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[Text] / G. F. Jaritz [et al.] // Astron. Astrophys. - 2005. - Vol. 439, Is. 2. - P771-775, DOI 10.1051/0004-6361:20052946. - Cited References: 32 . - ISSN 0004-6361РУБ Astronomy & Astrophysics

Аннотация: Theoretical studies and recent observational evidence of the expansion of the atmospheres of short-periodic exoplanets show that the atmospheres extend up to several planetary radii. This indicates that the atmospheres experience blow-off conditions. Because of the short orbital distance to their host stars, the expansion of the upper atmosphere is no longer radially symmetric, but depends on the direction to the central body, resulting in a deformation of the expanded atmosphere. We show the connection between atmospheric expansion, tidal forces and effects of the Roche potential and find that HD209458 b, OGLE-TR-10 b and OGLE-TR-111 b are most likely in a state of classical hydrodynamical blow-off because the distance where blow-off can occur is less than the distance to the Lagrangian point L1. On the other hand, OGLE-TR-56 b, OGLE-TR-113 b, OGLE-TR-132 b and TreS-1 experience a geometrical blow-off defined by the Roche lobe as proposed by Lecavelier des Etangs et al. (2004, A&A, 418, L1). Our results have important implications for the evolution of short periodic gas giants, because the Roche lobe overflow of the atmosphere can lead to lower mass loss rates over the exoplanets history, compared to gas giants which experience hydrodynamic expansion and loss unaffected by this boundary. Thus, massive exoplanets like OGLE-TR-56 b in very close orbital distances are subject to geometrical blow-off conditions, this results in a total mass loss for this particular exoplanet of the order of about 3 x 10(-2) M-pl over the planets age, even if current mass loss rates of about 2 x 10(11) g s(-1) are calculated. If the exoplanet effected by the geometrical blow-off is more massive, the mass loss rate is even lower. However, giant exoplanets like HD209458 b, OGLE-TR-10 b and OGLE-TR-111 b at orbital distances of about 0.05 AU may experience classical hydrodynamic blow-off conditions, which can result in higher mass loss rates. Thus, such planets may shrink to their core sizes during the X-ray and EUV active periods of their host stars as proposed by Lammer et al. ( 2003, ApJ, L121, 598) and Bara. e et al. (2004, A& A, 419, L13).


Доп.точки доступа:
Jaritz, G.F.; Endler, S.; Langmayr, D.; Lammer, H.; Griessmeier, J.M.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.

/ P. Odert [et al.] // Icarus. - 2018. - Vol. 307. - P327-346, DOI 10.1016/j.icarus.2017.10.031. - Cited References:136. - PO and HL acknowledge support from the Austrian Science Fund (FWF): P27256-N27. NVE acknowledges RFBR grant No 16-52-14006 ANF_a. AN and NT acknowledge support from the Helmholtz Association (project VH-NG-1017). This work was supported by the FWF NFN project S11601-N16 'Pathways to Habitability: From Disks to Active Stars, Planets and Life' and the related subprojects S11604-N16 and S11607-N16. The authors also acknowledge the International Space Science Institute (ISSI, Bern, Switzerland) and the ISSI team 'The Early Evolution of the Atmospheres of Earth, Venus, and Mars'. We thank the two anonymous referees for helpful comments which significantly improved the paper. . - ISSN 0019-1035. - ISSN 1090-2643РУБ Astronomy & Astrophysics

Аннотация: Planetary embryos form protoplanets via mutual collisions, which can lead to the development of magma oceans. During their solidification, significant amounts of the mantles' volatile contents may be outgassed. The resulting H2O/CO2 dominated steam atmospheres may be lost efficiently via hydrodynamic escape due to the low gravity of these Moon- to Mars-sized objects and the high stellar EUV luminosities of the young host stars. Protoplanets forming from such degassed building blocks after nebula dissipation could therefore be drier than previously expected. We model the outgassing and subsequent hydrodynamic escape of steam atmospheres from such embryos. The efficient outflow of H drags along heavier species like O, CO2, and noble gases. The full range of possible EUV evolution tracks of a young solar-mass star is taken into account to investigate the atmospheric escape from Mars-sized planetary embryos at different orbital distances. The estimated envelopes are typically lost within a few to a few tens of Myr. Furthermore, we study the influence on protoplanetary evolution, exemplified by Venus. In particular, we investigate different early evolution scenarios and constrain realistic cases by comparing modeled noble gas isotope ratios with present observations. Isotope ratios of Ne and Ar can be reproduced, starting from solar values, under hydrodynamic escape conditions. Solutions can be found for different solar EUV histories, as well as assumptions about the initial atmosphere, assuming either a pure steam atmosphere or a mixture with accreted hydrogen from the protoplanetary nebula. Our results generally favor an early accretion scenario with a small amount of residual hydrogen from the protoplanetary nebula and a low-activity Sun, because in other cases too much CO2 is lost during evolution, which is inconsistent with Venus' present atmosphere. Important issues are likely the time at which the initial steam atmosphere is outgassed and/or the amount of CO2 which may still be delivered at later evolutionary stages. A late accretion scenario can only reproduce present isotope ratios for a highly active young Sun, but then unrealistically massive steam atmospheres (few kbar) would be required. (C) 2017 Elsevier Inc. All rights reserved.

