Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol T OTO line list

Dilovan B. Serindag; Stevanus K. Nugroho; Paul Mollière; Ernst J.W. De Mooij; Neale P. Gibson; Ignas A.G. Snellen

doi:10.1051/0004-6361/202039135

Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol T OTO line list

Dilovan B. Serindag, Stevanus K. Nugroho, Paul Mollière, Ernst J.W. De Mooij, Neale P. Gibson, Ignas A.G. Snellen

Research output: Contribution to journal › Article › peer-review

25 Citations (Scopus)

Abstract

Context. Efficient absorption of stellar ultraviolet and visible radiation by TiO and VO is predicted to drive temperature inversions in the upper atmospheres of hot Jupiters. However, very few inversions or detections of TiO or VO have been reported, and results are often contradictory.

Aims. Using the improved ExoMol TOTO line list, we searched for TiO emission in the dayside spectrum ofWASP-33b using the same data in which the molecule was previously detected with an older line list at 4.8σ. We intended to confirm the molecular detection and quantify the signal improvement offered by the ExoMol TOTO line list.

Methods. Data from the High Dispersion Spectrograph on the Subaru Telescope was extracted and reduced in an identical manner to the previous study. Stellar and telluric contamination were then removed. High-resolution TiO emission models of WASP-33b were created that spanned a range of molecular abundances using the radiative transfer code petitRADTRANS, and were subsequently cross-correlated with the data.

Results. We measure a 4.3σ TiO emission signature using the ExoMol TOTO models, corresponding to a WASP-33b orbital velocity semi-amplitude of Kp=252.9-5.3+5.0 km s-1 and a system velocity of vsys=-23.0-4.6+4.7 km s-1. Injection-recovery tests using models based on the new and earlier line lists indicate that if the new models provide a perfect match to the planet spectrum, the significance of the TiO detection should have increased by a factor of 2.

Conclusions. Although the TiO signal we find is statistically significant, comparison with previous works makes our result too ambiguous to claim a clear-cut detection. Unexpectedly, the new ExoMol TOTO models provide a weaker signal than that found previously, which is offset in Kp-vsys space. This sheds some doubt on both detections, especially in light of a recently published TiO non-detection using a different dataset.

Original language	English
Article number	A90
Journal	Astronomy and Astrophysics
Volume	645
DOIs	https://doi.org/10.1051/0004-6361/202039135
Publication status	Published - 01 Jan 2021

Bibliographical note

Funding Information:
cA knolw edgements. D.B.S., P.M., and I.A.G.S. acknowledge support from the European Research Council under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 694513. S.K.N. would like to acknowledge support from UK Science Technology and Facility Council grant ST/P000312/1. P.M. acknowledges support from the European Research Council under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 832428. N.P.G. gratefully acknowledges support from Science Foundation Ireland and the Royal Society in the form of a University Research Fellowship.

Publisher Copyright:
© 2021 ESO.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

Planets and satellites: Atmospheres
Planets and satellites: Composition
Planets and satellites: Individual: WASP-33b
Techniques: Spectroscopic

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/202039135Licence: Unspecified

Cite this

@article{642b356a23e14a94bd6a090b7e4be2dd,

title = "Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol T OTO line list",

abstract = "Context. Efficient absorption of stellar ultraviolet and visible radiation by TiO and VO is predicted to drive temperature inversions in the upper atmospheres of hot Jupiters. However, very few inversions or detections of TiO or VO have been reported, and results are often contradictory. Aims. Using the improved ExoMol TOTO line list, we searched for TiO emission in the dayside spectrum ofWASP-33b using the same data in which the molecule was previously detected with an older line list at 4.8σ. We intended to confirm the molecular detection and quantify the signal improvement offered by the ExoMol TOTO line list. Methods. Data from the High Dispersion Spectrograph on the Subaru Telescope was extracted and reduced in an identical manner to the previous study. Stellar and telluric contamination were then removed. High-resolution TiO emission models of WASP-33b were created that spanned a range of molecular abundances using the radiative transfer code petitRADTRANS, and were subsequently cross-correlated with the data. Results. We measure a 4.3σ TiO emission signature using the ExoMol TOTO models, corresponding to a WASP-33b orbital velocity semi-amplitude of Kp=252.9-5.3+5.0 km s-1 and a system velocity of vsys=-23.0-4.6+4.7 km s-1. Injection-recovery tests using models based on the new and earlier line lists indicate that if the new models provide a perfect match to the planet spectrum, the significance of the TiO detection should have increased by a factor of 2.Conclusions. Although the TiO signal we find is statistically significant, comparison with previous works makes our result too ambiguous to claim a clear-cut detection. Unexpectedly, the new ExoMol TOTO models provide a weaker signal than that found previously, which is offset in Kp-vsys space. This sheds some doubt on both detections, especially in light of a recently published TiO non-detection using a different dataset. ",

keywords = "Planets and satellites: Atmospheres, Planets and satellites: Composition, Planets and satellites: Individual: WASP-33b, Techniques: Spectroscopic",

author = "Serindag, {Dilovan B.} and Nugroho, {Stevanus K.} and Paul Molli{\`e}re and {De Mooij}, {Ernst J.W.} and Gibson, {Neale P.} and Snellen, {Ignas A.G.}",

