Energetic neutral atoms around HD 209458b: estimations of magnetospheric properties

Ekenbäck, A.; Holmström, M.; Wurz, P.; Grießmeier, J.-M.; Lammer, H.; Selsis, F.; Penz, T. (2010). Energetic neutral atoms around HD 209458b: estimations of magnetospheric properties. Astrophysical journal, 709(2), pp. 670-679. Institute of Physics Publishing IOP 10.1088/0004-637x/709/2/670

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HD 209458b is an exoplanet found to transit the disk of its parent star. Observations have shown a broad absorption signature about the Lyα stellar line during transit, suggesting the presence of a thick cloud of atomic hydrogen around the "hot Jupiter" HD 209458b. This work expands on an earlier work studying the production of energetic neutral atoms (ENAs) as a result of the interaction between the stellar wind and the exosphere. We present an improved flow model of HD 209458b and use stellar wind values similar to those in our solar system. We find that the ENA production is high enough to explain the observations, and we show that—using expected values for the stellar wind and exosphere—the spatial and velocity distributions of ENAs would give absorption in good agreement with the observations. We also study how the production of ENAs depends on the exospheric parameters and establish an upper limit for the obstacle standoff distance at approximately 4–10 planetary radii. Finally, we compare the results obtained for the obstacle standoff distance with existing exomagnetospheric models and show how the magnetic moment of HD 209458b can be estimated from ENA observations

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Wurz, Peter

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering

ISSN:

0004-637X

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

08 Jun 2021 16:15

Last Modified:

08 Jun 2021 16:15

Publisher DOI:

10.1088/0004-637x/709/2/670

BORIS DOI:

10.48350/154828

URI:

https://boris.unibe.ch/id/eprint/154828

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