Detection of Ionized Calcium in the Atmosphere of the Ultra-hot Jupiter KELT-9b

Turner, Jake D.; Mooij, Ernst de; Jayawardhana, Ray; Young, Mitchell E.; Fossati, L.; Koskinen, Tommi; Lothringer, Joshua D.; Karjalainen, R.; Karjalainen, Marie

doi:10.3847/2041-8213/ab60a9

Cited by 81 publications

(114 citation statements)

References 60 publications

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“…We note that the planetary disk ignores the wavelength-dependent effect of the planetary radius caused by its atmosphere. As mentioned in Turner et al (2020), the R-M effect is underestimated at the wavelength where the absorption from the planetary atmosphere is strong. To ensure that the model only includes the R-M and CLV effects, for each observation we divided the model by the out-of-transit spectrum after continuum normalisation, and this was subsequently divided out of the data.…”

Section: Data Preparationmentioning

confidence: 84%

“…To avoid this, we chose to use the same number of SYSREM iterations for all orders that maximises the S/N of the detected signal (e.g. De Kok et al 2013;Birkby et al 2017;Turner et al 2020). This method would not result in the true optimised number of SYSREM iterations and might introduce additional noise from the order that has not been 'completely cleaned' by SYSREM as has been pointed out by Alonso-Floriano et al 2019), but it would not affect the result significantly if the S/N of the detection is strong, to begin with.…”

Section: Removal Of Stellar and Telluric Linesmentioning

confidence: 99%

“…One could stack the in-transit spectra at the planetary rest frame and search for absorption features at specific wavelengths (e.g. Redfield et al 2008;Snellen et al 2008;Wood et al 2011;Zhou & Bayliss 2012;Wyttenbach et al 2015Wyttenbach et al , 2017Yan & Henning 2018;Casasayas-Barris et al 2018;Cauley et al 2019;Casasayas-Barris et al 2019;Yan et al 2019;Turner et al 2020). This method works well mostly for strong absorption lines (e.g.…”

Section: S E a R C H I N G F O R At M O S P H E R I C S I G Na L Smentioning

confidence: 99%

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Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Nugroho

Gibson

Mooij

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We analyse the transmission spectra of KELT-20b/MASCARA-2b to search for possible thermal inversion agents. The data consist of three transits obtained using HARPSN and one using CARMENES. We removed stellar and telluric lines before cross-correlating the residuals with spectroscopic templates produced using a 1D plane-parallel model, assuming an isothermal atmosphere and chemical equilibrium at solar metallicity. Using a likelihood-mapping method, we detect Fe i at > 13σ, Ca ii H$\&$K at > 6σ and confirm the previous detections of Fe ii, Ca ii IR Triplet, and Na i D. The detected signal of Fe i is shifted by −3.4 ± 0.4 km s−1 from the planetary rest frame, which indicates a strong day–night wind. Our likelihood-mapping technique also reveals that the absorption features of the detected species extend to different altitudes in the planet’s atmosphere. Assuming that the line lists are accurate, we do not detect other potential thermal inversion agents (NaH, MgH, AlO, SH, CaO, VO, FeH, and TiO) suggesting that non-chemical equilibrium mechanisms (e.g. a cold-trap) might have removed Ti- and V-bearing species from the upper atmosphere. Our results, therefore, show that KELT-20b/MASCARA-2b cannot possess an inversion layer caused by a TiO/VO-related mechanism. The presence of an inversion layer would therefore likely be caused by metal atoms such as Fe i and Fe ii. Finally, we report a double-peak structure in the Fe i signal in all of our data sets that could be a signature of atmospheric dynamics. However, further investigation is needed to robustly determine the origin of the signal.

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Section: Data Preparationmentioning

confidence: 84%

Section: Removal Of Stellar and Telluric Linesmentioning

confidence: 99%

Section: S E a R C H I N G F O R At M O S P H E R I C S I G Na L Smentioning

confidence: 99%

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Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Nugroho

Gibson

Mooij

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The detections of Fe I, Fe II, Ti II (but not of Ti I; Hoeijmakers et al 2018) are confirming the predicted presence of neutral and ionized species in ultra-hot Jupiters. In Cauley et al (2019); Hoeijmakers et al (2019); Yan et al (2019); Turner et al (2020), more neutral and ionized atomic species are reported, such as Na I, Ca I, Ca II, Mg I, Cr II, Sc II, and Y II. In KELT-9 b, ionized species are more abundant than neutral species, which is A. Wyttenbach et al: Hydrogen Balmer series in KELT-9 b thermosphere Table 2.…”

Section: Parametermentioning

confidence: 99%

Mass-loss rate and local thermodynamic state of the KELT-9 b thermosphere from the hydrogen Balmer series

