Neptune-like planets low-density overabundance Virtual Observatory Resource

Authors
  1. Cubillos P.
  2. Erkaev N.V.
  3. Juvan I.
  4. Fossati L.
  5. Johnstone C.P.
  6. Lammer H.,Lendl M.
  7. Odert P.
  8. Kislyakova K.G.
  9. Published by
    CDS
Abstract

We present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to M_p_<30M_{Earth}_). 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}<=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_{Earth}_/Gyr), 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.

Keywords
  1. Multiple stars
  2. Exoplanets
  3. Galaxy classification systems
  4. Stellar mass loss
Bibliographic source Bibcode
2017MNRAS.466.1868C
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/466/1868
IVOA Identifier IVOID
ivo://CDS.VizieR/J/MNRAS/466/1868
Document Object Identifer DOI

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/466/1868
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/466/1868
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/466/1868
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https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/466/1868/tablea1?
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History

2019-11-27T14:22:05Z
Resource record created
2019-11-27T14:22:05Z
Created
2020-04-08T08:28:16Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr