A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

Esteves, Lisa J.; Mooij, Ernst de; Jayawardhana, Ray; Watson, Chris; Kok, Remco de

doi:10.3847/1538-3881/aa7133

Cited by 93 publications

(93 citation statements)

References 55 publications

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“…Similarly to Gibson et al (2019), we applied the SysRem algorithm (Tamuz et al 2005) which was first demonstrated on high-resolution spectroscopy by Birkby et al (2013), and has since become a standard technique (e.g. Birkby et al 2017;Esteves et al 2017;Nugroho et al 2017;Deibert et al 2019). First, we apply SysRem to each order in the standard way, and determine a model representation of the 2D data array (time vs wavelength) as an outer product of two column vectors, before subtracting from the data and determining the next SysRem iteration.…”

Section: Discussionmentioning

confidence: 99%

Detection of Fe i in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy

Gibson

Merritt

Nugroho

et al. 2020

Monthly Notices of the Royal Astronomical Society

159

222

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High-resolution Doppler-resolved spectroscopy has opened up a new window into the atmospheres of both transiting and non-transiting exoplanets. Here, we present VLT/UVES observations of a transit of WASP-121b, an 'ultra-hot' Jupiter previously found to exhibit a temperature inversion and detections of multiple species at optical wavelengths. We present initial results using the blue arm of UVES (≈3700 -5000Å), recovering a clear signal of neutral Fe in the planet's atmosphere at >8 σ, which could contribute to (or even fully explain) the temperature inversion in the stratosphere. However, using standard cross-correlation methods, it is difficult to extract physical parameters such as temperature and abundances. Recent pioneering efforts have sought to develop likelihood 'mappings' that can be used to directly fit models to high-resolution datasets. We introduce a new framework that directly computes the likelihood of the model fit to the data, and can be used to explore the posterior distribution of parameterised model atmospheres via MCMC techniques. Our method also recovers the physical extent of the atmosphere, as well as account for time-and wavelength-dependent uncertainties. We measure a temperature of 3710 +490 −510 K, indicating a higher temperature in the upper atmosphere when compared to low-resolution observations. We also show that the Fe i signal is physically separated from the exospheric Fe ii. However, the temperature measurements are highly degenerate with aerosol properties; detection of additional species, using more sophisticated atmospheric models, or combining these methods with low-resolution spectra should help break these degeneracies.

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Section: Discussionmentioning

confidence: 99%

Detection of Fe i in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy

Gibson

Merritt

Nugroho

et al. 2020

Monthly Notices of the Royal Astronomical Society

159

222

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“…Birkby et al 2013Birkby et al , 2017Esteves et al 2017). Each wavelength bin (4100 wavelength bin per order on average) is treated as a "light-curve" consisting of 52 frames (including the frames when WASP-33 b in the secondary eclipse phase).…”

Section: Removal Of Telluric and Stellar Absorption Linesmentioning

confidence: 99%

“…Recently, direct detection of molecular signature in exoplanet atmosphere using high-dispersion spectroscopy is one of the most widespread approach to the attempt of exoplanet characterization (e.g Snellen et al 2010;Crossfield et al 2011;Birkby et al 2013;de Kok et al 2013;Hoeijmakers et al 2015;Schwarz et al 2015;Birkby et al 2017;Esteves et al 2017). Unlike low-dispersion spectroscopy, high-dispersion spectroscopy can resolve molecular bands into individual absorption lines.…”

Section: Introductionmentioning

confidence: 99%

High-resolution Spectroscopic Detection of TiO and a Stratosphere in the Day-side of WASP-33b

et al. 2017

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We report high-resolution spectroscopic detection of TiO molecular signature in the day-side spectra of WASP-33 b, the second hottest known hot Jupiter. We used High-Dispersion Spectrograph (HDS; R ∼ 165,000) in the wavelength range of 0.62 -0.88 µm with the Subaru telescope to obtain the day-side spectra of WASP-33 b. We suppress and correct the systematic effects of the instrument, the telluric and stellar lines by using SYSREM algorithm after the selection of good orders based on Barnard star and other M-type stars. We detect a 4.8-σ signal at an orbital velocity of K p = +237.5 −1 , which agree with the derived values from the previous analysis of primary transit. Our detection with the temperature inversion model implies the existence of stratosphere in its atmosphere, however, we were unable to constrain the volume-mixing ratio of the detected TiO. We also measure the stellar radial velocity and use it to obtain a more stringent constraint on the orbital velocity, K p = 239.0Our results demonstrate that high-dispersion spectroscopy is a powerful tool to characterize the atmosphere of an exoplanet, even in the optical wavelength range, and show a promising potential in using and developing similar techniques with high-dispersion spectrograph on current 10m-class and future extremely large telescopes.

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“…However, the discovery of super-Earths like 55 Cancri e that have hydrogenrich envelops (e.g. Tsiaras et al 2016;Esteves et al 2017) and effective temperatures above ∼ 2000 K (Demory et al 2016) have raised new questions. This is because XUV atmospheric evaporation models predict the destruction of primordial atmospheres in million year timescales for planets with initial masses of super-Earths (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we apply our model to 55 Cancri e because of its well constrained mass and radius (Crida et al 2018), its measured surface temperature distribution (Demory et al 2016) (which is also indicative of a synchronous rotation), and spectroscopic studies which are consistent with it being a terran body (Ridden-Harper et al 2016) hosting a hydrogen-rich atmosphere (Tsiaras et al 2016;Esteves et al 2017). CoRoT-7b being similar in mass and radius (Barros et al 2014) to 55 Cancri e but not being compatible with having an envelop (Guenther et al 2011;Kubyshkina et al 2018a) has been used in order to act as a control planet.…”

Section: Introductionmentioning

confidence: 99%

Hot Super-Earths with Hydrogen Atmospheres: A Model Explaining Their Paradoxical Existence

Modirrousta-Galian

Locci

Tinetti

et al. 2020

ApJ

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In this paper we propose a new mechanism that could explain the survival of hydrogen atmospheres on some hot super-Earths. We argue that on close-orbiting tidally-locked super-Earths the tidal forces with the orbital and rotational centrifugal forces can partially confine the atmosphere on the nightside. Assuming a super terran body with an atmosphere dominated by volcanic species and a large hydrogen component, the heavier molecules can be shown to be confined within latitudes of 80 • whilst the volatile hydrogen is not. Because of this disparity the hydrogen has to slowly diffuse out into the dayside where XUV irradiation destroys it. For this mechanism to take effect it is necessary for the exoplanet to become tidally locked before losing the totality of its hydrogen envelop. Consequently, for super-Earths with this proposed configuration it is possible to solve the tidal-locking and mass-loss timescales in order to constrain their formation 'birth' masses. Our model predicts that 55 Cancri e formed with a day-length between approximately 17 − 18.5 hours and an initial mass less than ∼ 12M ⊕ hence allowing it to become tidally locked before the complete destruction of its atmosphere. For comparison, CoRoT-7b, an exoplanet with very similar properties to 55 Cancri e but lacking an atmosphere, formed with a day-length significantly different from ∼ 20.5 hours whilst also having an initial mass smaller than ∼ 9M ⊕ .

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A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

Cited by 93 publications

References 55 publications

Detection of Fe i in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy

Detection of Fe i in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy

High-resolution Spectroscopic Detection of TiO and a Stratosphere in the Day-side of WASP-33b

Hot Super-Earths with Hydrogen Atmospheres: A Model Explaining Their Paradoxical Existence

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