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Your search keyword '"Khodachenko, M. L."' showing total 175 results
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175 results on '"Khodachenko, M. L."'

153. Determining the mass loss limit for close-in exoplanets: what can we learn from transit observations?

Author

Lammer, H., primary, Odert, P., additional, Leitzinger, M., additional, Khodachenko, M. L., additional, Panchenko, M., additional, Kulikov, Yu. N., additional, Zhang, T. L., additional, Lichtenegger, H. I. M., additional, Erkaev, N. V., additional, Wuchterl, G., additional, Micela, G., additional, Penz, T., additional, Biernat, H. K., additional, Weingrill, J., additional, Steller, M., additional, Ottacher, H., additional, Hasiba, J., additional, and Hanslmeier, A., additional

Published
2009
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155. Decametric observations of active M-dwarfs

Author

Leitzinger, M., primary, Odert, P., additional, Hanslmeier, A., additional, Konovalenko, A. A., additional, Vanko, M., additional, Khodachenko, M. L., additional, Lammer, H., additional, Rucker, H. O., additional, and Stempels, Eric, additional

Published
2009
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156. A catalogue of nearby M stars

Author

Odert, P., primary, Leitzinger, M., additional, Hanslmeier, A., additional, Lammer, H., additional, Khodachenko, M. L., additional, Ribas, I., additional, Vanko, M., additional, Konovalenko, A. A., additional, Rucker, H. O., additional, and Stempels, Eric, additional

Published
2009
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161. Damping of oscillations by ion-neutral collisions in a prominence plasma

Author

Forteza, P., Oliver, R., Ballester, J. L., Khodachenko, M. L., Forteza, P., Oliver, R., Ballester, J. L., and Khodachenko, M. L.

Abstract

Aims.The role of collisions between ions, electrons and neutrals in a partially ionised plasma is assessed as a possible wave damping mechanism. The relevance of this mechanism in the damping of small amplitude prominence oscillations is evaluated.

Published
2007
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162. On the Efficiency of Radio Emissions at the Double Plasma Frequency in the Magnetosphere of Exoplanet HD189733b.

Author

Zaitsev, V. V., Shaposhnikov, V. E., Khodachenko, M. L., and Rumenskikh, M. S.

Subjects
*PLASMA frequencies, *SECOND harmonic generation, *PLASMA waves, *MAGNETOSPHERE, *ELECTROMAGNETIC waves, *RAMAN scattering, *ELECTRON plasma, *EXTRASOLAR planets
Abstract

On exoplanets with a weak magnetic field, the so-called plasma maser can be effectively implemented instead of an electron cyclotron maser. This maser involves the generation of plasma waves by energetic electrons and their conversion into radio emissions at the plasma frequency or at the double frequency. Under specific conditions, a maser effect occurs at the plasma frequency, which manifests itself in an exponential increase in radio emissions intensity with an increase in the energy of plasma waves. In this paper, we study the Raman scattering of excited plasma waves with the formation of an electromagnetic wave at the double plasma frequency in the plasmasphere of the exoplanet HD189733b, for which the three-dimensional structure of the plasma envelope has been studied. Although the maser effect is absent in the case of Raman scattering, the collisional absorption of radiation is significantly reduced at the second harmonic and the requirement for the brightness temperature in the source is reduced as well. It has been shown that the radio flux at the second harmonic increases sharply for this exoplanet from a few millijanskys at a frequency of 20 MHz to tens of janskys at a frequency of ≈4 MHz. This means that the decameter range near the cutoff frequency of the Earth's ionosphere is the most promising range for the detection of second harmonic radio emissions by modern radio telescopes. In this case, the radio emissions of the second harmonic can provide information about the properties of plasmaspheres around exoplanets at considerable distances that are inaccessible during observations at the main plasma frequencies. [ABSTRACT FROM AUTHOR]

Published
2023
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163. MAGNETODISK-DOMINATED MAGNETOSPHERES OF CLOSE ORBIT GIANT EXOPLANETS.

Author

Khodachenko, M. L., Alexeev, I. I., Belenkaya, E. S., and Lammer, H.

Subjects
*MAGNETOSPHERE, *EXTRASOLAR planets, *STELLAR radiation, *MAGNETIC fields, *MAGNETIC dipoles
Abstract

A more complete view of a magnetosphere of a close orbit giant exoplanet, so called "Hot Jupiter", based on the Paraboloid Magnetospheric Model (PMM), is proposed. The key element of the considered model consists in taking into account the effects of an expanding upper atmosphere of a Hot Jupiter heated and ionized by the stellar XUV radiation. As a result, an extended magnetodisk is built around the planet. The magnetic field produced by magnetodisk ring currents, dominates above the contribution of intrinsic magnetic dipole of a Hot Jupiter and finally determines the size and shape of the whole magnetosphere. [ABSTRACT FROM AUTHOR]

Published
2013
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164. MAGNETOSPHERES OF "HOT JUPITERS": THE IMPORTANCE OF MAGNETODISKS IN SHAPING A MAGNETOSPHERIC OBSTACLE.

Author

Khodachenko, M. L., Alexeev, I., Belenkaya, E., Lammeri, H., Grießmeier, J.-M., Leitzingir, M., Odert, P., Zaqarashvi, T., and Rucker, H. O.

Subjects
EXTRASOLAR planets, MAGNETOSPHERE, STELLAR activity, PLASMA gas research, MAGNETOSPHERE of Jupiter, JUPITER (Planet)
Abstract

Weak intrinsic magnetic dipole moments of tidally locked close-in giant exoplanets ("hot Jupiters") have been shown in previous studies to be unable to provide an efficient magnetospheric protection for their expanding upper atmospheres against the stellar plasma flow, which should lead to significant non-thermal atmosphere mass loss. The present work provides a more complete view of the magnetosphere structure of "hot Jupiters," based on a paraboloid magnetospheric model (PMM). Besides the intrinsic planetary magnetic dipole, the PMM considers among the main magnetic field sources also the electric current system of the magnetotail, magnetopause currents, and the ring current of a magnetodisk. Due to the outflow of ionized particles from the hydrodynamically expanding upper atmosphere, "hot Jupiters" may have extended magnetodisks. The magnetic field produced by magnetodisk ring currents dominates above the contribution of an intrinsic magnetic dipole of a "hot Jupiter" and finally determines the size and shape of the whole magnetosphere. A slower-than-the-dipole-type decrease of the magnetic field with the distance forms the essential specifics of magnetodisk-dominated magnetospheres of "hot Jupiters." This results in their 40%-70% larger scales compared to those traditionally estimated by only the planetary dipole taken into account. Therefore, the formation of magnetodisks has to be included in the studies of the stellar wind plasma interaction with close-in exoplanets, as well as magnetospheric protection for planetary atmospheres against non-thermal escape due to erosion by the stellar plasma flow. [ABSTRACT FROM AUTHOR]

Published
2012
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167. Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters

Author

Erkaev, N. V., Odert, P., Lammer, H., Kislyakova, K. G., Fossati, L., Мезенцев, Александр Владимирович, Johnstone, C. P., Kubyshkina, D. I., Shaikhislamov, I. F., Khodachenko, M. L., Erkaev, N. V., Odert, P., Lammer, H., Kislyakova, K. G., Fossati, L., Мезенцев, Александр Владимирович, Johnstone, C. P., Kubyshkina, D. I., Shaikhislamov, I. F., and Khodachenko, M. L.