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Держатели документа:
Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria.
Russian Acad Sci, Siberian Branch, Inst Computat Modelling, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Krasnoyarsk 660041, Russia.
German Aerosp Ctr DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany.
Tech Univ Berlin, Str 17 Juni 135, D-10623 Berlin, Germany.
Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
Karl Franzens Univ Graz, IGAM, Inst Phys, Univ Pl 5, A-8010 Graz, Austria.

Доп.точки доступа:
Odert, P.; Lammer, H.; Erkaev, N. V.; Nikolaou, A.; Lichtenegger, H. I. M.; Johnstone, C. P.; Kislyakova, K. G.; Leitzinger, N.; Tosi, N.; Nikolaou, Athanasia; Austrian Science Fund (FWF) [P27256-N27]; RFBR [16-52-14006 ANF_a]; Helmholtz Association [VH-NG-1017]; FWF NFN [S11601-N16, S11604-N16, S11607-N16]

/ D. Kubyshkina [et al.] // Astrophys. J. - 2019. - Vol. 879, Is. 1. - Ст. 26, DOI 10.3847/1538-4357/ab1e42. - Cited References:44. - We acknowledge the FFG project P853993, the FWF/NFN projects S11607-N16 and S11604-N16, and the FWF projects P27256-N27 and P30949-N36. N.V.E. acknowledges support from the Russian Science Foundation grant No. 18-12-00080. We thank the anonymous referee for insightful comments. . - ISSN 0004-637X. - ISSN 1538-4357РУБ Astronomy & Astrophysics

Аннотация: Planet atmospheric escape induced by high-energy stellar irradiation is a key phenomenon shaping the structure and evolution of planetary atmospheres. Therefore, the present-day properties of a planetary atmosphere are intimately connected with the amount of stellar flux received by a planet during its lifetime, thus with the evolutionary path of its host star. Using a recently developed analytic approximation based on hydrodynamic simulations for atmospheric escape rates, we track within a Bayesian framework the evolution of a planet as a function of stellar flux evolution history, constrained by the measured planetary radius. We find that the ideal objects for this type of study are close-in sub-Neptune-like planets, as they are highly affected by atmospheric escape, and yet retain a significant fraction of their primordial hydrogen-dominated atmospheres. Furthermore, we apply this analysis to the HD 3167 and K2-32 planetary systems. For HD 3167, we find that the most probable irradiation level at 150 Myr was between 40 and 130 times solar, corresponding to a rotation period of 1.78(-1.23)(+2.69) days. For K2-32, we find a surprisingly low irradiation level ranging between half and four times solar at 150 Myr. Finally, we show that for multi-planet systems, our framework enables one to constrain poorly known properties of individual planets.

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Держатели документа:
Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria.
Russian Acad Sci, Siberian Branch, Inst Computat Modeling, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Krasnoyarsk 660041, Russia.
Univ Vienna, Inst Astron, Turkenschanzstr 17, A-1180 Vienna, Austria.
Karl Franzens Univ Graz, IGAM Inst Phys, Univ Pl 5, A-8010 Graz, Austria.

Доп.точки доступа:
Kubyshkina, D.; Cubillos, P. E.; Fossati, L.; Erkaev, N. V.; Johnstone, C. P.; Kislyakova, K. G.; Lammer, H.; Lendl, M.; Odert, P.; Gudel, M.; Fossati, Luca; FFG project [P853993]; FWF/NFN projects [S11607-N16, S11604-N16]; FWF projects [P27256-N27, P30949-N36]; Russian Science Foundation [18-12-00080]