Astronomy:HD 154857
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h 11m 15.72180s[1] |
| Declination | −56° 40′ 50.8706″[1] |
| Apparent magnitude (V) | 7.25[2] |
| Characteristics | |
| Spectral type | G5IV-V[3] |
| B−V color index | 0.699±0.001[2] |
| Variable type | Constant[4] |
| Astrometry | |
| Radial velocity (Rv) | +28.06±0.15[1] km/s |
| Proper motion (μ) | RA: 87.585[1] mas/yr Dec.: −55.891[1] mas/yr |
| Parallax (π) | 15.7321 ± 0.0385[1] mas |
| Distance | 207.3 ± 0.5 ly (63.6 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.07[3] |
| Details | |
| Mass | 1.718+0.03 −0.022[5] M☉ |
| Radius | 2.1±0.1[4] R☉ |
| Luminosity | 4.4±0.3[4] L☉ |
| Surface gravity (log g) | 3.83±0.03[4] cgs |
| Temperature | 5,740±46[4] K |
| Metallicity [Fe/H] | −0.26±0.01[6] dex |
| Rotational velocity (v sin i) | 1.44±0.50[7] km/s |
| Age | 5.8±0.5[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 154857 is a star with two exoplanetary companions in the southern constellation of Ara. It is too dim to be visible with the naked eye having an apparent visual magnitude of 7.25.[2] The star is located at a distance of 207 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +28 km/s.[1]
This is a G-type star with a stellar classification of G5IV-V.[3] The absolute magnitude of this star is two magnitudes above the main sequence, which suggests that the star is evolving toward the subgiant stage.[3] It is a metal-poor thin disk star[9] approximately six billion years old and is chromopherically quiet although not in a Maunder Minimum state.[4] The star is larger, more massive, and more luminous than the Sun. It is spinning with a projected rotational velocity of 1.4 km/s.[7]
Planetary system
The discovery of one confirmed and one unconfirmed Jovian exoplanet was reported in 2004[3] and 2007[10] respectively. The former planet HD 154857 b has mass >1.8 times that of Jupiter. It orbits the star 20% further than Earth-Sun distance, taking 409 days with 47% eccentricity. The additional object (HD 154857 c) was confirmed as a planetary companion in January 2014.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥ 2.24±0.05 MJ | 1.291±0.008 | 408.6±0.5 | 0.06±0.05 | — | — |
| c | ≥ 2.58±0.16 MJ | 5.36±0.09 | 3,452±105 | 0.06±0.05 | — | — |
See also
- List of extrasolar planets
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 3.3 3.4 McCarthy, Chris et al. (2004). "Multiple Companions to HD 154857 and HD 160691". The Astrophysical Journal 617 (1): 575–579. doi:10.1086/425214. Bibcode: 2004ApJ...617..575M.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics 585: 14. doi:10.1051/0004-6361/201527297. A5. Bibcode: 2016A&A...585A...5B.
- ↑ 5.0 5.1 5.2 Wittenmyer, Robert A. et al. (March 2014). "The Anglo-Australian Planet Search. XXIII. Two New Jupiter Analogs". The Astrophysical Journal 783 (2): 9. doi:10.1088/0004-637X/783/2/103. 103. Bibcode: 2014ApJ...783..103W.
- ↑ Sousa, S. G. et al. (November 2018). "SWEET-Cat updated. New homogenous spectroscopic parameters". Astronomy & Astrophysics 620: 13. doi:10.1051/0004-6361/201833350. A58. Bibcode: 2018A&A...620A..58S.
- ↑ 7.0 7.1 Butler, R. P. et al. (December 2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. doi:10.1086/504701. Bibcode: 2006ApJ...646..505B.
- ↑ "HD 154857". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+154857.
- ↑ Gonzalez, Guillermo (October 2009). "Stars with planets and the thick disc". Monthly Notices of the Royal Astronomical Society: Letters 399 (1): L103–L107. doi:10.1111/j.1745-3933.2009.00734.x. Bibcode: 2009MNRAS.399L.103G.
- ↑ O'Toole, Simon J. et al. (2007). "New Planets around Three G Dwarfs". The Astrophysical Journal 660 (2): 1636–1641. doi:10.1086/513563. Bibcode: 2007ApJ...660.1636O.
External links
- "HD 154857". Extrasolar Planets Encyclopaedia. http://exoplanet.eu/star.php?st=HD+154857. Retrieved 2008-07-21.
- http://planetquest.jpl.nasa.gov
Coordinates: 
17h 11m 15.7219s, −56° 40′ 50.865″
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