Discovery [1] | |
---|---|
Discovered by | Bakos et al. |
Discovery site | Cambridge, Massachusetts |
Discovery date | 2 January 2009 |
Transit ( HATNet) | |
Orbital characteristics | |
Apastron | 0.0637+0.0020 −0.0019 AU |
Periastron | 0.0413+0.0018 −0.0019 AU |
0.05254+0.00064 −0.00066 AU | |
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] ME |
Mean
density | 1,440 kg/m3 (2,430 lb/cu yd) |
1.20 g | |
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.
This planet is located approximately 123 light-years (38 pc) distant from Earth. [4]
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]
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 is probably composed primarily of heavy elements with only 10% hydrogen and helium by mass, like
Gliese 436 b.
[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 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 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 intense lightning storms with similar properties as ones on Saturn. [10]
In December 2021 evidence of a magnetosphere was discovered in HAT-P-11b that could be the first ever in any exoplanet. [11] [12] [13]
Media related to HAT-P-11b at Wikimedia Commons