Astronomy:WASP-33b

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Short description: Hot Jupiter orbiting HD 15082
WASP-33b
Discovery[1]
Discovered byWASP
Discovery date2010
Transit
Orbital characteristics
0.02555 ± 0.00017 AU (3,822,200 ± 25,432 km) [1]
Orbital period1.21987089 ± 0.00000015 days (105,396.845 ± 0.013 s; 29.2769014 ± 3.6×10−6 h) [2]
Inclination87.67±1.81°[1]
Semi-amplitude0.59 km/s (1,300 mph) [1]
StarHD 15082
Physical characteristics
Mean radius1.497±0.095 |♃|J}}}}}}[1]
Mass2.81±0.53 |♃|J}}}}}}[3]
Albedo0.369±0.050[3]
Physics2,710 ± 50 K (2,440 ± 50.0 °C; 4,420 ± 90.0 °F) [1]


WASP-33b is an extrasolar planet orbiting the star HD 15082. It was the first planet discovered to orbit a Delta Scuti variable star. With a semimajor axis of 0.026 astronomical unit|AU (3.9 million km; 2.4 million mi) and a mass likely greater than Jupiter's,[1] it belongs to the hot Jupiter class of planets.

Discovery

In 2010, the SuperWASP project announced the discovery of an extrasolar planet orbiting the star HD 15082. The discovery was made by detecting the transit of the planet as it passes in front of its star, an event that occurs every 1.22 days.

Orbit

A study in 2012, utilizing the Rossiter–McLaughlin effect, determined the planetary orbit is strongly misaligned with the equatorial plane of the star, misalignment equal to −107.7±1.6°, making the orbit of WASP-33b retrograde.[4] The periastron node is precessing with a period of 709+33−34 years.[5]

Physical characteristics

Limits from radial velocity measurements imply it has less than 4.1 times the mass of Jupiter.[1] The exoplanet orbits so close to its star that its surface temperature is about 3,200 °C (5,790 °F).[6] The transit was later recovered in Hipparcos data.[7]

Atmosphere

In June 2015, NASA reported the exoplanet has a stratosphere, and the atmosphere contains titanium monoxide, which creates the stratosphere. Titanium oxide is one of only a few compounds that is a strong absorber of visible and ultraviolet radiation, which heats the atmosphere, and is able to exist in a gas state in a hot atmosphere.[8][9] The detection of temperature inversion (stratosphere), water and titanium oxide was disproved with the higher quality data obtained by 2020. Only upper limit of titanium oxide volume mixing rate equal to 1 ppb can be obtained.[10] Later research reconfirmed the existence of titanium oxide in the atmosphere of WASP-33b, although in concentrations not detectable by HARPS-N. The neutral iron[11] and silicon[12] were also detected.

Atmosphere of WASP-33b was detected by monitoring light as the planet passed behind its star (top)—higher temperatures result in the low stratosphere due to molecules absorbing radiation from the star (right)—lower temperatures at higher altitudes would result if there were no stratosphere (left)[8]

In 2020, with the detection of secondary eclipses (when the planet is blocked by its star), the mass of the planet along with temperature profile across its surface was measured. WASP-33b has strong winds in its atmosphere, similar to Venus, shifting the hottest spot 28.7±7.1 degrees to the west. The averaged wind speed is 8.5+2.1−1.9 km/s in the thermosphere.[13] The illuminated side brightness temperature is 3,014 ± 60 K (2,740.8 ± 60.0 °C; 4,965.5 ± 108.0 °F), while the nightside brightness temperature is 1,605 ± 45 K (1,331.8 ± 45.0 °C; 2,429.3 ± 81.0 °F).[3]

The atmospheric escape driven by hydrogen Balmer line absorption is relatively modest, totaling about one to ten Earth masses per billion years.[14]

The water in dayside atmosphere of WASP-33b is mostly dissociated to hydroxyl radicals due to high temperature, as planetary emission spectra indicated.[15]

Non-Keplerian features of motion for WASP-33b

In view of the high rotational speed of its parent star, the orbital motion of WASP-33b may be affected in a measurable way by the huge oblateness of the star and effects of general relativity.

First, the distorted shape of the star makes its gravitational field deviate from the usual Newtonian inverse-square law. The same is true for the Sun, and part of the precession of the orbit of Mercury is due to this effect. However, it is estimated to be [math]\displaystyle{ 9 \times 10^9 }[/math] greater for WASP-33b.[16]

Other effects will also be greater for WASP-33b. In particular, precession due to general relativistic frame-dragging should be [math]\displaystyle{ 3 \times 10^5 }[/math] greater for WASP-33b than for Mercury, where it is so far too small to have been observed. It has been argued that the oblateness of HD 15082 could be measured at a percent accuracy from a 10-year analysis of the time variations of the planet's transits.[16] Effects due to the planet's oblateness are smaller by at least one order of magnitude, and they depend on the unknown angle between the planet's equator and the orbital plane, perhaps making them undetectable. The effects of frame-dragging are slightly too small to be measured by such an experiment.

