MOVES III. Simultaneous X-ray and ultraviolet observations unveiling the variable environment of the hot Jupiter HD 189733b

Bourrier, V.; Wheatley, P. J.; Étangs, A. Lecavelier des; King, George W.; Louden, Tom; Ehrenreich, D.; Farès, R.; Helling, Christiane; Llama, Joe; Jardine, M.; Vidotto, A. A.

doi:10.1093/mnras/staa256

Cited by 36 publications

(41 citation statements)

References 131 publications

(157 reference statements)

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“…We explain the night-to-night variations in the He I absorption signal as a consequence of the stellar surface geometry (the presence of quiescent and active regions during planetary transit) and not due to stellar variations, such as interaction with stellar wind or flares, or changes in the X-ray and EUV (hereafter XUV) irradiation. Viceversa, variation in the stellar wind and XUV spectrum could instead influence the density of neutral hydrogen resulting in a temporal variation in the in-transit Ly-α signal (Lecavelier Des Etangs et al 2012;Bourrier et al 2020). Our feelings are corroborated by the detection of Hα in emission during transit 1 and 3 and not in absorption, as expected by interaction with stellar wind or by variations in the XUV spectrum.…”

Section: Discussionsupporting

confidence: 80%

The GAPS programme at TNG

Guilluy

Andretta

Borsa

et al. 2020

A&A

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Context. Exoplanets orbiting very close to their parent star are strongly irradiated. This can lead the upper atmospheric layers to expand and evaporate into space. The metastable helium (He I) triplet at 1083.3 nm has recently been shown to be a powerful diagnostic to probe extended and escaping exoplanetary atmospheres. Aims. We perform high-resolution transmission spectroscopy of the transiting hot Jupiter HD 189733 b with the GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo, taking advantage of the simultaneous optical+near infrared spectral coverage to detect He I in the planet’s extended atmosphere and to gauge the impact of stellar magnetic activity on the planetary absorption signal. Methods. Observations were performed during five transit events of HD 189733 b. By comparison of the in-transit and out-of-transit GIANO-B observations, we computed high-resolution transmission spectra. We then used them to perform equivalent width measurements and carry out light-curves analyses in order to consistently gauge the excess in-transit absorption in correspondence with the He I triplet. Results. We spectrally resolve the He I triplet and detect an absorption signal during all five transits. The mean in-transit absorption depth amounts to 0.75 ± 0.03% (25σ) in the core of the strongest helium triplet component. We detect night-to-night variations in the He I absorption signal likely due to the transit events occurring in the presence of stellar surface inhomogeneities. We evaluate the impact of stellar-activity pseudo-signals on the true planetary absorption using a comparative analysis of the He I 1083.3 nm (in the near-infrared) and the Hα (in the visible) lines. Using a 3D atmospheric code, we interpret the time series of the He I absorption lines in the three nights not affected by stellar contamination, which exhibit a mean in-transit absorption depth of 0.77 ± 0.04% (19σ) in full agreement with the one derived from the full dataset. In agreement with previous results, our simulations suggest that the helium layers only fill part of the Roche lobe. Observations can be explained with a thermosphere heated to ~12 000 K, expanding up to ~1.2 planetary radii, and losing ~1 g s−1 of metastable helium. Conclusions. Our results reinforce the importance of simultaneous optical plus near infrared monitoring when performing high-resolution transmission spectroscopy of the extended and escaping atmospheres of hot planets in the presence of stellar activity.

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Section: Discussionsupporting

confidence: 80%

The GAPS programme at TNG

Guilluy

Andretta

Borsa

et al. 2020

A&A

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“…Opaque region sizes measured at other wavelengths (e.g. Ly 𝛼: Lecavelier des Bourrier et al 2020) have indicated there are detectable levels of escape of atmospheric material beyond this point. This and other such signals are typically observed in specific lines of interest and not in broadband measurements such as those presented here.…”

Section: Discussionmentioning

confidence: 99%

“…The transit depths at Ly 𝛼 wavelengths of up to 15 per cent have been observed to be variable (Lecavelier des Etangs et al 2012). Additionally, Ben-Jaffel & Ballester (2013) measured a 6.4 per cent transit in O , and there is a time-variable absorption signature in the Si line that could arise from a bow-shock formed ahead of the planet in its orbit (Bourrier et al , 2020. In X-rays Poppenhaeger et al (2013) presented evidence of the X-ray transit possibly being as deep as 8 per cent.…”

