TY - JOUR
T1 - Detection of ionized calcium in the atmosphere of the ultra-hot Jupiter Kelt-9b
AU - Turner, Jake D.
AU - de Mooij, Ernst J.W.
AU - Jayawardhana, Ray
AU - Young, Mitchell E.
AU - Fossati, Luca
AU - Koskinen, Tommi
AU - Lothringer, Joshua D.
AU - Karjalainen, Raine
AU - Karjalainen, Marie
N1 - Funding Information:
CARMENES was funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Científicas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium, with additional contributions by the Spanish Ministry of Science, the German Science Foundation (DFG), the Klaus Tschira Stiftung, the states of Baden-Württemberg and Niedersachsen, and by the Junta de Andalucia.
Funding Information:
Services, and the the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This research also made use of the NIST Atomic Spectra Database funded [in part] by NIST’s Standard Reference Data Program (SRDP) and by NIST’s Systems Integration for Manufacturing Applications (SIMA) Program.
PY - 2020/1/1
Y1 - 2020/1/1
N2 - With a dayside temperature in excess of 4500 K, comparable to a mid-K-type star, KELT-9b is the hottest planet known. Its extreme temperature makes KELT-9b a particularly interesting test bed for investigating the nature and diversity of gas giant planets. We observed the transit of KELT-9b at high spectral resolution (R ∼ 94,600) with the CARMENES instrument on the Calar Alto 3.5 m telescope. Using these data, we detect for the first time ionized calcium (Ca II triplet) absorption in the atmosphere of KELT-9b; this is the second time that Ca II has been observed in a hot Jupiter. Our observations also reveal prominent Hα absorption, confirming the presence of an extended hydrogen envelope around KELT-9b. We compare our detections with an atmospheric model and find that all four lines form between atmospheric temperatures of 6100 and 8000 K and that the Ca II lines form at pressures between 50 and 100 nbar while the Hα line forms at a lower pressure (∼10 nbar), higher up in the atmosphere. The altitude that the core of Hα line forms is found to be ∼1.4 Rp, well within the planetary Roche lobe (∼1.9 Rp). Therefore, rather than probing the escaping upper atmosphere directly, the Hα line and the other observed Balmer and metal lines serve as atmospheric thermometers enabling us to probe the planet’s temperature profile, thus the energy budget.
AB - With a dayside temperature in excess of 4500 K, comparable to a mid-K-type star, KELT-9b is the hottest planet known. Its extreme temperature makes KELT-9b a particularly interesting test bed for investigating the nature and diversity of gas giant planets. We observed the transit of KELT-9b at high spectral resolution (R ∼ 94,600) with the CARMENES instrument on the Calar Alto 3.5 m telescope. Using these data, we detect for the first time ionized calcium (Ca II triplet) absorption in the atmosphere of KELT-9b; this is the second time that Ca II has been observed in a hot Jupiter. Our observations also reveal prominent Hα absorption, confirming the presence of an extended hydrogen envelope around KELT-9b. We compare our detections with an atmospheric model and find that all four lines form between atmospheric temperatures of 6100 and 8000 K and that the Ca II lines form at pressures between 50 and 100 nbar while the Hα line forms at a lower pressure (∼10 nbar), higher up in the atmosphere. The altitude that the core of Hα line forms is found to be ∼1.4 Rp, well within the planetary Roche lobe (∼1.9 Rp). Therefore, rather than probing the escaping upper atmosphere directly, the Hα line and the other observed Balmer and metal lines serve as atmospheric thermometers enabling us to probe the planet’s temperature profile, thus the energy budget.
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U2 - 10.3847/2041-8213/ab60a9
DO - 10.3847/2041-8213/ab60a9
M3 - Article
AN - SCOPUS:85079782904
VL - 888
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
ER -