Discovery of Water at High Spectral Resolution in the Atmosphere of 51 Peg b

Birkby, Jayne; Kok, Remco de; Brogi, Matteo; Schwarz, H.; Snellen, I. A. G.

doi:10.3847/1538-3881/aa5c87

Cited by 178 publications

(250 citation statements)

References 86 publications

(197 reference statements)

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“…the chemical composition of brown dwarfs (see Allard et al 1997;Helling & Casewell 2014 and references in these reviews) and exoplanets (e.g. Désert et al 2008;Grillmair et al 2008;de Kok et al 2013;Kreidberg et al 2014;Fraine et al 2014;Birkby et al 2017). We can also revisit the long-standing question of what drives the mass loss of oxygen-rich Asymptotic Giant Branch (AGB) stars (Gail & Sedlmayr 1998;Woitke 2006;Höfner & Andersen 2007;Golriz et al 2014;Gail et al 2016;Decin et al 2017), including the problem of seed particle formation and the search for the first condensate in space (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium chemistry down to 100 K

Woitke

Helling

Hunter

et al. 2018

A&A

206

234

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We introduce a fast and versatile computer code, GGchem, to determine the chemical composition of gases in thermo-chemical equilibrium down to 100 K, with or without equilibrium condensation. We review the data for molecular equilibrium constants, k p (T ), from several sources and discuss which functional fits are most suitable for low temperatures. We benchmark our results against another chemical equilibrium code. We collect Gibbs free energies, ∆G• − f , for about 200 solid and liquid species from the NIST-JANAF database and the geophysical database SUPCRTBL. We discuss the condensation sequence of the elements with solar abundances in phase equilibrium down to 100 K. Once the major magnesium silicates Mg 2 SiO 4 [s] and MgSiO 3 [s] have formed, the dust/gas mass ratio jumps to a value of about 0.0045 which is significantly lower than the often assumed value of 0.01. Silicate condensation is found to increase the carbon/oxygen ratio (C/O) in the gas from its solar value of ∼ 0.55 up to ∼ 0.71, and, by the additional intake of water and hydroxyl into the solid matrix, the formation of phyllosilicates at temperatures below ∼ 400 K increases the gaseous C/O further to about 0.83. Metallic tungsten (W) is the first condensate found to become thermodynamically stable around 1600 − 2200 K (depending on pressure), several hundreds of Kelvin before subsequent materials like zirconium dioxide (ZrO 2 ) or corundum (Al 2 O 3 ) can condense. We briefly discuss whether tungsten, despite its low abundance of ∼ 2 × 10 −7 times the silicon abundance, could provide the first seed particles for astrophysical dust formation. The GGchem code is publicly available at https://github.com/pw31/GGchem.

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Section: Introductionmentioning

confidence: 99%

Equilibrium chemistry down to 100 K

Woitke

Helling

Hunter

et al. 2018

A&A

206

234

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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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“…These observations have detected both absorption in the thermal emission spectrum of the planet (e.g. Birkby et al 2017), and absorption in transmission spectra (i.e. during transit) (e.g.…”

Section: Resultsmentioning

confidence: 99%

Exocomet orbit fitting: accelerating coma absorption during transits of β Pictoris

Kennedy

2018

Monthly Notices of the Royal Astronomical Society

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Comets are a remarkable feature in our night sky, visible on their passage through the inner Solar system as the Sun's energy sublimates ices and liberates surface material, generating beautiful comae, dust, and ion tails. Comets are also thought to orbit other stars, and are the most promising interpretation of sporadic absorption features (i.e. transits) seen in spectra of stars such as β Pictoris and 49 Ceti. These "exocomets" are thought to form and evolve in the same way as in the Solar system, and as in the Solar system we may gain insight into their origins by deriving their orbits. In the case of β Pictoris, orbits have been estimated indirectly, using the radial velocity of the absorption features coupled with a physical evaporation model to estimate the stellocentric distance at transit d tr . Here, we note that the inferred d tr imply that some absorption signatures should accelerate over several hours, and show that this acceleration is indeed seen in HARPS spectra. This new constraint means that orbital characteristics can be obtained directly, and the pericentre distance and longitude constrained when parabolic orbits are assumed. The results from fitting orbits to 12 accelerating features, and a handful of non-accelerating ones, are in broad agreement with previous estimates based on an evaporation model, thereby providing some validation of the exocomet hypothesis. A prediction of the evaporation model, that coma absorption is deeper for more distant transits, is also seen here.

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Discovery of Water at High Spectral Resolution in the Atmosphere of 51 Peg b

Cited by 178 publications

References 86 publications

Equilibrium chemistry down to 100 K

Equilibrium chemistry down to 100 K

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

Exocomet orbit fitting: accelerating coma absorption during transits of β Pictoris

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