Section: The Hd 189733 Systemmentioning

confidence: 98%

“…The planet is also one of an increasing number to have a helium excess measured in the metastable 10830 Å triplet (Salz et al 2018;Guilluy et al 2020). HD 189733b's atmosphere has also been studied at shorter wavelengths, with Ly 𝛼 transit observations showing that H is moving beyond the Roche lobe and escaping the atmosphere (Lecavelier Des Etangs et al 2010;Lecavelier des Etangs et al 2012;Bourrier et al , 2020. The transit depths at Ly 𝛼 wavelengths of up to 15 per cent have been observed to be variable (Lecavelier des Etangs et al 2012).…”

Section: The Hd 189733 Systemmentioning

confidence: 99%

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The near-UV transit of HD 189733b with the XMM–Newton optical monitor

King

Corrales

Wheatley

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present analysis of XMM-Newton Optical Monitor observations in the near-ultraviolet of HD 189733, covering twenty primary transits of its hot Jupiter planet. The transit is clearly detected with both the UVW2 and UVM2 filters, and our fits to the data reveal transit depths in agreement with that observed optically. The measured depths correspond to radii of $1.05{9}^{+0.0{46}}_{-0.0{50}}$ and $0.9{4}^{+0.15}_{-0.17}$ times the optically-measured radius in the UVW2 and UVM2 bandpasses, respectively. We also find no statistically significant variation in the transit depth across the 8 year baseline of the observations. We rule out extended broadband absorption towards or beyond the Roche lobe at the wavelengths investigated, although observations with higher spectral resolution are required to determine if absorption out to those distances from the planet is present in individual near-UV lines.

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“…The fast-evolving activity of the stellar surface of HD 189733 has been studied and modeled multiple times in the past (e.g., Boisse et al 2009;Lanza et al 2011;Fares et al 2017) because in many ways, it affects the measurement of the system parameters, including atmospheric composition and planetary environment conditions (Pont et al 2007;Sing et al 2011;Bourrier et al 2020). The stellar magnetic field of HD 189733 was also analyzed in the SPIRou data set.…”

Section: Discussionmentioning

confidence: 99%

Early science with SPIRou: near-infrared radial velocity and spectropolarimetry of the planet-hosting star HD 189733

Moutou

Dalal

Donati

et al. 2020

A&A

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SPIRou is the newest spectropolarimeter and high-precision velocimeter that has recently been installed at the Canada-France-Hawaii Telescope on Maunakea, Hawaii. It operates in the near-infrared and simultaneously covers the 0.98–2.35 μm domain at high spectral resolution. SPIRou is optimized for exoplanet search and characterization with the radial-velocity technique, and for polarization measurements in stellar lines and subsequent magnetic field studies. The host of the transiting hot Jupiter HD 189733 b has been observed during early science runs. We present the first near-infrared spectropolarimetric observations of the planet-hosting star as well as the stellar radial velocities as measured by SPIRou throughout the planetary orbit and two transit sequences. The planetary orbit and Rossiter-McLaughlin anomaly are both investigated and modeled. The orbital parameters and obliquity are all compatible with the values found in the optical. The obtained radial-velocity precision is compatible with about twice the photon-noise estimates for a K2 star under these conditions. The additional scatter around the orbit, of about 8 m s−1, agrees with previous results that showed that the activity-induced scatter is the dominant factor. We analyzed the polarimetric signal, Zeeman broadening, and chromospheric activity tracers such as the 1083nm HeI and the 1282nm Paβ lines to investigate stellar activity. First estimates of the average unsigned magnetic flux from the Zeeman broadening of the FeI lines give a magnetic flux of 290 ± 58 G, and the large-scale longitudinal field shows typical values of a few Gauss. These observations illustrate the potential of SPIRou for exoplanet characterization and magnetic and stellar activity studies.

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MOVES III. Simultaneous X-ray and ultraviolet observations unveiling the variable environment of the hot Jupiter HD 189733b

Cited by 36 publications

References 131 publications

The GAPS programme at TNG

The GAPS programme at TNG

The near-UV transit of HD 189733b with the XMM–Newton optical monitor

Early science with SPIRou: near-infrared radial velocity and spectropolarimetry of the planet-hosting star HD 189733

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