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Today my paper "Detection of ionized calcium in the atmosphere of the ultra-hot Jupiter KELT-9b" came out on ArXiv: https://arxiv.org/abs/1910.06882 .
@Cornell @CSInst @CornellAstro @CARMENES_exopl @UAresearch @DrRayJay #Exoplanets #HotJupiter #Astronomy
Thread 1/pic.twitter.com/tqVpBm4Q6T
Main Results: - We detect for the first time ionized calcium (CaII triplet) absorption in the atmosphere of KELT-9b. - Our observations also reveal prominent H-alpha absorption, confirming the presence of an extended hydrogen envelope around KELT-9b. 2/pic.twitter.com/XSfA2oJJCr
Main Results: - We derived the atmospheric altitude, pressure, temperature, and number density where the hydrogen (H-alpha line) and CaII triplet lines are formed. This is rarely done in exoplanet science and opens up a new way to study atmospheric structures. 3/pic.twitter.com/hwiP6gUu5i
Main Result: - The altitude that the core of H-alpha line forms is found to be ∼1.33 Rplanet, well within the planetary Roche lobe (∼1.91Rp). - We find for KELT-9b the H-alpha line does not directly probe the escaping upper atmosphere. 4/pic.twitter.com/6samU7viK6
Meet KELT-9b: A Gas Giant Planet So Hot, It Rivals Our Sun https://curiosity.com/topics/meet-kelt-9b-a-gas-giant-planet-so-hot-it-rivals-our-sun-curiosity/ …
KELT-9b is a ultra-hot Jupiter with a period of 1.5 days, an orbital distance of 0.03 AU (10 times closer than the orbit of Mercury). and it orbits a A0 star with an effective temperature of 10,000 K. The system is 620 light years from Earth. 2/pic.twitter.com/ZPBruKYFYM
As a result of its close-in orbit, KELT-9b is the hottest gas giant exoplanet known, with a dayside temperature of ~4,500 K (4200 degrees Celsius), which makes it hotter than M-type stars, and many K-type stars. 3/https://www.skyandtelescope.com/astronomy-news/kelt-9b-hottest-hot-jupiter/ …
Since this target is very interesting and extreme, many groups have observed it. Yan & Thomas 2018 found that the planet had an extended hydrogen envelope. https://www.nature.com/articles/s41550-018-0534-9 … 4/
Additional observations by Hoeijmakers et al. 2018 found iron and titanium in the atmosphere of KELT-9b https://scitechdaily.com/astronomers-discover-iron-and-titanium-in-atmosphere-exoplanet-kelt-9b/ … 5/
In total, 14 atomic species have been reported previously in KELT-9b’s atmosphere using data from three different groups. This is the most for any exoplanet so far. 6/pic.twitter.com/FhtQn1Ujg4
Our team observed this target in June 2018 (months before I started my postdoc at @Cornell) to learn more about the system and search for additional atomic species in its atmosphere. We observed with the @CARMENES_exopl instrument on the 3.5-m Calar Alto telescope. 7/pic.twitter.com/fxHS6MFkEh
We observed KELT9-b during transit at high-resolution (R~90,000). High-resolution is important because we can separate the contribution of the planet orbiting its star from the star itself. 8/pic.twitter.com/FYJGL8QUno
Figure 1 shows our reduction steps. Panel c shows the reducted data. The biggest problem we had to address was how to get rid of the stellar and Earth's atmopshere. We used a variety of techniques (see Appendix A) to accomplish this task and all resulted in the same results. 9/pic.twitter.com/c0sVXgEG46
- We unambiguously detect atmospheric absorption due to H-alpha and the CaII infrared triplet Doppler-shifted with the planet’s orbital motion (left panels below). - Our observations confirm the presence of an extended hydrogen envelope around KELT-9b. 10/pic.twitter.com/qrPh5FQ8kM
We compare our detections with an atmospheric model to derive the physical conditions where the lines formed (altitude, temperature, density, and pressure). The models are shown in the right panels. 11/pic.twitter.com/IfFBKEfx1P
We derive the effective planetary radius at line center, atmospheric pressure, temperature, and number density for each Ca II and H-alpha. - CaII is formed at a radius of 1.2 Rplanet where the H-alpha is formed at a radius of 1.33 Rplanet. 12/pic.twitter.com/zWkl5bYDTc
This figure shows where the Ca II (1.2) and H-alpha (1.33) lines are formed relative to the Roche Lobe of the planet (1.9 Rp) 13/pic.twitter.com/JQFwypiRIq
Atmospheric profiles for the H-alpha and the CaII infrared triplet lines derived from the atmospheric model. - H-alpha is formed at a pressure of ∼10 nbar. - The Ca II lines are formed between 30 and 120 nbar - Form between a temperature of 6100 K and 8000 K 14/pic.twitter.com/Y6bTv7CEjI
Our modeling shows that the atmosphere at the levels probed by the Hα line is not in a hydrodynamic regime and that on KELT-9b this line does not directly probe the escaping upper atmosphere. 15/pic.twitter.com/GaWEN6HMPw
KELT-9b should host an escaping upper atmosphere but ultraviolet observations from @NASAHubble will be needed to directly probe that escape.
16/pic.twitter.com/xbXpuRUmio
In this paper, we show the promise of using individual absorption lines to study the structure of exoplanetary atmospheres. - We are hoping to expand this type of analysis to many more systems. 17/End
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