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Characterization of the HD 219134 multi-planet system II. Stellar-wind sputtered exospheres in rocky planets b & c

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dc.contributor.author Vidotto, A. A
dc.contributor.author Lichtenegger, H
dc.contributor.author Fossati, L
dc.contributor.author Folsom, C. P
dc.contributor.author Wood, B. E
dc.contributor.author Murthy, J
dc.contributor.author Petit, P
dc.contributor.author Sreejith, A. G
dc.contributor.author Valyavin, G
dc.date.accessioned 2020-11-10T02:06:54Z
dc.date.available 2020-11-10T02:06:54Z
dc.date.issued 2018-12
dc.identifier.citation Monthly Notices of the Royal Astronomical Society, Vol. 481, No. 4, pp. 5296-5306 en_US
dc.identifier.issn 1365-2966
dc.identifier.uri http://prints.iiap.res.in/handle/2248/6711
dc.description Restricted Access © Royal Astronomical Society https://doi.org/10.1093/mnras/sty2130 en_US
dc.description.abstract We present a 3D study of the formation of refractory-rich exospheres around the rocky planets HD219134b and c. These exospheres are formed by surface particles that have been sputtered by the wind of the host star. The stellar wind properties are derived from magnetohydrodynamic simulations, which are driven by observationally-derived stellar magnetic field maps, and constrained by Ly-α observations of wind mass-loss rates, making this one of the most well-constrained model of winds of low-mass stars. The proximity of the planets to their host star implies a high flux of incident stellar wind particles, thus the sputtering process is sufficiently effective to build up relatively dense, refractory-rich exospheres. The sputtering releases refractory elements from the entire dayside surfaces of the planets, with elements such as O and Mg creating an extended neutral exosphere with densities larger than 10 cm−3, extending to several planetary radii. For planet ‘b’, the column density of O I along the line of sight reaches 1013 cm−2, with the highest values found ahead of its orbital motion. This asymmetry would create asymmetric transit profiles. To assess its observability, we use a ray tracing technique to compute the expected transit depth of the O I exosphere of planet ‘b’. We find that the transit depth in the O I 1302.2 Å line is 0.042 per cent, which is a small increase relative to the continuum transit (0.036 per cent). This implies that the sputtered exosphere of HD219134b is unlikely to be detectable with our current UV instruments. en_US
dc.language.iso en en_US
dc.publisher Oxford University Press on behalf of the Royal Astronomical Society en_US
dc.subject Planets and satellites: atmospheres en_US
dc.subject Stars: low-mass en_US
dc.subject Stars: planetary systems en_US
dc.subject Stars: individual: HD 219134 en_US
dc.subject Stars: winds en_US
dc.subject Outflows en_US
dc.title Characterization of the HD 219134 multi-planet system II. Stellar-wind sputtered exospheres in rocky planets b & c en_US
dc.type Article en_US


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