TY - JOUR
T1 - MOVES III. Simultaneous X-ray and ultraviolet observations unveiling the variable environment of the hot Jupiter HD189733b
AU - Bourrier, V.
AU - Wheatley, P. J.
AU - Lecavelier Des Etangs, A.
AU - King, G.
AU - Louden, T.
AU - Ehrenreich, D.
AU - Fares, R.
AU - Helling, Ch
AU - Llama, J.
AU - Jardine, M. M.
AU - Vidotto, A. A.
N1 - Funding Information:
We thank the referee for their attentive review of our paper. We thank D.K. Sing for his help and insights into the investigation of the HST jitter. VB acknowledges support by the Swiss National Science Foundation (SNSF) in the frame of the National Centre for Competence in Research 'PlanetS', and has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project Four Aces; grant agreement No. 724427). PJW, GK, and TL acknowledge support from the UK Science and Technology Facilities Council (STFC) under the consolidated grants ST/L000733/1 and ST/P000495/1. ALE acknowledges support from the French Centre national d'Etude Spatiales (CNES) and the French Agence Nationale de la Recherche (ANR), under programme ANR-12-BS05-0012 Exo-Atmos. AAV acknowledges funding from the Irish Research Council. This work is based on observations made with the National Aeronautics and Space Administration / European Space Agency (NASA/ESA) Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research hasmade use of data obtained from NASA's Swift satellite. This work has made use of data from the ESAmission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, ht tps://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Publisher Copyright:
© 2020 The Author(s).
PY - 2020/3/1
Y1 - 2020/3/1
N2 - In this third paper of the MOVES (Multiwavelength Observations of an eVaporating Exoplanet and its Star) programme, we combine Hubble Space Telescope far-ultraviolet (FUV) observations with XMM-Newton/Swift X-ray observations to measure the emission of HD189733 in various FUV lines, and its soft X-ray spectrum. Based on these measurements we characterize the interstellar medium towards HD189733 and derive semisynthetic XUV spectra of the star, which are used to study the evolution of its high-energy emission at five different epochs. Two flares from HD189733 are observed, but we propose that the long-term variations in its spectral energy distribution have the most important consequences for the environment of HD189733b. Reduced coronal and wind activity could favour the formation of a dense population of Si2+ atoms in a bow-shock ahead of the planet, responsible for preand in-transit absorption measured in the first two epochs. In-transit absorption signatures are detected in the Lyman α line in the second, third, and fifth epochs, which could arise from the extended planetary thermosphere and a tail of stellar wind protons neutralized via chargeexchange with the planetary exosphere. We propose that increases in the X-ray irradiation of the planet, and decreases in its EUV irradiation causing lower photoionization rates of neutral hydrogen, favour the detection of these signatures by sustaining larger densities of H0 atoms in the upper atmosphere and boosting charge-exchanges with the stellar wind. Deeper and broader absorption signatures in the last epoch suggest that the planet entered a different evaporation regime, providing clues as to the link between stellar activity and the structure of the planetary environment.
AB - In this third paper of the MOVES (Multiwavelength Observations of an eVaporating Exoplanet and its Star) programme, we combine Hubble Space Telescope far-ultraviolet (FUV) observations with XMM-Newton/Swift X-ray observations to measure the emission of HD189733 in various FUV lines, and its soft X-ray spectrum. Based on these measurements we characterize the interstellar medium towards HD189733 and derive semisynthetic XUV spectra of the star, which are used to study the evolution of its high-energy emission at five different epochs. Two flares from HD189733 are observed, but we propose that the long-term variations in its spectral energy distribution have the most important consequences for the environment of HD189733b. Reduced coronal and wind activity could favour the formation of a dense population of Si2+ atoms in a bow-shock ahead of the planet, responsible for preand in-transit absorption measured in the first two epochs. In-transit absorption signatures are detected in the Lyman α line in the second, third, and fifth epochs, which could arise from the extended planetary thermosphere and a tail of stellar wind protons neutralized via chargeexchange with the planetary exosphere. We propose that increases in the X-ray irradiation of the planet, and decreases in its EUV irradiation causing lower photoionization rates of neutral hydrogen, favour the detection of these signatures by sustaining larger densities of H0 atoms in the upper atmosphere and boosting charge-exchanges with the stellar wind. Deeper and broader absorption signatures in the last epoch suggest that the planet entered a different evaporation regime, providing clues as to the link between stellar activity and the structure of the planetary environment.
KW - ISM: clouds
KW - Planet-star interactions
KW - Planets and satellites: individual: HD189733b
KW - Stars: chromospheres, coronae
KW - Stars: individual: HD189733
KW - Techniques: spectroscopic
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U2 - 10.1093/mnras/staa256
DO - 10.1093/mnras/staa256
M3 - Article
AN - SCOPUS:85090217713
SN - 0035-8711
VL - 493
SP - 559
EP - 579
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -