HD 177830

HD 177830
Observation data
Epoch 2000      Equinox 2000
Constellation Lyra
Right ascension 19h 05m 20.7735s
Declination +25° 55′ 14.379″
Apparent magnitude (V) 7.175
Absolute magnitude (V) 3.319
Distance 192.54 ly
(59.06 pc)
Spectral type K0 IV
Other designations
BD+25°3719, Gliese 743.2, GSC 02126-01196, HIP 93746, SAO 86791
Database references
SIMBAD data
ARICNS data
Extrasolar Planets
Encyclopaedia		 data

HD 177830 is a 7th magnitude star located approximately 190 light-years away in the constellation of Lyra. It is slightly more massive than our Sun, but cooler being a type K star. Therefore it is a subgiant clearly more evolved than the Sun. In visual light it is four times brighter than the Sun, but because of its distance, about 190 light years, it is not visible to the unaided eye. With binoculars it should be easily visible.

The star is known to have two extrasolar planets orbiting around it.

Contents

Planetary system

On November 14, 1999, the discovery of a planet HD 177830 b was announced by the California and Carnegie Planet Search team using the very successful radial velocity method along with two other planets. This planet is nearly 50% more massive than Jupiter and takes 407 days to orbit the star in an extremely circular orbit.[1] In 2000 a group of scientists proposed, based on preliminary Hipparcos astrometrical satellite data, that the orbital inclination of HD 177830 b is as little as 1.3°. If that was the case, the planet would have a mass of 67 times that of Jupiter making it a brown dwarf instead of a planet. However, it is very unlikely that the planet would have such orbit. Furthermore, brown dwarfs with short orbits around solar-mass stars are exceedingly rare (the so-called "brown dwarf desert") making the claim even more unlikely.

On November 17, 2010, the discovery of a second planet HD 177830 c was announced along with four other planets. The planet has 50% the mass of Saturn and takes 111 days to orbit the star in a very eccentric orbit. This planet would be close to a 1:4 resonance with the outer planet.[2]

The HD 177830 system[2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity
b ≥1.49 ± 0.03 MJ 1.2218 ± 0.0008 406.6 ± 0.4 0.009 ± 0.004
c ≥0.15 ± 0.03 MJ 0.5137 ± 0.0006 110.9 ± 0.3 0.3495 ± 0.0002

See also

References

  1. ^ Vogt et al.; Marcy, Geoffrey W.; Butler, R. Paul; Apps, Kevin (2000). "Six New Planets from the Keck Precision Velocity Survey". The Astrophysical Journal 536 (2): 902–914. arXiv:astro-ph/9911506. Bibcode 2000ApJ...536..902V. doi:10.1086/308981. http://www.iop.org/EJ/article/0004-637X/536/2/902/50799.html. 
  2. ^ a b Meschiari et al. (2011). "The Lick-Carnegie Survey: Four New Exoplanet Candidates". arXiv:1011.4068 [astro-ph.EP]. 

External links

Coordinates: 19h 05m 20.7735s, +25° 55′ 14.379″