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Post Info TOPIC: WASP-33
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WASP-33b
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Title: A temperature inversion in WASP-33b? Large Binocular Telescope occultation data confirm significant thermal flux at short wavelengths
Author: C. von Essen, M. Mallonn, S. Albrecht, V. Antoci, A. M. S. Smith, S. Dreizler, K. G. Strassmeier

We observed a secondary eclipse of WASP-33b quasi-simultaneously in the optical (~0.55 µm) and the near-infrared (~1.05 µm) using the 2x8.4 m Large Binocular Telescope. WASP-33 is a {\delta} Scuti star pulsating with periods comparable to the eclipse duration, making the determination of the eclipse depth challenging. We use previously determined oscillation frequencies to model and remove the pulsation signal from the light curves, isolating the secondary eclipse. The determined eclipse depth is dF = 1.03 ± 0.34 parts per thousand, corresponding to a brightness temperature of Tb = 3398 ± 302 K. Combining previously published data with our new measurement we find the equilibrium temperature of WASP-33b to be Tb = 3358 ± 165 K. We compare all existing eclipse data to a blackbody spectrum, to a carbon-rich non-inverted model and to a solar composition model with an inverted temperature structure. We find that current available data on WASP-33b's atmosphere can be best represented by a simple blackbody emission, without the need for more sophisticated atmospheric models with temperature inversions. Although our data cannot rule out models with or without a temperature inversion, they do confirm a high brightness temperature for the planet at short wavelengths. WASP-33b is one of the hottest exoplanets known till date, and its equilibrium temperature is consistent with rapid reradiation of the absorbed stellar light and a low albedo.

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Hubble Telescope Detects 'Sunscreen' Layer on Distant Planet

Researchers using NASA's Hubble Space Telescope have detected a stratosphere and temperature inversion in the atmosphere of a planet several times the mass of Jupiter, called WASP-33b.
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Blobrana


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HD 15082 b
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Title: Comprehensive time series analysis of the transiting extrasolar planet WASP-33b
Authors: G. Kovács, T. Kovács, J.D. Hartman, G. A. Bakos, A. Bieryla, D. Latham, R.W. Noyes, Zs. Regály, G.A. Esquerdo

HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbour a transiting extrasolar planet (WASP-33b). The lack of high precision radial velocity (RV) data tresses the need for precise light curve analysis and gathering further RV data. By using available photometric and RV data, we perform a blend analysis, compute more accurate system parameters, confine the planetary mass and attempt to cast light on the observed transit anomalies. We combine the original HATNet observations and various follow-up data to jointly analyse the signal content and extract the transit component and use our RV data to aid the global parameter determination. The blend analysis of the combination of multicolour light curves yields the first independent confirmation of the planetary nature of WASP-33b. We clearly identify three frequency components in the 15-21 d^{-1} regime with amplitudes 7-5 mmag. These frequencies correspond to the delta Scuti-type pulsation of the host star. None of these pulsation frequencies or their low-order linear combinations are in close resonance with the orbital frequency. We show that these pulsation components explain some but not all of the observed transit anomalies. The grand-averaged transit light curve shows that there is a ~ 2 mmag brightening shortly after the planet passes the mid-transit phase. We suggest that the most likely explanation of this feature is the presence of a well-populated spot belt which is highly inclined to the orbital plane. This geometry is consistent with the inference from the spectroscopic anomalies. Finally, we constrain the planetary mass to M_p=3.18±0.82 Jupiter masses by using our RV data collected by the TRES spectrograph.

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Blobrana


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RE: WASP-33
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A team of astronomers in Britain believe they have discovered the hottest planet ever found.
While Venus, right here in our own solar system, was once the hottest known planet, astronomers in the past 20 years have expanded their search to other solar systems.
As a result, planets have been identified that far exceed the 460 degrees Celsius temperature of Venus -- some with scorching temperatures approaching 1,000 C.
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Blobrana


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RE: WASP-33b
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Astronomers have found the hottest planet yet, a gas giant with a temperature of nearly 3200 °C, which is hotter than some stars.
A collaboration called the Super Wide Angle Search for Planets (SuperWASP) announced hints of the planet's existence in 2006. The group had observed periodic dimmings of the parent star possibly caused by a planet about 1.4 times the size of Jupiter passing in front of the star once per orbit.
Follow-up measurements confirmed the planet's presence in 2010, showing distortions of the star's light spectrum that could only be due to a planet's influence. The measurements showed the planet's mass is less than 4.5 times that of Jupiter.
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Blobrana


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RE: WASP-33
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New Pulsating Star That Hosts A Giant Planet

Recently published in an article of the Astronomy & Astrophysics journal, a group of researchers from the Institute of Space Sciences (IEEC-CSIC) at Universitat Autňnoma de Barcelona has discovered, for the first time, a delta Scuti pulsating star that hosts a hot giant transiting planet.
The study was carried out by the PhD student, Enrique Herrero, the researcher Dr. Juan Carlos Morales, the exoplanet expert, Dr. Ignasi Ribas, and the amateur astronomer, Mr. Ramón Naves.
WASP-33 (also known as HD15082) is hotter, more massive than the Sun (1.5 Msun) and is located at a distance of 378 light years away, in the constellation of Andromeda.
It has the peculiarity of being a star that pulsates radially, like a balloon that inflates and deflates continuously, and non-radially, like the tides in Earth's oceans caused by the presence of the moon, which deforms the bodies of water between the poles and the equator.
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Title: WASP-33: The first delta Scuti exoplanet host star
Authors: Herrero E., Morales J.C., Ribas I., Naves R.

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Title: WASP-33: The first delta Scuti exoplanet host star
Authors: E. Herrero (IEEC-CSIC), J.C. Morales (IEEC-CSIC), I. Ribas (IEEC-CSIC), R. Naves (Montcabrer Obs.)
(Version v2)

We report the discovery of photometric oscillations in the host star of the exoplanet WASP-33 b (HD 15082). The data were obtained in the R band in both transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory. Proper fitting and subsequent removal of the transit signal reveals stellar photometric variations with a semi-amplitude of about 1 mmag. The detailed analysis of the periodogram yields a structure of significant signals around a frequency of 21 cyc per day, which is typical of delta Scuti-type variable stars. An accurate study of the power spectrum reveals a possible commensurability with the planet orbital motion with a factor of 26, but this remains to be confirmed with additional time-series data that will permit the identification of the significant frequencies. These findings make WASP-33 the first transiting exoplanet host star with delta Sct variability and a very interesting candidate to search for star-planet interactions.

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