Abstract

We investigate the interaction between themagnetized stellarwind plasma and the partially ionized hydrodynamic hydrogen outflow from the escaping upper atmosphere of non-magnetized or weakly magnetized hot Jupiters. We use the well-studied hot Jupiter HD 209458b as an example for similar exoplanets, assuming a negligible intrinsic magnetic moment. For this planet, the stellar wind plasma interaction forms an obstacle in the planet’s upper atmosphere, in which the position of the magnetopause is determined by the condition of pressure balance between the stellar wind and the expanded atmosphere, heated by the stellar extreme ultraviolet radiation.We show that the neutral atmospheric atoms penetrate into the region dominated by the stellar wind, where they are ionized by photoionization and charge exchange, and then mixed with the stellar wind flow. Using a 3D magnetohydrodynamic (MHD) model, we show that an induced magnetic field forms in front of the planetary obstacle, which appears to be much stronger compared to those produced by the solar wind interaction with Venus and Mars. Depending on the stellar wind parameters, because of the induced magnetic field, the planetary obstacle can move up to ≈0.5–1 planetary radii closer to the planet. Finally, we discuss how estimations of the intrinsic magnetic moment of hot Jupiters can be inferred by coupling hydrodynamic upper planetary atmosphere andMHDstellar wind interaction models together with UV observations. In particular, we find that HD 209458b should likely have an intrinsic magnetic moment of 10–20 per cent that of Jupiter.

