

2019 ◽

Vol 623 ◽

pp. A57 ◽

Cited By ~ 15

Author(s):

M. Salz ◽

P. C. Schneider ◽

L. Fossati ◽

S. Czesla ◽

K. France ◽

...

Keyword(s):

Mass Loss ◽

Spectral Range ◽

Relative Accuracy ◽

Uv Absorption ◽

Absorption Lines ◽

Optical Telescope ◽

Hot Jupiters ◽

Excess Absorption ◽

Loss Rates ◽

Gas Planets

Close-in gas planets are subject to continuous photoevaporation that can erode their volatile envelopes. Today, ongoing mass loss has been confirmed in a few individual systems via transit observations in the ultraviolet spectral range. We demonstrate that the Ultraviolet/Optical Telescope (UVOT) onboard the Neil Gehrels Swift Observatory enables photometry to a relative accuracy of about 0.5% and present the first near-UV (200–270 nm, NUV) transit observations of WASP-121 b, a hot Jupiter with one of the highest predicted mass-loss rates. The data cover the orbital phases 0.85–1.15 with three visits. We measure a broadband NUV transit depth of 2.10 ± 0.29%. While still consistent with the optical value of 1.55%, the NUV data indicate excess absorption of 0.55% at a 1.9σ level. Such excess absorption is known from the WASP-12 system, and both of these hot Jupiters are expected to undergo mass loss at extremely high rates. With a Cloudy simulation, we show that absorption lines of Fe II in a dense extended atmosphere can cause broadband near-UV absorption at the 0.5% level. Given the numerous lines of low-ionization metals, the NUV range is a promising tracer of photoevaporation in the hottest gas planets.

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Influence of Coronal Mass Ejections from the Red Dwarf Component on the Accretion Pattern in CVs and LMXBs

International Astronomical Union Colloquium ◽

10.1017/s0252921100034989 ◽

1995 ◽

Vol 151 ◽

pp. 195-196

Author(s):

Roberto Minarini ◽

Grigory Beskin

Keyword(s):

Mass Loss ◽

Coronal Mass Ejections ◽

Loss Rate ◽

Mass Loss Rate ◽

Magnetic Activity ◽

The Sun ◽

Surface Mass ◽

Red Dwarfs ◽

Low Mass ◽

Transient Events

Low-mass main sequence stars show a magnetic activity similar to the Sun and as a consequence they lose mass in the form of a variable stellar wind. In the latest spectral types (red dwarfs) the activity and the mass loss rate appear to increase by a large factor of ∼ 103 with respect to the solar case, reaching Ṁ ∼ 2 · 10−11 M⊙/yr (Badalyan & Livshits 1992, Katsova 1993). The same happens for coronal mass ejections (CMEs), which are the most relevant transient events of mass loss in these objects. In the Sun, these appear as bubbles of coronal material, with dimensions of some fraction of the solar surface, mass M ≃ 2 · 1014 - 2 · 1016 g and ejection velocity v ≃ 3 · 107 - 2 · 108 cm/s, with an instantaneous mass loss rate Ṁ ∽ 10−13 - 10−11 M⊙/yr (Wagner 1984). In red dwarfs, as recently observed, the ejection velocities are higher, up to v ≃ 3 · 108 cm/s and the mass loss rate can reach the value Ṁ ≃ 10−8 M⊙/yr (Mullan et al. 1989, Houdebine et al. 1990). In both cases, the observations suggest that a bubble expands, once ejected, with a velocity of several hundreds of km/s.

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Measuring and modeling the Balmer series in hot gaseous giant exoplanets

10.5194/epsc2020-115 ◽

2020 ◽

Author(s):

Aurélien Wyttenbach ◽

Paul Mollière ◽

David Ehrenreich ◽

Heather Cegla ◽

Vincent Bourrier ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Atmospheric Model ◽

Balmer Series ◽

Hot Jupiters ◽

Atmospheric Escape ◽

Line Shapes ◽

Early Type Star ◽

Photo Ionization

<p>Atmospheric escape rate is a key parameter to measure in order to understand the evolution of exoplanets. In this presentation, we will show that the Balmer series, observed with high-resolution transmission spectroscopy, is a precise probe to measure exoplanet evaporation, especially for ultra hot Jupiters orbiting early-type star. These&#160;hot gaseous giant exoplanets (such as KELT-9 b) are presumed to have an atmosphere dominated by neutral and ionized atomic species. In particular, hydrogen Balmer&#160;lines have been detected in some of their upper atmospheres, suggesting that hydrogen is filling the planetary Roche lobe and escaping&#160;from these planets. Here, we will present new significant absorptions of the Balmer series in the KELT-9b atmosphere obtained with HARPS-N. The precise line shapes of the H&#945;,&#160;H&#946;, and H&#947; absorptions allow us to put constraints on the thermospheric temperature. Moreover, the mass loss rate, and the excited&#160;hydrogen population of KELT-9 b are also constrained, thanks to a retrieval analysis performed with a new atmospheric model (the PAWN model). We&#160;retrieved a thermospheric temperature of T = 13 200+800-720 K and a mass loss rate of log10(MLR) = 10^(12.8+-0.3) g/s when the atmosphere was&#160;assumed to be in hydrodynamical expansion and in local thermodynamic equilibrium (LTE). Since the thermospheres of hot Jupiters&#160;are not expected to be in LTE, we explored atmospheric structures with non-Boltzmann equilibrium for the population of the excited&#160;hydrogen. We do not find strong statistical evidence in favor of a departure from LTE. However, our non-LTE scenario suggests that a&#160;departure from the Boltzmann equilibrium may not be sufficient to explain the retrieved low number densities of the excited hydrogen.&#160;In non-LTE, Saha equilibrium departure via photo-ionization, is also likely to be necessary to explain the data.</p>

