HAT-P-11

HAT-P-11, also designated GSC 03561-02092, is an orange dwarf metal rich star about 123 light-years away in the constellation Cygnus. This star is notable for its relatively large rate of proper motion. The magnitude of this star is about 9, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night. The age of this star is about 6.5 billion years.[3]

HAT-P-11
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus[1]
Right ascension 19h 50m 50.2475s[2]
Declination +48° 04′ 51.0973″[2]
Apparent magnitude (V) 9.473[3] 9.59 [4]
Characteristics
Spectral type K4 [4]
Apparent magnitude (B) 10.66±0.05[3]
Apparent magnitude (J) 7.608±0.029[5]
Apparent magnitude (H) 7.131±0.021[5]
Apparent magnitude (K) 7.009±0.020[5]
Astrometry
Proper motion (μ) RA: 125.984±0.041[2] mas/yr
Dec.: 232.988±0.045[2] mas/yr
Parallax (π)26.4508 ± 0.0234[2] mas
Distance123.3 ± 0.1 ly
(37.81 ± 0.03 pc)
Absolute magnitude (MV)6.57±0.09[4]
Details
Mass0.81+0.03
−0.02[4] M☉
Radius0.683±0.009[6] R☉
Luminosity0.26±0.02[4] L☉
Surface gravity (log g)4.59±0.03[4] cgs
Temperature4780±50[4] K
Metallicity [Fe/H]0.31±0.05[4] dex
Rotational velocity (v sin i)1.5±1.5[4] km/s
Age6.5+5.9
−4.1[4] Gyr
Other designations
BD+47°2936, HIP 97657, NLTT 48335, KOI-3, KIC 10748390, GSC 03561-02092[3]
Database references
SIMBADdata
KICdata

The star has active latitudes that generate starspots.[7] The star appears to have a very small radius, which can be explained by the anomalously high helium fraction.[8]

Planetary system
Artist Illustration of planet HAT-P-11b.[9]

An extrasolar planet, was discovered by the HATNet Project using the transit method, believed to be a little larger than the planet Neptune.

That planet orbits out of alignment from the star's spin axis. The system is oblique at 100°.[7] This star system was within the field of view of the Kepler Mission planet-hunter spacecraft.[4]

A trend in the radial velocity measurements taken to confirm the planet indicated a possible additional body in the system.[4] This was confirmed in 2018 when a second planet was detected on an approximately nine year orbit.[10]

The HAT-P-11 planetary system[11][10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 23.4±1.5 M⊕ 0.05254+0.00064
−0.00066		 4.887802443+0.000000034
−0.000000030		 0.218+0.034
−0.031		 89.05+0.15
−0.09°		 4.36±0.06 R⊕
c ≥507+30
−27 M⊕		 4.13+0.29
−0.16		 3407+360
−190		 0.601+0.032
−0.031		 — —

See also

References
  1. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. "BD+47 2936". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-04-22.
  4. Bakos, G. Á.; et al. (2010). "HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field". The Astrophysical Journal. 710 (2): 1724–1745. arXiv:0901.0282. Bibcode:2010ApJ...710.1724B. doi:10.1088/0004-637X/710/2/1724.
  5. Skrutskie, M. F.; et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.Vizier catalog entry
  6. Deming, Drake; et al. (2011). "Kepler and Ground-based Transits of the Exo-Neptune HAT-P-11b". The Astrophysical Journal. 740 (1). 33. arXiv:1107.2977. Bibcode:2011ApJ...740...33D. doi:10.1088/0004-637X/740/1/33.
  7. Sanchis-Ojeda, R.; Winn, J. N.; Fabrycky, D. C. (2012). "Starspots and spin-orbit alignment for Kepler cool host stars". Astronomische Nachrichten. 334 (1–2): 180–183. arXiv:1211.2002. Bibcode:2013AN....334..180S. doi:10.1002/asna.201211765. S2CID 38743202.
  8. A comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars, 2015, arXiv:1503.09111
  9. "Clear skies on exo-Neptune". www.spacetelescope.org. ESA/Hubble. Retrieved 25 September 2014.
  10. Yee, Samuel W.; et al. (2018). "HAT-P-11: Discovery of a Second Planet and a Clue to Understanding Exoplanet Obliquities". The Astronomical Journal. 155 (6). 255. arXiv:1805.09352. Bibcode:2018AJ....155..255Y. doi:10.3847/1538-3881/aabfec.
  11. Huber, K. F.; Czesla, S.; Schmitt, J. H. M. M. (2017). "Discovery of the secondary eclipse of HAT-P-11 b". Astronomy and Astrophysics. 597. A113. arXiv:1611.00153. Bibcode:2017A&A...597A.113H. doi:10.1051/0004-6361/201629699.

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