168. The PLATO 2.0 mission

Author

Rauer, H., Catala, C., Aerts, C., Appourchaux, T., Benz, W., Brandeker, A., Christensen-Dalsgaard, J., Deleuil, M., Gizon, L., Goupil, M.-J., Güdel, M., Janot-Pacheco, E., Mas-Hesse, M., Pagano, I., Piotto, G., Pollacco, D., Santos, Ċ., Smith, A., Suárez, J.-C., Szabó, R., Udry, S., Adibekyan, V., Alibert, Y., Almenara, J.-M., Amaro-Seoane, P., Eiff, M. Ammler-von, Asplund, M., Antonello, E., Barnes, S., Baudin, F., Belkacem, K., Bergemann, M., Bihain, G., Birch, A. C., Bonfils, X., Boisse, I., Bonomo, A. S., Borsa, F., Brandão, I. M., Brocato, E., Brun, S., Burleigh, M., Burston, R., Cabrera, J., Cassisi, S., Chaplin, W., Charpinet, S., Chiappini, C., Church, R. P., Csizmadia, Sz., Cunha, M., Damasso, M., Davies, M. B., Deeg, H. J., Díaz, R. F., Dreizler, S., Dreyer, C., Eggenberger, P., Ehrenreich, D., Eigmüller, P., Erikson, A., Farmer, R., Feltzing, S., Oliveira Fialho, F. de, Figueira, P., Forveille, T., Fridlund, M., García, R. A., Giommi, P., Giuffrida, G., Godolt, M., da Silva, J. Gomes, Granzer, T., Grenfell, J. L., Grotsch-Noels, A., Günther, E., Haswell, C. A., Hatzes, A. P., Hébrard, G., Hekker, S., Helled, R., Heng, K., Jenkins, J. M., Johansen, A., Khodachenko, M. L., Kislyakova, K. G., Kley, W., Kolb, U., Krivova, N., Kupka, F., Lammer, H., Lanza, A. F., Lebreton, Y., Magrin, D., Marcos-Arenal, P., Marrese, P. M., Marques, J. P., Martins, J., Mathis, S., Mathur, S., Messina, S., Miglio, A., Montalban, J., Montalto, M., P. F. G. Monteiro, M. J., Moradi, H., Moravveji, E., Mordasini, C., Morel, T., Mortier, A., Nascimbeni, V., Nelson, R. P., Nielsen, M. B., Noack, L., Norton, A. J., Ofir, A., Oshagh, M., Ouazzani, R.-M., Pápics, P., Parro, V. C., Petit, P., Plez, B., Poretti, E., Quirrenbach, A., Ragazzoni, R., Raimondo, G., Rainer, M., Reese, D. R., Redmer, R., Reffert, S., Rojas-Ayala, B., Roxburgh, I. W., Salmon, S., Santerne, A., Schneider, J., Schou, J., Schuh, S., Schunker, H., Silva-Valio, A., Silvotti, R., Skillen, I., Snellen, I., Sohl, F., Sousa, S. G., Sozzetti, A., Stello, D., Strassmeier, K. G., Švanda, M., Szabó, Gy. M., Tkachenko, A., Valencia, D., Van Grootel, V., Vauclair, S. D., Ventura, P., Wagner, F. W., Walton, N. A., Weingrill, J., Werner, S. C., Wheatley, P. J., Zwintz, K., Rauer, H., Catala, C., Aerts, C., Appourchaux, T., Benz, W., Brandeker, A., Christensen-Dalsgaard, J., Deleuil, M., Gizon, L., Goupil, M.-J., Güdel, M., Janot-Pacheco, E., Mas-Hesse, M., Pagano, I., Piotto, G., Pollacco, D., Santos, Ċ., Smith, A., Suárez, J.-C., Szabó, R., Udry, S., Adibekyan, V., Alibert, Y., Almenara, J.-M., Amaro-Seoane, P., Eiff, M. Ammler-von, Asplund, M., Antonello, E., Barnes, S., Baudin, F., Belkacem, K., Bergemann, M., Bihain, G., Birch, A. C., Bonfils, X., Boisse, I., Bonomo, A. S., Borsa, F., Brandão, I. M., Brocato, E., Brun, S., Burleigh, M., Burston, R., Cabrera, J., Cassisi, S., Chaplin, W., Charpinet, S., Chiappini, C., Church, R. P., Csizmadia, Sz., Cunha, M., Damasso, M., Davies, M. B., Deeg, H. J., Díaz, R. F., Dreizler, S., Dreyer, C., Eggenberger, P., Ehrenreich, D., Eigmüller, P., Erikson, A., Farmer, R., Feltzing, S., Oliveira Fialho, F. de, Figueira, P., Forveille, T., Fridlund, M., García, R. A., Giommi, P., Giuffrida, G., Godolt, M., da Silva, J. Gomes, Granzer, T., Grenfell, J. L., Grotsch-Noels, A., Günther, E., Haswell, C. A., Hatzes, A. P., Hébrard, G., Hekker, S., Helled, R., Heng, K., Jenkins, J. M., Johansen, A., Khodachenko, M. L., Kislyakova, K. G., Kley, W., Kolb, U., Krivova, N., Kupka, F., Lammer, H., Lanza, A. F., Lebreton, Y., Magrin, D., Marcos-Arenal, P., Marrese, P. M., Marques, J. P., Martins, J., Mathis, S., Mathur, S., Messina, S., Miglio, A., Montalban, J., Montalto, M., P. F. G. Monteiro, M. J., Moradi, H., Moravveji, E., Mordasini, C., Morel, T., Mortier, A., Nascimbeni, V., Nelson, R. P., Nielsen, M. B., Noack, L., Norton, A. J., Ofir, A., Oshagh, M., Ouazzani, R.-M., Pápics, P., Parro, V. C., Petit, P., Plez, B., Poretti, E., Quirrenbach, A., Ragazzoni, R., Raimondo, G., Rainer, M., Reese, D. R., Redmer, R., Reffert, S., Rojas-Ayala, B., Roxburgh, I. W., Salmon, S., Santerne, A., Schneider, J., Schou, J., Schuh, S., Schunker, H., Silva-Valio, A., Silvotti, R., Skillen, I., Snellen, I., Sohl, F., Sousa, S. G., Sozzetti, A., Stello, D., Strassmeier, K. G., Švanda, M., Szabó, Gy. M., Tkachenko, A., Valencia, D., Van Grootel, V., Vauclair, S. D., Ventura, P., Wagner, F. W., Walton, N. A., Weingrill, J., Werner, S. C., Wheatley, P. J., and Zwintz, K.

