astro.wikisort.org - Meteorite

HAT-P-11b (or Kepler-3b) is an extrasolar planet orbiting the star HAT-P-11. It was discovered by the HATNet Project team in 2009 using the transit method, and submitted for publication on 2 January 2009.

HAT-P-11b / Kepler-3b

Size comparison of Neptune with HAT-P-11b (gray).
Discovery[1]
Discovered by	Bakos et al.
Discovery site	Cambridge, Massachusetts
Discovery date	2 January 2009
Detection method	Transit (HATNet)
Orbital characteristics
Apastron	0.0637+0.0020 −0.0019 AU
Periastron	0.0413+0.0018 −0.0019 AU
Semi-major axis	0.05254+0.00064 −0.00066 AU
Eccentricity	0.218+0.034 −0.031[2]
Orbital period (sidereal)	4.887802443+0.000000034 −0.000000030[3] d
Inclination	89.05+0.15 −0.09[3]
Time of periastron	2454957.15+0.17 −0.20[2]
Argument of periastron	19+14 −16[2]
Semi-amplitude	10.42+0.64 −0.66[2]
Star	HAT-P-11
Physical characteristics
Mean radius	4.36±0.06[3] REarth
Mass	23.4±1.5[2] MEarth
Mean density	1,440 kg/m3 (2,430 lb/cu yd)
Surface gravity	1.20 g

This planet is located approximately 123 light-years (38 pc) distant from Earth.[4]

Discovery

The HATNet Project team initially detected the transits of HAT-P-11b from analysis of 11470 images, taken in 2004 and 2005, by the HAT-6 and HAT-9 telescopes. The planet was confirmed using 50 radial velocity measurements taken with the HIRES radial velocity spectrometer at W. M. Keck Observatory.[1]

At the time of its discovery HAT-P-11b was the smallest radius transiting extrasolar planet discovered by a ground based transit search and was also one of three previously known transiting planets within the initial field of view of the Kepler spacecraft.[1]

There was a linear trend in the radial velocities indicating the possibility of another planet in the system.[1] This planet, HAT-P-11c, was confirmed in 2018.[2]

Characteristics

This planet orbits about the same distance from the star as 51 Pegasi b is from 51 Pegasi, typical of transiting planets. However, the orbit of this planet is eccentric, at around 0.198, unusually high for hot Neptunes. HAT-P-11b's orbit is also highly inclined, with a tilt of 103⁺²⁶
₋₁₀°.[5] degrees relative to its star's rotation.[6][7]

The planet fits models for 90% heavy elements^{[clarification needed]}. Expected temperature is 878 ± 15K.[1] Actual temperature must await calculations of secondary transit.

On 24 September 2014, NASA reported that HAT-P-11b is the first Neptune-sized exoplanet known to have a relatively cloud-free atmosphere and, as well, the first time molecules, namely water vapor, of any kind have been found on such a relatively small exoplanet.[8] In 2009 French astronomers observed what was thought to be a weak radio signal coming from the exoplanet. In 2016 scientists from the University of St Andrews set out to solve the mystery. They assumed that the signal was real and was coming from the planet and investigated whether it can be produced by lightning on HAT-P-11b. Assuming that the underlying physics of lightning is the same for all Solar System planets, like Earth and Saturn, as well as on HAT-P-11b, the researchers found that 3.8 × 10^6 lightning flashes of Saturnian lightning-strength in a square kilometre per hour would explain the observed radio signal on HAT-P-11b. This storm would have been so enormous that the largest thunderstorms on Earth or Saturn would have produced <1% of the strength of the signal coming from the planet.[9][10]

In December 2021 a magnetosphere was discovered in HAT-P-11b, the first ever in any exoplanet.[11][12]

See also

• Gliese 436 b
• HATNet Project
• HAT-P-7b
• Kepler Mission

References

External links

Media related to HAT-P-11b at Wikimedia Commons

• "HAT-P-11 b". Exoplanets. Archived from the original on 18 March 2012. Retrieved 1 February 2009.

На других языках

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[de] HAT-P-11b

HAT-P-11b ist ein Exoplanet im Sternbild Schwan. Er ist der bislang (Stand September 2014) kleinste bekannte Exoplanet mit Wasserdampf in seiner Atmosphäre und wurde im Rahmen des HATNet Projects entdeckt. HAT-P-11b hat ungefähr den vierfachen Erddurchmesser, ist somit etwa so groß wie Neptun und rund 124 Lichtjahre von der Erde entfernt.[1][2]

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- [en] HAT-P-11b

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[es] HAT-P-11b

HAT-P-11b es un planeta extrasolar que orbita alrededor de la estrella HAT-P-11. El descubrimiento de este planeta se realizó a través del método de tránsito y fue presentado para su publicación el 2 de enero de 2009. Está situado a unos 123 años luz (38 pc) de distancia, en la constelación de Cygnus, y su estrella madre tiene una luminosidad de 10.ª magnitud, y pertenece al tipo espectral K. Fue el planeta más pequeño conocido en tránsito en el momento de su descubrimiento, con una masa de 26 veces mayor que la Tierra y un radio 4,58 veces mayor. Gira a una distancia similar a la de 51 Pegasi b alrededor de su estrella 51 Pegasi, típico de los planetas descubierto mediante el tránsito. Sin embargo, la órbita de este es bastante excéntrica, en torno a 0,198, inusualmente alto para un mundo del tipo Neptuno caliente. El sistema HAT-P-11 se encuentra en estos momentos dentro del campo visual de la nave espacial de la misión Kepler.[1]

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[ru] HAT-P-11 b

HAT-P-11 b (или Kepler-3 b) — экзопланета, вращающаяся вокруг звезды HAT-P-11. Планета была открыта транзитным методом. Открытие было опубликовано 2 января 2009 года.

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