_compared_to_Exoplanet_HAT-P-11b.png) Size comparison of Neptune with HAT-P-11b (gray). | |
| Discovery[1] | |
|---|---|
| Discovered by | Bakoset al. |
| Discovery site | Cambridge, Massachusetts |
| Discovery date | 2 January 2009 |
| Transit (HATNet) | |
| Orbital characteristics | |
| Apastron | 0.0637+0.0020 −0.0019AU |
| Periastron | 0.0413+0.0018 −0.0019AU |
| 0.05254+0.00064 −0.00066AU | |
| Eccentricity | 0.218+0.034 −0.031[2] |
| 4.887802443+0.000000034 −0.000000030[3]d | |
| Inclination | 89.05+0.15 −0.09[3] |
| 2454957.15+0.17 −0.20[2] | |
| 19+14 −16[2] | |
| Semi-amplitude | 10.42+0.64 −0.66[2] |
| Star | HAT-P-11 |
| Physical characteristics | |
| 4.36±0.06[3]R🜨 | |
| Mass | 23.4±1.5[2]M🜨 |
Meandensity | 1.44 g/cm3 |
| 1.20g | |
HAT-P-11b (orKepler-3b) is anextrasolar planet orbiting the starHAT-P-11. It was discovered by theHATNet Project team in 2009 using thetransit method, and submitted for publication on 2 January 2009.
This planet is located approximately 123light-years (38 pc) distant from Earth.[4]
The HATNet Project team initially detected thetransits 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 50radial velocity measurements taken with the HIRES radial velocity spectrometer atW. 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 initialfield of view of theKepler 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]
This planet orbits about the same distance from the star asDimidium is fromHelvetios, typical of transiting planets. However, the orbit of this planet is eccentric, at around 0.198, unusually high forhot 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 is probably composed primarily of heavy elements with only 10% hydrogen and helium by mass, likeAwohali.[1]
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 timemolecules, namelywater 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 unpolarized radio signal coming from the exoplanet, but it was not observed in a repeat observation in 2010.[9] If the signal was real, then it was probably due to intenselightning storms with similar properties as ones onSaturn.[10]
In December 2021 evidence of amagnetosphere was discovered in HAT-P-11b that could be the first ever in any exoplanet.[11][12][13]
Media related toHAT-P-11b at Wikimedia Commons