Abstract

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet di

169. The PLATO 2.0 mission

Author

Rauer, H., Catala, C., Aerts, C., Appourchaux, T., Benz, W., Brandeker, A., Christensen-Dalsgaard, J., Deleuil, M., Gizon, L., Goupil, M.-J., Güdel, M., Janot-Pacheco, E., Mas-Hesse, M., Pagano, I., Piotto, G., Pollacco, D., Santos, Ċ., Smith, A., Suárez, J.-C., Szabó, R., Udry, S., Adibekyan, V., Alibert, Y., Almenara, J.-M., Amaro-Seoane, P., Eiff, M. Ammler-von, Asplund, M., Antonello, E., Barnes, S., Baudin, F., Belkacem, K., Bergemann, M., Bihain, G., Birch, A. C., Bonfils, X., Boisse, I., Bonomo, A. S., Borsa, F., Brandão, I. M., Brocato, E., Brun, S., Burleigh, M., Burston, R., Cabrera, J., Cassisi, S., Chaplin, W., Charpinet, S., Chiappini, C., Church, R. P., Csizmadia, Sz., Cunha, M., Damasso, M., Davies, M. B., Deeg, H. J., Díaz, R. F., Dreizler, S., Dreyer, C., Eggenberger, P., Ehrenreich, D., Eigmüller, P., Erikson, A., Farmer, R., Feltzing, S., Oliveira Fialho, F. de, Figueira, P., Forveille, T., Fridlund, M., García, R. A., Giommi, P., Giuffrida, G., Godolt, M., da Silva, J. Gomes, Granzer, T., Grenfell, J. L., Grotsch-Noels, A., Günther, E., Haswell, C. A., Hatzes, A. P., Hébrard, G., Hekker, S., Helled, R., Heng, K., Jenkins, J. M., Johansen, A., Khodachenko, M. L., Kislyakova, K. G., Kley, W., Kolb, U., Krivova, N., Kupka, F., Lammer, H., Lanza, A. F., Lebreton, Y., Magrin, D., Marcos-Arenal, P., Marrese, P. M., Marques, J. P., Martins, J., Mathis, S., Mathur, S., Messina, S., Miglio, A., Montalban, J., Montalto, M., P. F. G. Monteiro, M. J., Moradi, H., Moravveji, E., Mordasini, C., Morel, T., Mortier, A., Nascimbeni, V., Nelson, R. P., Nielsen, M. B., Noack, L., Norton, A. J., Ofir, A., Oshagh, M., Ouazzani, R.-M., Pápics, P., Parro, V. C., Petit, P., Plez, B., Poretti, E., Quirrenbach, A., Ragazzoni, R., Raimondo, G., Rainer, M., Reese, D. R., Redmer, R., Reffert, S., Rojas-Ayala, B., Roxburgh, I. W., Salmon, S., Santerne, A., Schneider, J., Schou, J., Schuh, S., Schunker, H., Silva-Valio, A., Silvotti, R., Skillen, I., Snellen, I., Sohl, F., Sousa, S. G., Sozzetti, A., Stello, D., Strassmeier, K. G., Švanda, M., Szabó, Gy. M., Tkachenko, A., Valencia, D., Van Grootel, V., Vauclair, S. D., Ventura, P., Wagner, F. W., Walton, N. A., Weingrill, J., Werner, S. C., Wheatley, P. J., Zwintz, K., Rauer, H., Catala, C., Aerts, C., Appourchaux, T., Benz, W., Brandeker, A., Christensen-Dalsgaard, J., Deleuil, M., Gizon, L., Goupil, M.-J., Güdel, M., Janot-Pacheco, E., Mas-Hesse, M., Pagano, I., Piotto, G., Pollacco, D., Santos, Ċ., Smith, A., Suárez, J.-C., Szabó, R., Udry, S., Adibekyan, V., Alibert, Y., Almenara, J.-M., Amaro-Seoane, P., Eiff, M. Ammler-von, Asplund, M., Antonello, E., Barnes, S., Baudin, F., Belkacem, K., Bergemann, M., Bihain, G., Birch, A. C., Bonfils, X., Boisse, I., Bonomo, A. S., Borsa, F., Brandão, I. M., Brocato, E., Brun, S., Burleigh, M., Burston, R., Cabrera, J., Cassisi, S., Chaplin, W., Charpinet, S., Chiappini, C., Church, R. P., Csizmadia, Sz., Cunha, M., Damasso, M., Davies, M. B., Deeg, H. J., Díaz, R. F., Dreizler, S., Dreyer, C., Eggenberger, P., Ehrenreich, D., Eigmüller, P., Erikson, A., Farmer, R., Feltzing, S., Oliveira Fialho, F. de, Figueira, P., Forveille, T., Fridlund, M., García, R. A., Giommi, P., Giuffrida, G., Godolt, M., da Silva, J. Gomes, Granzer, T., Grenfell, J. L., Grotsch-Noels, A., Günther, E., Haswell, C. A., Hatzes, A. P., Hébrard, G., Hekker, S., Helled, R., Heng, K., Jenkins, J. M., Johansen, A., Khodachenko, M. L., Kislyakova, K. G., Kley, W., Kolb, U., Krivova, N., Kupka, F., Lammer, H., Lanza, A. F., Lebreton, Y., Magrin, D., Marcos-Arenal, P., Marrese, P. M., Marques, J. P., Martins, J., Mathis, S., Mathur, S., Messina, S., Miglio, A., Montalban, J., Montalto, M., P. F. G. Monteiro, M. J., Moradi, H., Moravveji, E., Mordasini, C., Morel, T., Mortier, A., Nascimbeni, V., Nelson, R. P., Nielsen, M. B., Noack, L., Norton, A. J., Ofir, A., Oshagh, M., Ouazzani, R.-M., Pápics, P., Parro, V. C., Petit, P., Plez, B., Poretti, E., Quirrenbach, A., Ragazzoni, R., Raimondo, G., Rainer, M., Reese, D. R., Redmer, R., Reffert, S., Rojas-Ayala, B., Roxburgh, I. W., Salmon, S., Santerne, A., Schneider, J., Schou, J., Schuh, S., Schunker, H., Silva-Valio, A., Silvotti, R., Skillen, I., Snellen, I., Sohl, F., Sousa, S. G., Sozzetti, A., Stello, D., Strassmeier, K. G., Švanda, M., Szabó, Gy. M., Tkachenko, A., Valencia, D., Van Grootel, V., Vauclair, S. D., Ventura, P., Wagner, F. W., Walton, N. A., Weingrill, J., Werner, S. C., Wheatley, P. J., and Zwintz, K.