Wyttenbach

Mollière

Ehrenreich

et al. 2020

A&A

153

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KELT-9 b, the hottest known exoplanet, with Teq ~ 4400 K, is the archetype of a new planet class known as ultra-hot Jupiters. These exoplanets are presumed to have an atmosphere dominated by neutral and ionized atomic species. In particular, Hα and Hβ Balmer lines have been detected in the KELT-9 b upper atmosphere, suggesting that hydrogen is filling the planetary Roche lobe and escaping from the planet. In this work, we detected δ Scuti-type stellar pulsation (with a period Ppuls = 7.54 ± 0.12 h) and studied the Rossiter-McLaughlin effect (finding a spin-orbit angle λ = −85.01° ± 0.23°) prior to focussing on the Balmer lines (Hα to Hζ) in the optical transmission spectrum of KELT-9 b. Our HARPS-N data show significant absorption for Hα to Hδ. The precise line shapes of the Hα, Hβ, and Hγ absorptions allow us to put constraints on the thermospheric temperature. Moreover, the mass loss rate, and the excited hydrogen population of KELT-9 b are also constrained, thanks to a retrieval analysis performed with a new atmospheric model. We retrieved a thermospheric temperature of T = 13 200−720+800 K and a mass loss rate of Ṁ = 1012.8±0.3 g s−1 when the atmosphere was assumed to be in hydrodynamical expansion and in local thermodynamic equilibrium (LTE). Since the thermospheres of hot Jupiters are not expected to be in LTE, we explored atmospheric structures with non-Boltzmann equilibrium for the population of the excited hydrogen. We do not find strong statistical evidence in favor of a departure from LTE. However, our non-LTE scenario suggests that a departure from the Boltzmann equilibrium may not be sufficient to explain the retrieved low number densities of the excited hydrogen. In non-LTE, Saha equilibrium departure via photo-ionization, is also likely to be necessary to explain the data.

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“…In addition, as molecules responsible for radiative cooling (e.g., H 2 O) are destroyed by the high dayside temperature (Kitzmann et al 2018;Parmentier et al 2018), refractory elements such as Fe and Mg continue to absorb incident starlight at UV and optical wavelengths and heat the atmosphere at low pressures, inducing a significant dayside temperature inversion (Kitzmann et al 2018;Lothringer et al 2018). Previous observations of KELT-9b have revealed many characteristics that are hallmarks of UHJs, including an extended, escaping atmosphere of dissociated hydrogen (Yan & Henning 2018) and spectral features from ionized Fe, Ti, Mg, Ca, Na, Cr, Sc, and Y in optical transmission spectroscopy (Hoeijmakers et al 2018(Hoeijmakers et al , 2019Yan & Henning 2018;Cauley et al 2019;Turner et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Exploring the Atmospheric Dynamics of the Extreme Ultrahot Jupiter KELT-9b Using TESS Photometry

Wong¹,

Shporer²,

Kitzmann³

et al. 2020

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We carry out a phase-curve analysis of the KELT-9 system using photometric observations from NASA's Transiting Exoplanet Survey Satellite (TESS). The measured secondary eclipse depth and peak-to-peak atmospheric brightness modulation are-+ 650 15 14 and 566±16 ppm, respectively. The planet's brightness variation reaches maximum 31±5minutes before the midpoint of the secondary eclipse, indicating a 5°.2±0°.9 eastward shift in the dayside hot spot from the substellar point. We also detect stellar pulsations on KELT-9 with a period of 7.58695±0.00091hr. The dayside emission of KELT-9b in the TESSbandpass is consistent with a blackbody brightness temperature of 4600±100 K. The corresponding nightside brightness temperature is 3040±100 K, comparable to the dayside temperatures of the hottest known exoplanets. In addition, we detect a significant phase-curve signal at the first harmonic of the orbital frequency and a marginal signal at the second harmonic. While the amplitude of the first harmonic component is consistent with the predicted ellipsoidal distortion modulation assuming equilibrium tides, the phase of this photometric variation is shifted relative to the expectation. Placing KELT-9b in the context of other exoplanets with phase-curve observations, we find that the elevated nightside temperature and relatively low day-night temperature contrast agree with the predictions of atmospheric models that include H 2 dissociation and recombination. The nightside temperature of KELT-9b implies an atmospheric composition containing about 50% molecular and 50% atomic hydrogen at 0.1bar, a nightside emission spectrum that deviates significantly from a blackbody, and a 0.5-2.0 μm transmission spectrum that is featureless at low resolution.

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Detection of Ionized Calcium in the Atmosphere of the Ultra-hot Jupiter KELT-9b

Cited by 81 publications

References 60 publications

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Mass-loss rate and local thermodynamic state of the KELT-9 b thermosphere from the hydrogen Balmer series

Exploring the Atmospheric Dynamics of the Extreme Ultrahot Jupiter KELT-9b Using TESS Photometry

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