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/ P. Cubillos [et al.] // Mon. Not. Roy. Astron. Soc. - 2017. - Vol. 466, Is. 2. - P1868-1879, DOI 10.1093/mnras/stw3103. - Cited References:107. - We thank contributors to SCIPY, MATPLOTLIB (Hunter 2007), the PYTHON programming language, and contributors to the free and open-source community. We thank the anonymous referee for comments that significantly improved the quality of the paper. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org and the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. We acknowledge the Austrian Forschungsforderungsgesellschaft FFG projects 'RASEN' P847963 and 'TAPAS4CHEOPS' P853993, the Austrian Science Fund (FWF) National Research Network projects S11607-N16 and S11604-N16, and the FWF project P27256-N27. NVE acknowledges support by the Russian Foundation for Basic Research grant no. 15-05-00879-a and no. 16-52-14006 ANF-a. . - ISSN 0035-8711. - ISSN 1365-2966РУБ Astronomy & Astrophysics

Аннотация: We present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to M-p < 30M(circle plus)). For each planet, we compute the restricted Jeans escape parameter, Lambda, for a hydrogen atom evaluated at the planetary mass, radius, and equilibrium temperature. Values of Lambda less than or similar to 20 suggest extremely high mass-loss rates. We identify 27 planets (out of 167) that are simultaneously consistent with hydrogen-dominated atmospheres and are expected to exhibit extreme mass-loss rates. We further estimate the mass-loss rates (L-hy) of these planets with tailored atmospheric hydrodynamic models. We compare L-hy to the energy-limited (maximum-possible high-energy driven) mass-loss rates. We confirm that 25 planets (15 per cent of the sample) exhibit extremely high mass-loss rates (L-hy > 0.1M(circle plus) Gyr(-1)), well in excess of the energy-limited mass-loss rates. This constitutes a contradiction, since the hydrogen envelopes cannot be retained given the high mass-loss rates. We hypothesize that these planets are not truly under such high mass-loss rates. Instead, either hydrodynamic models overestimate the mass-loss rates, transit-timing-variation measurements underestimate the planetary masses, optical transit observations overestimate the planetary radii (due to high-altitude clouds), or Neptunes have consistently higher albedos than Jupiter planets. We conclude that at least one of these established estimations/ techniques is consistently producing biased values for Neptune planets. Such an important fraction of exoplanets with misinterpreted parameters can significantly bias our view of populations studies, like the observed mass-radius distribution of exoplanets for example.

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

Доп.точки доступа:
Cubillos, Patricio; Erkaev, N.V.; Еркаев, Николай Васильевич; Juvan, Ines; Fossati, Luca; Johnstone, Colin P.; Lammer, Helmut; Lendl, Monika; Odert, Petra; Kislyakova, Kristina G.; Austrian Forschungsforderungsgesellschaft FFG [P847963, P853993]; Austrian Science Fund (FWF) National Research Network projects [S11607-N16, S11604-N16]; FWF [P27256-N27]; Russian Foundation for Basic Research [15-05-00879-a, 16-52-14006 ANF-a]