Abstract

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet di

170. 3D aeronomy of two mini-neptunes in the HD 63433 system and their in-transit absorption in Ly α and metastable He i lines.

Author

Berezutsky, A G, Shaikhislamov, I F, Rumenskikh, M S, Miroshnichenko, I B, Khodachenko, M  L, Golubovskii, M P, and Sharipov, S S

Subjects
*STELLAR winds, *OUTER planets, *NATURAL satellites, *UPPER atmosphere, *DETECTION limit
Abstract

The numerical simulation of the HD 63433 system is performed with the aim to study upper atmospheres of two mini-Neptunes, planets b and c, interacting with the stellar wind of the parent star. The obtained results demonstrate that both exoplanets form the extended envelopes with strong supersonic outflows. The synthetic absorption profiles in the Ly α line show that under moderate stellar wind conditions, similar to those of the normal solar wind, the energetic neutral atoms contribute to the absorption in the high-velocity blue wing of the line at a level of tens per cent. The absorption in metastable helium He  i (23S) line appears rather weak and below the detection limit by current instruments. An important feature revealed by the simulations is that the tail of escaping atmospheric material of the inner planet disturbs the stellar wind at orbital location of the outer planet and might, therefore, affect its observation in Ly α line. [ABSTRACT FROM AUTHOR]

Published
2024
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171. Aeronomy of the Atmosphere of Ultra-Hot Jupiter Kelt9b with Allowance for the Kinetics of Hydrogen Atom Levels.

