Труды сотрудников ИВМ СО РАН

[Text] / H. Lammer [et al.] // Celest. Mech. Dyn. Astron. - 2005. - Vol. 92, Is. 01.03.2013. - P273-285, DOI 10.1007/s10569-005-0004-4. - Cited References: 27 . - ISSN 0923-2958РУБ Astronomy & Astrophysics + Mathematics, Interdisciplinary Applications

Аннотация: The region around a star where a life-supporting biosphere can evolve is the so-called Habitable Zone (HZ). The current definition of the HZ is based only on the mass-luminosity relation of the star and climatological and meteorological considerations of Earth-like planets, but neglects atmospheric loss processes due to the interaction with the stellar radiation and particle environment. From the knowledge of the planets in the Solar System, we know that planets can only evolve into a habitable world if they have a stable orbit around its host star and if they keep the atmosphere and water inventory during: (i) the period of heavy bombardment by asteroids and comets and (ii) during the host stars' active X-ray and extreme ultraviolet (XUV) and stellar wind periods. Impacts play a minor role for planets with the size and mass like Earth, while high XUV fluxes and strong stellar winds during the active periods of the young host star can destroy the atmospheres and water inventories. We show that XUV produced temperatures in the upper atmospheres of Earth-like planets can lead to hydrodynamic "blow off", resulting in the total loss of the planets water inventory and atmosphere, even if their orbits lie inside the HZ. Further, our study indicates that Earth-like planets inside the HZ of low mass stars may not develop an atmosphere, because at orbital distances closer than 0.3 AU, their atmospheres are highly affected by strong stellar winds and coronal mass ejections (CME's). Our study suggests that planetary magnetospheres will not protect the atmosphere of such planets, because the strong stellar wind of the young star can compress the magnetopause to the atmospheric obstacle. Moreover, planets inside close-in HZ's are tidally locked, therefore, their magnetic moments are weaker than those of an Earth-like planet at 1 AU. Our results indicate that Earth-like planets in orbits of low mass stars may not develop stable biospheres. From this point of view, a HZ, where higher life forms like on Earth may evolve is possibly restricted to higher mass K stars and G stars.


Доп.точки доступа:
Lammer, H.; Kulikov, Y.N.; Penz, T.; Leitner, M.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / N. V. Erkaev [et al.] // Planet Space Sci. - 2014. - Vol. 98. - P. 106-119, DOI 10.1016/j.pss.2013.09.008. - Cited References: 94. - P. Odert, H. Lammer, K. G. Kislyakova and Yu. N. Kulikov acknowledge support from the Helmholtz Alliance project "Planetary Evolution and Life". E. Dorfi, M. Gudel, K. G. Kislyakova, H. Lammer, A. Stokl and E. A. Dorfi acknowledge the Austrian Science Fund (FWF) for supporting this study via the FWF NFN project S116 "Pathways to Habitability: From Disks to Active Stars, Planets and Life", and the related FWF NFN subprojects, S 116 02-N1 "Hydrodynamics in Young Star-Disk Systems", S116 604-N16 "Radiation & Wind Evolution from T Tauri Phase to ZAMS and Beyond", and S11607-N16 "Particle/Radiative Interactions with Upper Atmospheres of Planetary Bodies Under Extreme Stellar Conditions". M. Leitzinger and P. Odert also acknowledge the support from the FWF project P22950-N16. N. V. Erkaev acknowledges support by the RFBR Grant no 12-05-00152-a. Finally, H. Lammer thanks M. lkoma from the Department of Earth and Planetary Science, of the University of Tokyo, Japan, for discussions related to the accumulation of nebular-based hydrogen envelopes around Mars-mass bodies. Finally the authors thank an anonymous referee for the interesting and important suggestions and recommendations that helped to improve the results of our study. . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: Latest research in planet formation indicates that Mars formed within a few million years (Myr) and remained as a planetary embryo that never grew to a more massive planet. It can also be expected from dynamical models that most of Mars' building blocks consisted of material that formed in orbital locations just beyond the ice line which could have contained similar to 0.1-0.2 wt.% of H2O. By using these constraints, we estimate the nebula-captured and catastrophically outgassed volatile contents during the solidification of Mars' magma ocean and apply a hydrodynamic upper atmosphere model for the study of the soft X-ray and extreme ultraviolet (XUV) driven thermal escape of the martian protoatmosphere during the early active epoch of the young Sun. The amount of gas that has been captured from the protoplanetary disk into the planetary atmosphere is calculated by solving the hydrostatic structure equations in the protoplanetary nebula. Depending on nebular properties such as the dust grain depletion factor, planetesimal accretion rates and luminosities, hydrogen envelopes with masses >= 3 x 10(19) g to <= 6.5 x 10(22) g could have been captured from the nebula around early Mars. Depending on the before mentioned parameters, due to the planets low gravity and a solar XUV flux that was similar to 100 times stronger compared to the present value, our results indicate that early Mars would have lost its nebular captured hydrogen envelope after the nebula gas evaporated, during a fast period of similar to 0.1-7.5 Myr. After the solidification of early Mars' magma ocean, catastrophically outgassed volatiles with the amount of similar to 50-250 bar H2O and similar to 10-55 bar CO2 could have been lost during similar to 0.4-12 Myr, if the impact related energy flux of large planetesimals and small embryos to the planet's surface lasted long enough, that the steam atmosphere could have been prevented from condensing. If this was not the case, then our results suggest that the timescales for H2O condensation and ocean formation may have been shorter compared to the atmosphere evaporation timescale, so that one can speculate that sporadically periods, where some amount of liquid water may have been present on the planet's surface. However, depending on the amount of the outgassed volatiles, because of impacts and the high XUV-driven atmospheric escape rates, such sporadically wet surface conditions may have also not lasted much longer than similar to 0.4-12 Myr. After the loss of the captured hydrogen envelope and outgassed volatiles during the first 100 Myr period of the young Sun, a warmer and probably wetter period may have evolved by a combination of volcanic outgassing and impact delivered volatiles similar to 4.0 +/- 0.2 Gyr ago, when the solar XUV flux decreased to values that have been <10 times that of today's Sun. (C) 2013 Elsevier Ltd. All rights reserved.

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ИВМ СО РАН

Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Lammer, H.; Elkins-Tanton, L.T.; Stokl, A.; Odert, P.; Marcq, E.; Dorfi, E.A.; Kislyakova, K.G.; Kulikov, Y.N.; Leitzinger, M.; Gudel, M.; Helmholtz Alliance project "Planetary Evolution and Life"; Austrian Science Fund (FWF); Austrian Science Fund (FWF) via the FWF NFN project [S116]; FWF NFN subprojects [S 116 02-N1, S116 604-N16, S11607-N16]; FWF project [P22950-N16]; RFBR [12-05-00152-a]

/ D. Kubyshkina [et al.] // Astron. Astrophys. - 2018. - Vol. 612. - Ст. A25, DOI 10.1051/0004-6361/201731816. - Cited References:61. - We acknowledge the Austrian Forschungsforderungsgesellschaft FFG project "TAPAS4CHEOPS" P853993, the Austrian Science Fund (FWF) NFN project S11607-N16, and the FWF project P27256-N27. NVE acknowledges support by the RFBR grant No. 15-05-00879-a and 16-52-14006 ANF_a. . - ISSN 1432-0746РУБ Astronomy & Astrophysics

Аннотация: The K2-33 planetary system hosts one transiting similar to 5 R-circle plus planet orbiting the young M-type host star. The planet's mass is still unknown, with an estimated upper limit of 5.4 M-J. The extreme youth of the system (< 20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet's upper atmosphere considering a range of possible planetary masses, from 2 to 40 M-circle plus, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet's mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7-10 M-circle plus, the atmosphere is subject to extremely high escape rates, driven by the planet's weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10 M-circle plus.

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Держатели документа:
Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria.
Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
SB RAS, FRC Krasnoyarsk Sci Ctr, Inst Computat Modelling, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Krasnoyarsk 660041, Russia.
Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.

Доп.точки доступа:
Kubyshkina, D.; Lendl, M.; Fossati, L.; Cubillos, P. E.; Lammer, H.; Erkaev, N. V.; Johnstone, C. P.; Austrian Forschungsforderungsgesellschaft FFG project "TAPAS4CHEOPS" [P853993]; Austrian Science Fund (FWF) NFN project [S11607-N16]; FWF project [P27256-N27]; RFBR grant [15-05-00879-a, 16-52-14006 ANF_a]