The study presents estimates of the atmospheric mass-loss rate for the planet WASP-195 b. The F-type star WASP-195 hosts a planet whose mass is only 0.104 that of Jupiter, yet their radii are comparable. The planet thus has a low mean density (ρ = 0.16± 0.06 g/cm3). To evaluate the atmospheric mass outflow, two approaches were applied: (1) an approximate relation corresponding to the energy-limited escape model, and (2) a method based on interpolation of results obtained from a grid of hydrodynamic upper-atmosphere models. The stellar XUV photon fluxes were estimated using an analytical relation linking FXUV and the chromospheric activity index <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${{\mathrm{log}R}^{\mathrm{^{\prime}}}}_{HK}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow> <mmultiscripts> <mrow> <mi mathvariant="normal">log</mi> <mi>R</mi> </mrow> <mrow /> <mmultiscripts> <mrow /> <mrow /> <mo>′</mo> </mmultiscripts> </mmultiscripts> </mrow> <mrow> <mi mathvariant="italic">HK</mi> </mrow> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>. The obtained estimates of the atmospheric mass-loss rate Ṁ were compared as a function of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${{\mathrm{log}R}^{\mathrm{^{\prime}}}}_{HK}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow> <mmultiscripts> <mrow> <mi mathvariant="normal">log</mi> <mi>R</mi> </mrow> <mrow /> <mmultiscripts> <mrow /> <mrow /> <mo>′</mo> </mmultiscripts> </mmultiscripts> </mrow> <mrow> <mi mathvariant="italic">HK</mi> </mrow> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation> variations for both the energy-limited and hydrodynamic escape models. The calculations show that the atmospheric mass loss of the exoplanet is significant even in the case of low chromospheric activity of the host star. The maximum value of Ṁ may reach 7.3·1011 g/s (according to the hydrodynamic model under conditions of high stellar activity).

Atmospheric Mass Loss of Planet WASP-195b

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发表日期：

2025年9月1日

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I. S. Savanov,
E. S. Dmitrienko

摘要

The study presents estimates of the atmospheric mass-loss rate for the planet WASP-195 b. The F-type star WASP-195 hosts a planet whose mass is only 0.104 that of Jupiter, yet their radii are comparable. The planet thus has a low mean density (ρ = 0.16± 0.06 g/cm³). To evaluate the atmospheric mass outflow, two approaches were applied: (1) an approximate relation corresponding to the energy-limited escape model, and (2) a method based on interpolation of results obtained from a grid of hydrodynamic upper-atmosphere models. The stellar XUV photon fluxes were estimated using an analytical relation linking F_XUV and the chromospheric activity index ${{\mathrm{log}R}^{\mathrm{^{\prime}}}}_{HK}$ ${\log R}^{^{'}}_{HK}$ . The obtained estimates of the atmospheric mass-loss rate Ṁ were compared as a function of ${{\mathrm{log}R}^{\mathrm{^{\prime}}}}_{HK}$ ${\log R}^{^{'}}_{HK}$ variations for both the energy-limited and hydrodynamic escape models. The calculations show that the atmospheric mass loss of the exoplanet is significant even in the case of low chromospheric activity of the host star. The maximum value of Ṁ may reach 7.3·10¹¹ g/s (according to the hydrodynamic model under conditions of high stellar activity).