Author

Shaikhislamov, I. F., Miroshnichenko, I. B., Rumenskikh, M. S., Shepelin, A. V., Berezutsky, A. G., Sharipov, S. S., Golubovsky, M. P., Chibranov, A. A., and Khodachenko, M. L.

Subjects
*ATMOSPHERE of Jupiter, *HYDROGEN atom, *STELLAR atmospheres, *ROCHE equipotentials, *PLANETARY atmospheres
Abstract

Ultra-hot Jupiter Kelt9b impels to reconsider existing models of the upper atmospheres of hot exoplanets, which were previously developed using examples of G or M star systems such as HD209458b and GJ436b. The unique conditions of interaction between the radiation of an A-class star and the atmosphere necessitate kinetic modeling of excited levels of elements, primarily the hydrogen atom. Kelt9b shows the absorption for several Balmer lines and lines of a number of heavy elements, the quantitative interpretation of which is an urgent problem. In this study, for the first time, 3D modeling of the atmosphere of a planet with a close location of the Roche lobe is implemented with allowance for the aeronomy and kinetics of excited hydrogen. [ABSTRACT FROM AUTHOR]

Published
2024
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173. On the transit spectroscopy features of warm Neptunes in the TOI-421 system, revealed with their 3D aeronomy simulations.

Author

Berezutsky, A G, Shaikhislamov, I F, Rumenskikh, M S, Khodachenko, M L, Lammer, H, and Miroshnichenko, I B

Subjects
*UPPER atmosphere, *PLASMA flow, *ASTRONOMICAL transits, *STELLAR winds, *SPECTROMETRY, *BL Lacertae objects, *X-ray absorption near edge structure
Abstract

We simulate with a global 3D aeronomy code two warm Neptunes in the TOI-421 system and show that both planets experience significant escape of their upper atmospheres. The double shock structures, generated around the planets in course of their interaction with the stellar wind (SW) plasma flow are revealed. The calculations of stellar Ly α transit absorption by the planets reveal that it reaches a detectable level only for a moderate or strong SW, with a sufficiently high density. In this case, the energetic neutral atoms provide significant absorption at the high velocity blue wing of the Ly α line, whereas the corresponding transit light curves exhibit an early ingress and extended egress features. With the same code, we also modelled the absorption at the position of the 10 830 Å line of the metastable helium, showing that it can be detected only for the farthest planet of the considered two, if the helium abundance is comparable to the solar value. [ABSTRACT FROM AUTHOR]

Published
2022
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174. Pathways to Earth-like atmospheres. Extreme ultraviolet (EUV)-powered escape of hydrogen-rich protoatmospheres.

Author

Lammer H, Kislyakova KG, Odert P, Leitzinger M, Schwarz R, Pilat-Lohinger E, Kulikov YN, Khodachenko ML, Güdel M, and Hanslmeier M

Subjects
Carbon Dioxide chemistry, Stars, Celestial, Steam, Atmosphere chemistry, Evolution, Planetary, Hydrogen chemistry, Ultraviolet Rays
Abstract

We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO2 and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N2-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star's EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets.

Published
2011
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175. Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

Author

Leitzinger M, Odert P, Kulikov YN, Lammer H, Wuchterl G, Penz T, Guarcello MG, Micela G, Khodachenko ML, Weingrill J, Hanslmeier A, Biernat HK, and Schneider J

Abstract

We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68REarth) and Kepler-10b (∼1.416REarth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a "Hot Neptune" nor a "Hot Uranus"-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects.

Published
2011
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