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users:mhooton:start [2018/10/02 15:59]
Matthew Hooton
users:mhooton:start [2018/10/10 14:55] (current)
Matthew Hooton
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 KELT-9b is a recently discovered exoplanet with a 1.49 d orbit around a B9.5/​A0-type star. The unparalleled levels of UV irradiation it receives from its host star put KELT-9b in its own unique class of ultra-hot Jupiters, with an equilibrium temperature > 4000 K. The high quantities of dissociated hydrogen and atomic metals present in the dayside atmosphere of KELT-9b bear more resemblance to a K-type star than a gas giant. We present a single observation of KELT-9b during its secondary eclipse, taken with the Wide Field Camera on the Isaac Newton Telescope (INT). This observation was taken in the U-band, a bandpass particularly sensitive to Rayleigh scattering. We do not detect a secondary eclipse signal, but our 3σ upper limit of 192 ppm on the depth allows us to constrain the dayside temperature of KELT-9b at pressures of ~30 mbar to 5035 K (3σ). Our models suggest that the scattering from the dayside of KELT-9b is negligible due to H<​sup>​-</​sup>​ opacity in the optical and NUV. This places KELT-9b squarely in the albedo regime populated by its cooler cousins, almost all of which reflect very small components of the light incident on their daysides. This work demonstrates the ability of ground-based 2m-class telescopes like the INT to perform secondary eclipse studies in the NUV, which to date have only been conducted from space-based facilities. KELT-9b is a recently discovered exoplanet with a 1.49 d orbit around a B9.5/​A0-type star. The unparalleled levels of UV irradiation it receives from its host star put KELT-9b in its own unique class of ultra-hot Jupiters, with an equilibrium temperature > 4000 K. The high quantities of dissociated hydrogen and atomic metals present in the dayside atmosphere of KELT-9b bear more resemblance to a K-type star than a gas giant. We present a single observation of KELT-9b during its secondary eclipse, taken with the Wide Field Camera on the Isaac Newton Telescope (INT). This observation was taken in the U-band, a bandpass particularly sensitive to Rayleigh scattering. We do not detect a secondary eclipse signal, but our 3σ upper limit of 192 ppm on the depth allows us to constrain the dayside temperature of KELT-9b at pressures of ~30 mbar to 5035 K (3σ). Our models suggest that the scattering from the dayside of KELT-9b is negligible due to H<​sup>​-</​sup>​ opacity in the optical and NUV. This places KELT-9b squarely in the albedo regime populated by its cooler cousins, almost all of which reflect very small components of the light incident on their daysides. This work demonstrates the ability of ground-based 2m-class telescopes like the INT to perform secondary eclipse studies in the NUV, which to date have only been conducted from space-based facilities.
  
-**[[https://​academic.oup.com/​mnras/​advance-article/doi/10.1093/mnras/sty2581/​5104393|NGTS-2b:​ An inflated hot-Jupiter transiting a bright F-dwarf - MNRAS]]** \\ +**[[https://​academic.oup.com/​mnras/​article-abstract/481/4/4960/​5104393|NGTS-2b:​ An inflated hot-Jupiter transiting a bright F-dwarf - MNRAS]]** \\ 
 We report the discovery of NGTS-2b, an inflated hot-Jupiter transiting a bright F5V star (2MASS J14202949-3112074;​ T<​sub>​eff</​sub>​= 6478+94−89 K), discovered as part of the Next Generation Transit Survey (NGTS). The planet is in a P=4.51 day orbit with mass 0.74+0.13−0.12 M<​sub>​J</​sub>,​ radius 1.595+0.047−0.045 R<​sub>​J</​sub>​ and density 0.226+0.040−0.038 We report the discovery of NGTS-2b, an inflated hot-Jupiter transiting a bright F5V star (2MASS J14202949-3112074;​ T<​sub>​eff</​sub>​= 6478+94−89 K), discovered as part of the Next Generation Transit Survey (NGTS). The planet is in a P=4.51 day orbit with mass 0.74+0.13−0.12 M<​sub>​J</​sub>,​ radius 1.595+0.047−0.045 R<​sub>​J</​sub>​ and density 0.226+0.040−0.038
 g cm<​sup>​−3</​sup>;​ therefore one of the lowest density exoplanets currently known. With a relatively deep 1.0% transit around a bright V=10.96 host star, NGTS-2b is a prime target for probing giant planet composition via atmospheric transmission spectroscopy. The rapid rotation (v sin i=15.2 ± 0.8 km s,<​sup>​−1</​sup>​) also makes this system an excellent candidate for Rossiter-McLaughlin follow-up observations,​ to measure the sky-projected stellar obliquity. NGTS-2b was confirmed without the need for follow-up photometry, due to the high precision of the NGTS photometry. g cm<​sup>​−3</​sup>;​ therefore one of the lowest density exoplanets currently known. With a relatively deep 1.0% transit around a bright V=10.96 host star, NGTS-2b is a prime target for probing giant planet composition via atmospheric transmission spectroscopy. The rapid rotation (v sin i=15.2 ± 0.8 km s,<​sup>​−1</​sup>​) also makes this system an excellent candidate for Rossiter-McLaughlin follow-up observations,​ to measure the sky-projected stellar obliquity. NGTS-2b was confirmed without the need for follow-up photometry, due to the high precision of the NGTS photometry.
users/mhooton/start.txt · Last modified: 2018/10/10 14:55 by Matthew Hooton

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