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Title: STELLAR WIND INDUCED SOFT X-RAY EMISSION FROM CLOSE-IN EXOPLANETS

Abstract

In this Letter, we estimate the X-ray emission from close-in exoplanets. We show that the Solar/Stellar Wind Charge Exchange Mechanism (SWCX), which produces soft X-ray emission, is very effective for hot Jupiters. In this mechanism, X-ray photons are emitted as a result of the charge exchange between heavy ions in the solar wind and the atmospheric neutral particles. In the solar system, comets produce X-rays mostly through the SWCX mechanism, but it has also been shown to operate in the heliosphere, in the terrestrial magnetosheath, and on Mars, Venus, and the Moon. Since the number of emitted photons is proportional to the solar wind mass flux, this mechanism is not very effective for the solar system giants. Here we present a simple estimate of the X-ray emission intensity that can be produced by close-in extrasolar giant planets due to charge exchange with the heavy ions of the stellar wind. Using the example of HD 209458b, we show that this mechanism alone can be responsible for an X-ray emission of ≈10{sup 22} erg s{sup –1}, which is 10{sup 6} times stronger than the emission from the Jovian aurora. We discuss also the possibility of observing the predicted soft X-ray flux of hot Jupitersmore » and show that despite high emission intensities they are unobservable with current facilities.« less

Authors:
;  [1];  [2];  [3];  [4];  [5]
  1. Space Research Institute, Austrian Academy of Sciences, Graz (Austria)
  2. Argelander-Institut für Astronomie der Universität Bonn, Bonn (Germany)
  3. Department of Astrophysics, University of Vienna, Vienna (Austria)
  4. Swedish Institute of Space Physics, Kiruna (Sweden)
  5. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation)
Publication Date:
OSTI Identifier:
22364353
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AURORAE; CHARGE EXCHANGE; COMETS; HEAVY IONS; HELIOSPHERE; JUPITER PLANET; MAGNETOSHEATH; MARS PLANET; MASS; MOON; SOFT X RADIATION; SOLAR SYSTEM; SOLAR WIND; STARS; VENUS PLANET

Citation Formats

Kislyakova, K. G., Lammer, H., Fossati, L., Johnstone, C. P., Holmström, M., and Zaitsev, V. V., E-mail: kristina.kislyakova@oeaw.ac.at. STELLAR WIND INDUCED SOFT X-RAY EMISSION FROM CLOSE-IN EXOPLANETS. United States: N. p., 2015. Web. doi:10.1088/2041-8205/799/2/L15.
Kislyakova, K. G., Lammer, H., Fossati, L., Johnstone, C. P., Holmström, M., & Zaitsev, V. V., E-mail: kristina.kislyakova@oeaw.ac.at. STELLAR WIND INDUCED SOFT X-RAY EMISSION FROM CLOSE-IN EXOPLANETS. United States. doi:10.1088/2041-8205/799/2/L15.
Kislyakova, K. G., Lammer, H., Fossati, L., Johnstone, C. P., Holmström, M., and Zaitsev, V. V., E-mail: kristina.kislyakova@oeaw.ac.at. Fri . "STELLAR WIND INDUCED SOFT X-RAY EMISSION FROM CLOSE-IN EXOPLANETS". United States. doi:10.1088/2041-8205/799/2/L15.
@article{osti_22364353,
title = {STELLAR WIND INDUCED SOFT X-RAY EMISSION FROM CLOSE-IN EXOPLANETS},
author = {Kislyakova, K. G. and Lammer, H. and Fossati, L. and Johnstone, C. P. and Holmström, M. and Zaitsev, V. V., E-mail: kristina.kislyakova@oeaw.ac.at},
abstractNote = {In this Letter, we estimate the X-ray emission from close-in exoplanets. We show that the Solar/Stellar Wind Charge Exchange Mechanism (SWCX), which produces soft X-ray emission, is very effective for hot Jupiters. In this mechanism, X-ray photons are emitted as a result of the charge exchange between heavy ions in the solar wind and the atmospheric neutral particles. In the solar system, comets produce X-rays mostly through the SWCX mechanism, but it has also been shown to operate in the heliosphere, in the terrestrial magnetosheath, and on Mars, Venus, and the Moon. Since the number of emitted photons is proportional to the solar wind mass flux, this mechanism is not very effective for the solar system giants. Here we present a simple estimate of the X-ray emission intensity that can be produced by close-in extrasolar giant planets due to charge exchange with the heavy ions of the stellar wind. Using the example of HD 209458b, we show that this mechanism alone can be responsible for an X-ray emission of ≈10{sup 22} erg s{sup –1}, which is 10{sup 6} times stronger than the emission from the Jovian aurora. We discuss also the possibility of observing the predicted soft X-ray flux of hot Jupiters and show that despite high emission intensities they are unobservable with current facilities.},
doi = {10.1088/2041-8205/799/2/L15},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 799,
place = {United States},
year = {Fri Jan 30 00:00:00 EST 2015},
month = {Fri Jan 30 00:00:00 EST 2015}
}
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