Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3

Beatty, Thomas G.; Madhusudhan, Nikku; Tsiaras, Angelos; Zhao, M.; Gilliland, Ronald L.; Knutson, Heather A.; Shporer, Avi; Wright, Jason T.

doi:10.3847/1538-3881/aa899b

Cited by 93 publications

(84 citation statements)

References 59 publications

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“…Alternatively, the cooler temperatures on the night-side could cause TiO and VO to condense out (primarily into Ti 3 O 5 and V 2 O 3 ), and due to the high-speed winds from day-to night-side expected in tidally-locked hot Jupiters, these condensed molecules are not efficiently redistributed to the hot day-side. Thus, Ti and V remain locked in condensed form (the cold-trapping effect: Hubeny et al 2003;Spiegel et al 2009;Parmentier et al 2013Parmentier et al , 2016Beatty et al 2017). However, the detection of Fe and Mg Gibson et al 2020;Bourrier et al 2020;Cabot et al 2020) in the atmosphere of WASP-121b suggests that coldtrapping does not play a large role, as we would expect Fe and Mg to be cold-trapped as well.…”

Section: Discussionmentioning

confidence: 99%

Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Merritt

Gibson

Nugroho

et al. 2020

A&A

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Thermal inversions have long been predicted to exist in the atmospheres of ultra-hot Jupiters. However, detection of two species thought to be responsible -TiO and VO -remain elusive. We present a search for TiO and VO in the atmosphere of the ultra-hot Jupiter WASP-121b (T eq 2400 K), an exoplanet already known to show water features in its dayside spectrum characteristic of a temperature inversion as well as tentative evidence for VO at low-resolution. We observed its transmission spectrum with UVES/VLT and used the cross-correlation method -a powerful tool for the unambiguous identification of the presence of atomic and molecular species -in an effort to detect whether TiO or VO were responsible for the observed temperature inversion. No evidence for the presence of TiO or VO was found at the terminator of WASP-121b. By injecting signals into our data at varying abundance levels, we set rough detection limits of [VO] −7.9 and [TiO] −9.3. However, these detection limits are largely degenerate with scattering properties and the position of the cloud deck. Our results may suggest that neither TiO or VO are the main drivers of the thermal inversion in WASP-121b, but until a more accurate line list is developed for VO, we cannot conclusively rule out its presence. Future work will search for finding other strong optically-absorbing species that may be responsible for the excess absorption in the redoptical.

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Section: Discussionmentioning

confidence: 99%

Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Merritt

Gibson

Nugroho

et al. 2020

A&A

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“…Furthermore, another ultra-hot Jupiter, Kepler-13Ab, which is hotter than WASP-18b, shows a strong H2O feature in absorption indicating the presence of H2O and lack of thermal inversion. This latter anomaly has been explained as due to the high mass and gravity of Kepler-13Ab which enhance cold-trap processes removing inversion-causing species (20).…”

Section: Temperature Structuresmentioning

confidence: 99%

Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects

Madhusudhan

2019

Annu. Rev. Astron. Astrophys.

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312

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Exoplanetary science is on the verge of an unprecedented revolution. The thousands of exoplanets discovered over the past decade have most recently been supplemented by discoveries of potentially habitable planets around nearby low-mass stars. Currently, the field is rapidly progressing towards detailed spectroscopic observations to characterise the atmospheres of these planets. While various surveys from space and ground are expected to detect numerous more exoplanets orbiting nearby stars, the imminent launch of JWST along with large groundbased facilities are expected to revolutionise exoplanetary spectroscopy. Such observations, combined with detailed theoretical models and inverse methods, provide valuable insights into a wide range of physical processes and chemical compositions in exoplanetary atmospheres. Depending on the planetary properties, the knowledge of atmospheric compositions can also place important constraints on planetary formation and migration mechanisms, geophysical processes and, ultimately, biosignatures. In the present review, we will discuss the modern and future landscape of this frontier area of exoplanetary atmospheres. We will start with a brief review of the area, emphasising the key insights gained from different observational methods and theoretical studies. This is followed by an in-depth discussion of the state-of-the-art, challenges, and future prospects in three forefront branches of the area. 2 N. Madhusudhan 6 N. Madhusudhan 28 N. Madhusudhan 42 N. Madhusudhan

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“…Mollière et al (2015) Suggested atomic Na and K are capable of leading to thermal inversions for a C/O ratio near 1. Beatty et al (2017a) Proposed that higher log(g) suppresses inversions due to cold-trap processes. Lothringer et al (2018) Proposed Fe, Mg, SiO and metal hydrides as candidates for inversions on planets with Teq>2500 K.…”

Section: Studymentioning

confidence: 99%

New avenues for thermal inversions in atmospheres of hot Jupiters

Gandhi

Madhusudhan

2019

Monthly Notices of the Royal Astronomical Society

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Thermal emission spectra of hot Jupiters have led to key constraints on thermal inversions (or 'stratospheres') in their atmospheres with important implications for their atmospheric processes. Canonically, thermal inversions in hot Jupiters have been suggested to be caused by species such as TiO and VO which have strong visible opacity to absorb incident starlight. We explore two new avenues for thermal inversions in hot Jupiters, exploring both the visible and infrared opacities in their atmospheres. Firstly, by exploring a range of metal-rich species we find that four species (AlO, CaO, NaH and MgH) provide visible opacities comparable to TiO/VO and can cause strong inversions with reasonable abundances. Secondly, we show that a low infrared opacity caused by a low H 2 O abundance, e.g. through a C/O∼ 1, can also lead to strong thermal inversions even with low abundances of the visible absorbers mentioned above. We find that increasing the C/O ratio towards unity requires almost 2 orders of magnitude lower abundances for the visible absorbers in order for an inversion to form. Finally, we explore the thermal inversion in WASP-121b and find that it can be explained by all the visible absorbers listed above for different C/O ratios. Our study demonstrates the importance of both the refractory and volatile species in governing the physicochemical processes in hot Jupiter atmospheres. Spectroscopic observations in the visible have the potential to detect the newly proposed refractory species that can cause thermal inversions in addition to TiO and VO.

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Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3

Cited by 93 publications

References 59 publications

Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects

New avenues for thermal inversions in atmospheres of hot Jupiters

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