HD 80606 b

Discovery

The variable radial velocity of HD 80606 was first noticed in 1999 from observations with the 10-m Keck 1 telescope at the W. M. Keck Observatory in Hawaii by the G-Dwarf Planet Search, a survey of nearly 1000 nearby G dwarfs to identify extrasolar planet candidates. The star was then followed up by the Geneva Extrasolar Planet Search team using the ELODIE spectrograph mounted on the 1.93-m telescope at the Haute-Provence Observatory. The discovery of HD 80606 b was announced on 4 April 2001.

The transit was detected using a Celestron 35-cm Schmidt–Cassegrain telescope at the UCL Observatory. Prior to the large data release of the Kepler Mission in February 2011, HD 80606 b had the longest orbital period of any known transiting planet. It takes 12.1 hours to transit its star.

The transit of 14 January 2010 was partially observed by MOST; but there were equipment failures over part of this time, and the 8 January secondary transit was entirely lost. The midpoint of the next transit was 1 February 2013 11:37 UT.

Physical properties

HD 80606 b has the most eccentric orbit of any known planet after HD 20782 b. Its eccentricity is 0.9336, comparable to Halley's Comet. The eccentricity may be a result of the Kozai mechanism, which would occur if the planet's orbit is significantly inclined to that of the binary stars. This interpretation is supported by measurements of the Rossiter–McLaughlin effect, which indicate that the planet's orbit may be significantly inclined (by 42°) to the rotational axis of the star, a configuration which would be expected if the Kozai mechanism were responsible for the orbit.

As a result of this high eccentricity, the planet's distance from its star varies from 0.03 to 0.88 AU. At apastron it would receive an insolation similar to that of Earth, while at periastron the insolation would be around 800 times greater, far more than that experienced by Mercury in the Solar System. In 2009, the eclipse of HD 80606 b by its parent star was detected, allowing measurements of the planet's temperature to be made as the planet passed through periastron. These measurements indicated that the temperature rose from around 800 K to 1500 K in just 6 hours.

An observer above the cloud tops of the gas giant would see the parent star swell to 30 times the apparent size of the Sun in our own sky.

The planet's rotation period has been measured to be hours, longer than the predicted pseudo-synchronous rotation period of 40 hours.

Weather

The planet has wild variations in its weather as it orbits its parent star. Computer models predict the planet heats up 555 K in just a matter of hours, triggering "shock wave storms" that ripple out from the point facing its star, with winds that move at around 5 km/s.

Notes

References

References

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2. [http://var2.astro.cz/ETD/predict_detail.php?STARNAME=HD80606&PLANET=b&PER=&M= HD 80606 Transit Times – Variable Star and Exoplanets]
3. Albrecht, Simon. (30 August 2012). "Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments". [[The Astrophysical Journal]].
4. Pont, F.. (August 2009). "Spin-orbit misalignment in the HD 80606 planetary system". [[Astronomy & Astrophysics]].
5. (4 April 2001). "Exoplanets: The Hunt Continues!". [[European Southern Observatory]].
6. Naef, D.. (August 2001). "HD 80606 b, a planet on an extremely elongated orbit". [[Astronomy & Astrophysics]].
7. Laughlin, Gregory. (January 2009). "Rapid heating of the atmosphere of an extrasolar planet". [[Nature (journal).
8. Moutou, C.. (April 2009). "Photometric and spectroscopic detection of the primary transit of the 111-day-period planet HD 80 606 b". [[Astronomy & Astrophysics]].
9. Fossey, Stephen J.. (June 2009). "Detection of a transit by the planetary companion of HD 80606". [[Monthly Notices of the Royal Astronomical Society]].
10. (21 April 2009). "RAS PN 09/23 (NAM 10): London students find Jupiter-sized oddball planet". The Royal Astronomical Society.
11. (28 January 2009). "Exoplanet Sees Extreme Heat Waves". [[Space.com]].
12. Hidas, M. G.. (2010). "An ingress and a complete transit of HD 80606 b". Monthly Notices of the Royal Astronomical Society.
13. Roberts, Jessica E.. (2013). "MOST Space Telescope Photometry of the 2010 January Transit of Extrasolar Planet HD80606b". [[The Astrophysical Journal]].
14. de Wit. (April 2016). "Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere". [[The Astrophysical Journal Letters]].
15. Bonomo, A. S.. (June 2017). "The GAPS Programme with HARPS-N at TNG: XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". [[Astronomy & Astrophysics]].