Nodal precession of WASP-33b, caused by oblateness of the parent star, was measured by 2021. The gravitational quadrupole moment of the HD 15082 was found to be equal to 6.73±0.22×10−5. The non-Keplerian precession is expected to be 500 times smaller, yet to be detected.[17]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Collier Cameron, A. et al. (2010). "Line-profile tomography of exoplanet transits - II. A gas-giant planet transiting a rapidly rotating A5 star". Monthly Notices of the Royal Astronomical Society 407 (1): 507. doi:10.1111/j.1365-2966.2010.16922.x. Bibcode: 2010MNRAS.407..507C. 
  2. ↑ Zhang, Michael et al. (2017). "Phase curves of WASP-33b and HD 149026b and a New Correlation Between Phase Curve Offset and Irradiation Temperature". The Astronomical Journal 155 (2): 83. doi:10.3847/1538-3881/aaa458. Bibcode: 2018AJ....155...83Z. 
  3. ↑ 3.0 3.1 3.2 von Essen, C.; Mallonn, M.; Borre, C. C.; Antoci, V.; Stassun, K. G.; Khalafinejad, S.; Tautvaivsiene, G. (2020). "TESS unveils the phase curve of WASP-33b. Characterization of the planetary atmosphere and the pulsations from the star". Astronomy & Astrophysics A34: 639. doi:10.1051/0004-6361/202037905. Bibcode: 2020A&A...639A..34V. 
  4. ↑ Albrecht, Simon; Winn, Joshua N. et al. (August 30, 2012). "Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments". The Astrophysical Journal 757 (1): 18. doi:10.1088/0004-637X/757/1/18. Bibcode: 2012ApJ...757...18A. https://iopscience.iop.org/article/10.1088/0004-637X/757/1/18. Retrieved March 28, 2022. 
  5. ↑ Watanabe, Noriharu; Narita, Norio; Palle, Enric (March 3, 2022). "Nodal Precession of WASP-33b for Eleven Years by Doppler Tomographic and Transit Photometric Observations". Monthly Notices of the Royal Astronomical Society. doi:10.1093/mnras/stac620. 
  6. ↑ "Hottest planet is hotter than some stars". https://www.newscientist.com/article/dn19991-hottest-planet-is-hotter-than-some-stars.html. 
  7. ↑ McDonald, I.; Kerins, E. (2018). "Pre-discovery transits of the exoplanets WASP-18b and WASP-33b from Hipparcos". Monthly Notices of the Royal Astronomical Society 477 (1): L21. doi:10.1093/mnrasl/sly045. Bibcode: 2018MNRAS.477L..21M. 
  8. ↑ 8.0 8.1 Northon, Karen, ed (June 11, 2015). "NASA's Hubble Telescope Detects 'Sunscreen' Layer on Distant Planet". https://www.nasa.gov/press-release/nasa-s-hubble-telescope-detects-sunscreen-layer-on-distant-planet. 
  9. ↑ Haynes, Korey; Mandell, Avi M. et al. (June 12, 2015). "Spectroscopic Evidence for a Temperature Inversion in the Dayside Atmosphere of the Hot Jupiter WASP-33b". The Astrophysical Journal 806 (2): 146. doi:10.1088/0004-637X/806/2/146. Bibcode: 2015ApJ...806..146H. https://iopscience.iop.org/article/10.1088/0004-637X/806/2/146. Retrieved March 28, 2022. 
  10. ↑ Herman, Miranda K.; Mooij, Ernst J. W. de et al. (July 31, 2020). "Search for TiO and Optical Nightside Emission from the Exoplanet WASP-33b". The Astronomical Journal 160 (2): 93. doi:10.3847/1538-3881/ab9e77. Bibcode: 2020AJ....160...93H. 
  11. ↑ Cont, D.; Yan, F.; Reiners, A.; Casasayas-Barris, N.; Mollière, P.; Pallé, E.; Henning, Th.; Nortmann, L. et al. (2021), "Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b", Astronomy & Astrophysics 651: A33, doi:10.1051/0004-6361/202140732, Bibcode: 2021A&A...651A..33C 
  12. ↑ Cont, D.; Yan, F.; Reiners, A.; Nortmann, L.; Molaverdikhani, K.; Pallé, E.; Stangret, M.; Henning, Th. et al. (2022), "Silicon in the dayside atmospheres of two ultra-hot Jupiters", Astronomy & Astrophysics 657: L2, doi:10.1051/0004-6361/202142776, Bibcode: 2022A&A...657L...2C 
  13. ↑ Wilson Cauley, P.; Wang, Ji et al. (2021), "Time-resolved rotational velocities in the upper atmosphere of WASP-33 b", The Astronomical Journal 161 (3): 152, doi:10.3847/1538-3881/abde43, Bibcode: 2021AJ....161..152C 
  14. ↑ Yan, F.; Wyttenbach, A. et al. (January 2021). "Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b". Astronomy & Astrophysics 645: A22. doi:10.1051/0004-6361/202039302. ISSN 0004-6361. Bibcode: 2021A&A...645A..22Y. https://www.aanda.org/10.1051/0004-6361/202039302. Retrieved March 28, 2022. 
  15. ↑ Nugroho, Stevanus K.; Kawahara, Hajime; Gibson, Neale P.; De Mooij, Ernst J. W.; Hirano, Teruyuki; Kotani, Takayuki; Kawashima, Yui; Masuda, Kento et al. (2021), "First Detection of Hydroxyl Radical Emission from an Exoplanet Atmosphere: High-dispersion Characterization of WASP-33b Using Subaru/IRD", The Astrophysical Journal Letters 910 (1): L9, doi:10.3847/2041-8213/abec71, Bibcode: 2021ApJ...910L...9N 
  16. ↑ 16.0 16.1 Iorio, Lorenzo (2010-07-25), "Classical and relativistic node precessional effects in WASP-33b and perspectives for detecting them", Astrophysics and Space Science 331 (2): 485–496, doi:10.1007/s10509-010-0468-x, Bibcode: 2011Ap&SS.331..485I 
  17. ↑ Borsa, F. et al. (2021), "The GAPS Programme at TNG", Astronomy & Astrophysics 653: A104, doi:10.1051/0004-6361/202140559 



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