Astronomy:HD 177830
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 05m 20.7732s[1] |
| Declination | +25° 55′ 14.373″[1] |
| Apparent magnitude (V) | 7.175 |
| Characteristics | |
| Spectral type | K0IV[2]/M4V[3] |
| Astrometry | |
| Radial velocity (Rv) | −71.86 ± 0.06[4] km/s |
| Proper motion (μ) | RA: −41.248(12)[1] mas/yr Dec.: −52.580(17)[1] mas/yr |
| Parallax (π) | 16.0063 ± 0.0165[1] mas |
| Distance | 203.8 ± 0.2 ly (62.48 ± 0.06 pc) |
| Details | |
| Mass | 1.48[5] M☉ |
| Radius | 2.99[5] R☉ |
| Surface gravity (log g) | 4.03[5] cgs |
| Temperature | 4948[5] K |
| Metallicity [Fe/H] | 0.55 ± 0.03[6] dex |
| Rotational velocity (v sin i) | 2.54[5] km/s |
| Age | 4.4 ± 2.2[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 177830 is a 7th magnitude binary star system located approximately 205 light-years away in the constellation of Lyra. The primary star is slightly more massive than the 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 204 light years, it is not visible to the unaided eye. With binoculars it should be easily visible.
The primary star is known to have two extrasolar planets orbiting around it.
Stellar system
The secondary star is a Red dwarf star orbiting at a distance of 100 to 200 AU with a likely period of roughly 800 years.[3]
Planetary system
On November 1, 1999,[8] 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 and an analysis on data released by the team performed by amateur astronomer Peter Jalowiczor along with two other planets. This planet is nearly 50% more massive than Jupiter (|♃|J}}}}}}) and takes 407 days to orbit the star in an extremely circular orbit.[2] 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 MJ, 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 (M☉) 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 is in a near 4:1 resonance with the outer planet.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | ≥0.15 ± 0.03 MJ | 0.5137 ± 0.0006 | 110.9 ± 0.3 | 0.3495 ± 0.0002 | — | — |
| b | ≥1.49 ± 0.03 MJ | 1.2218 ± 0.0008 | 406.6 ± 0.4 | 0.009 ± 0.004 | — | — |
See also
- List of exoplanets discovered before 2000 - HD 177830 b
- List of exoplanets discovered in 2010 - HD 177830 c
References
- ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 Vogt, Steven S. et al. (2000). "Six New Planets from the Keck Precision Velocity Survey". The Astrophysical Journal 536 (2): 902–914. doi:10.1086/308981. Bibcode: 2000ApJ...536..902V.
- ↑ 3.0 3.1 Roberts Jr., Lewis C. et al. (2015). "Know the Star, Know the Planet. V. Characterization of the Stellar Companion to the Exoplanet Host Star HD 177830". The Astronomical Journal 150 (4). doi:10.1088/0004-6256/150/4/103. Bibcode: 2015AJ....150..103R.
- ↑ Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics 574: A50. doi:10.1051/0004-6361/201424474. Bibcode: 2015A&A...574A..50J.
- ↑ 5.0 5.1 5.2 5.3 5.4 Fischer, Debra A.; Valenti, Jeff (2005). "The Planet-Metallicity Correlation". The Astrophysical Journal 622 (2): 1102. doi:10.1086/428383. Bibcode: 2005ApJ...622.1102F.
- ↑ 6.0 6.1 6.2 6.3 Meschiari, Stefano et al. (2011). "The Lick-Carnegie Survey: Four New Exoplanet Candidates". The Astrophysical Journal 727 (2). doi:10.1088/0004-637X/727/2/117. Bibcode: 2011ApJ...727..117M.
- ↑ "HD 177830 -- Double or multiple star". Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+177830.
- ↑ "Astronomers discover six new planets orbiting nearby stars" (Press release). Kamuela, Hawaii: W. M. Keck Observatory. November 1, 1999. Retrieved December 19, 2017.
Coordinates: 
19h 05m 20.7735s, +25° 55′ 14.379″
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