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Five New Hot Jupiter Transits Investigated with Swift-UVOT

The Astronomical Journal ◽

10.3847/1538-3881/ac2c67 ◽

2021 ◽

Vol 162 (6) ◽

pp. 287

Author(s):

Lia Corrales ◽

Sasikrishna Ravi ◽

George W. King ◽

Erin May ◽

Emily Rauscher ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Equilibrium Temperature ◽

Light Curves ◽

X Ray ◽

Hot Jupiters ◽

Upper Limits ◽

Marginal Detection ◽

Optical Radius

Abstract Short-wavelength exoplanet transit measurements have been used to probe mass loss in exoplanet atmospheres. We present the Swift-UVOT transit light curves for five hot Jupiters orbiting UV-bright F-type stars: XO-3, KELT-3, WASP-3, WASP-62, and HAT-P-6. We report one positive transit detection of XO-3b and one marginal detection of KELT-3b. We place upper limits on the remaining three transit depths. The planetary radii derived from the NUV transit depths of both potential detections are 50%–100% larger than their optical radius measurements. We examine the ratio R NUV/R opt for trends as a function of estimated mass-loss rate, which we derive from X-ray luminosity obtained from the Swift-XRT or, in the case of WASP-62, XMM-Newton. We find no correlation between the energy-limited photoevaporative mass-loss rate and the R NUV/R opt ratio. We also search for trends based on the equilibrium temperature of the hot Jupiters. We find a possible indication of a transition in the R NUV/R opt ratio around T eq = 1700 K, analogous to the trends found for NIR water features in transmission spectra. This might be explained by the formation of extended cloud decks with silicate particles ≤1 μm. We demonstrate that the Swift-UVOT filters could be sensitive to absorption from aerosols in exoplanet atmospheres.

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Comparative analysis of the influence of Sgr A* and nearby active galactic nuclei on the mass loss of known exoplanets

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834655 ◽

2019 ◽

Vol 624 ◽

pp. A71 ◽

Cited By ~ 8

Author(s):

A. M. Wisłocka ◽

A. B. Kovačević ◽

A. Balbi

Keyword(s):

Mass Loss ◽

Sloan Digital Sky Survey ◽

Galactic Bulge ◽

Incorrect Choice ◽

Mars Atmosphere ◽

Hot Jupiters ◽

Sagittarius A ◽

Exoplanetary Atmospheres ◽

Sgr A ◽

Atmospheric Mass

Context. The detailed evolution of exoplanetary atmospheres has been the subject of decade-long studies. Only recently, investigations began on the possible atmospheric mass loss caused by the activity of galactic central engines. This question has so far been explored without using available exoplanet data. Aims. The goal of this paper is to improve our knowledge of the erosion of exoplanetary atmospheres through radiation from supermassive black holes (SMBHs) undergoing an active galactic nucleus (AGN) phase. Methods. To this end, we extended the well-known energy-limited mass-loss model to include the case of radiation from AGNs. We set the fraction of incident power ɛ available to heat the atmosphere as either constant (ɛ = 0.1) or flux dependent (ɛ = ɛ(FXUV)). We calculated the possible atmospheric mass loss for 54 known exoplanets (of which 16 are hot Jupiters residing in the Galactic bulge and 38 are Earth-like planets, EPs) due to radiation from the Milky Way’s (MW) central SMBH, Sagittarius A* (Sgr A*), and from a set of 107 220 AGNs generated using the 33 350 AGNs at z < 0.5 of the Sloan Digital Sky Survey database. Results. We found that planets in the Galactic bulge might have lost up to several Earth atmospheres in mass during the AGN phase of Sgr A*, while the EPs are at a safe distance from Sgr A* (>7 kpc) and have not undergone any atmospheric erosion in their lifetimes. We also found that the MW EPs might experience a mass loss up to ~15 times the Mars atmosphere over a period of 50 Myr as the result of exposure to the cumulative extreme-UV flux FXUV from the AGNs up to z = 0.5. In both cases we found that an incorrect choice of ɛ can lead to significant mass loss overestimates.

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