note = "Funding Information: cA knolw edgements. D.B.S., P.M., and I.A.G.S. acknowledge support from the European Research Council under the European Union{\textquoteright}s Horizon 2020 research and innovation program under grant agreement No. 694513. S.K.N. would like to acknowledge support from UK Science Technology and Facility Council grant ST/P000312/1. P.M. acknowledges support from the European Research Council under the European Union{\textquoteright}s Horizon 2020 research and innovation program under grant agreement No. 832428. N.P.G. gratefully acknowledges support from Science Foundation Ireland and the Royal Society in the form of a University Research Fellowship. Publisher Copyright: {\textcopyright} 2021 ESO. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",

year = "2021",

month = jan,

day = "1",

doi = "10.1051/0004-6361/202039135",

language = "English",

volume = "645",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol T OTO line list

AU - Serindag, Dilovan B.

AU - Nugroho, Stevanus K.

AU - Mollière, Paul

AU - De Mooij, Ernst J.W.

AU - Gibson, Neale P.

AU - Snellen, Ignas A.G.

N1 - Funding Information: cA knolw edgements. D.B.S., P.M., and I.A.G.S. acknowledge support from the European Research Council under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 694513. S.K.N. would like to acknowledge support from UK Science Technology and Facility Council grant ST/P000312/1. P.M. acknowledges support from the European Research Council under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 832428. N.P.G. gratefully acknowledges support from Science Foundation Ireland and the Royal Society in the form of a University Research Fellowship. Publisher Copyright: © 2021 ESO. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/1/1

Y1 - 2021/1/1

N2 - Context. Efficient absorption of stellar ultraviolet and visible radiation by TiO and VO is predicted to drive temperature inversions in the upper atmospheres of hot Jupiters. However, very few inversions or detections of TiO or VO have been reported, and results are often contradictory. Aims. Using the improved ExoMol TOTO line list, we searched for TiO emission in the dayside spectrum ofWASP-33b using the same data in which the molecule was previously detected with an older line list at 4.8σ. We intended to confirm the molecular detection and quantify the signal improvement offered by the ExoMol TOTO line list. Methods. Data from the High Dispersion Spectrograph on the Subaru Telescope was extracted and reduced in an identical manner to the previous study. Stellar and telluric contamination were then removed. High-resolution TiO emission models of WASP-33b were created that spanned a range of molecular abundances using the radiative transfer code petitRADTRANS, and were subsequently cross-correlated with the data. Results. We measure a 4.3σ TiO emission signature using the ExoMol TOTO models, corresponding to a WASP-33b orbital velocity semi-amplitude of Kp=252.9-5.3+5.0 km s-1 and a system velocity of vsys=-23.0-4.6+4.7 km s-1. Injection-recovery tests using models based on the new and earlier line lists indicate that if the new models provide a perfect match to the planet spectrum, the significance of the TiO detection should have increased by a factor of 2.Conclusions. Although the TiO signal we find is statistically significant, comparison with previous works makes our result too ambiguous to claim a clear-cut detection. Unexpectedly, the new ExoMol TOTO models provide a weaker signal than that found previously, which is offset in Kp-vsys space. This sheds some doubt on both detections, especially in light of a recently published TiO non-detection using a different dataset.

AB - Context. Efficient absorption of stellar ultraviolet and visible radiation by TiO and VO is predicted to drive temperature inversions in the upper atmospheres of hot Jupiters. However, very few inversions or detections of TiO or VO have been reported, and results are often contradictory. Aims. Using the improved ExoMol TOTO line list, we searched for TiO emission in the dayside spectrum ofWASP-33b using the same data in which the molecule was previously detected with an older line list at 4.8σ. We intended to confirm the molecular detection and quantify the signal improvement offered by the ExoMol TOTO line list. Methods. Data from the High Dispersion Spectrograph on the Subaru Telescope was extracted and reduced in an identical manner to the previous study. Stellar and telluric contamination were then removed. High-resolution TiO emission models of WASP-33b were created that spanned a range of molecular abundances using the radiative transfer code petitRADTRANS, and were subsequently cross-correlated with the data. Results. We measure a 4.3σ TiO emission signature using the ExoMol TOTO models, corresponding to a WASP-33b orbital velocity semi-amplitude of Kp=252.9-5.3+5.0 km s-1 and a system velocity of vsys=-23.0-4.6+4.7 km s-1. Injection-recovery tests using models based on the new and earlier line lists indicate that if the new models provide a perfect match to the planet spectrum, the significance of the TiO detection should have increased by a factor of 2.Conclusions. Although the TiO signal we find is statistically significant, comparison with previous works makes our result too ambiguous to claim a clear-cut detection. Unexpectedly, the new ExoMol TOTO models provide a weaker signal than that found previously, which is offset in Kp-vsys space. This sheds some doubt on both detections, especially in light of a recently published TiO non-detection using a different dataset.

KW - Planets and satellites: Atmospheres

KW - Planets and satellites: Composition

KW - Planets and satellites: Individual: WASP-33b

KW - Techniques: Spectroscopic

U2 - 10.1051/0004-6361/202039135

DO - 10.1051/0004-6361/202039135

M3 - Article

AN - SCOPUS:85099886824

SN - 0004-6361

VL - 645

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A90

ER -

Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol T OTO line list

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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