HD 159868 is a star in the southern constellation of Scorpius, positioned about 0.3° to the ESE of the bright star Theta Scorpii.[9] With an apparent visual magnitude of +7.24,[3] it is too faint to be visible to the naked eye but can be viewed with a small telescope. The star lies at a distance of 183 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −24 km/s.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 17h 38m 59.5264s[2] |
| Declination | −43° 08′ 43.8443″[2] |
| Apparent magnitude (V) | +7.24[3] |
| Characteristics | |
| Spectral type | G5V[4] |
| Apparent magnitude (J) | 5.941±0.021[5] |
| Apparent magnitude (H) | 5.567±0.026[5] |
| Apparent magnitude (K) | 5.535±0.024[5] |
| B−V color index | 0.714±0.012[3] |
| Astrometry | |
| Radial velocity (Rv) | −23.80±0.76[3] km/s |
| Proper motion (μ) | RA: −230.510[2] mas/yr Dec.: −167.766[2] mas/yr |
| Parallax (π) | 17.8763 ± 0.0530 mas[2] |
| Distance | 182.5 ± 0.5 ly (55.9 ± 0.2 pc) |
| Absolute magnitude (MV) | +3.63[6] |
| Details[6] | |
| Mass | 1.087+0.032 −0.033 M☉[6] 1.123±0.018[7] M☉ |
| Radius | 1.97±0.04 R☉[7] 2.03+0.05 −0.04[2] R☉ |
| Luminosity | 3.59±0.02[2] L☉ |
| Surface gravity (log g) | 3.96±0.02 cgs |
| Temperature | 5,558±15 K |
| Metallicity [Fe/H] | −0.08±0.01 dex |
| Rotational velocity (v sin i) | 2.1 km/s |
| Age | 6.6±0.2[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of this object matches a G-type main-sequence star with a stellar classification of G5V. It has a relatively low surface gravity for its class, which suggests it is slightly evolved off the main sequence. The star is chromospherically inactive with a slow rotation rate, having a projected rotational velocity of 2.1 km/s.[6] It is an estimated 6.6[7] billion years old with 8–12% more mass than the Sun and nearly double the Sun's radius. The star is radiating 3.6 times the luminosity of the Sun from its photosphere at an effective temperature of 5,558 K.[2]
Planetary system
editIn 2007, a planet of the star was announced by astronomer Simon J. O'Toole and collaborators.[10] The planet (designated HD 159868 b) is likely to be a gas giant. Preliminary orbital elements suggested the orbit is extremely eccentric at the average distance of 2 astronomical units (AU), ranging as close as 0.62 AU to as far as 3.38 AU. In 2012, a second planet of the star was announced by astronomer Robert A. Wittenmyer and associates. The orbit of the first planet was significantly revised during the investigation.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | ≥0.73±0.05 MJ | 1.00±0.01 | 352.3±1.3 | 0.15±0.05 | — | — |
| b | ≥2.1±0.1 MJ | 2.25±0.03 | 1,178.4±8.8 | 0.01±0.03 | — | — |
See also
editReferences
edit- ^ 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
- ^ a b c d e f g h 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.
- ^ a b c d e Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ Houk, N. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 2. Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
- ^ a b c Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN 0004-6256. S2CID 18913331. Vizier catalog entry
- ^ a b c d e f Wittenmyer, Robert A.; et al. (2012). "The Anglo-Australian Planet Search. XXII. Two New Multi-planet Systems". The Astrophysical Journal. 753 (2): 169. arXiv:1205.2765. Bibcode:2012ApJ...753..169W. doi:10.1088/0004-637X/753/2/169. S2CID 2941264.
- ^ a b c d Delgado Mena, E.; et al. (April 2019). "Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]". Astronomy & Astrophysics. 624: 24. arXiv:1902.02127. Bibcode:2019A&A...624A..78D. doi:10.1051/0004-6361/201834783. S2CID 90259810. A78.
- ^ "HD 159868". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-10.
- ^ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 3. Sky Publishing Corporation and the European Space Agency. p. 1460. ISBN 0-933346-84-0.
- ^ a b O'Toole, Simon J.; et al. (2007). "New Planets around Three G Dwarfs". The Astrophysical Journal. 660 (2): 1636–1641. arXiv:astro-ph/0702213. Bibcode:2007ApJ...660.1636O. doi:10.1086/513563.
External links
edit- "HD 159868". Exoplanets. Archived from the original on 2008-05-14. Retrieved 2008-07-19.
- "Notes for star HD 159868". Extrasolar Planets Encyclopaedia. Archived from the original on July 2, 2007. Retrieved 2008-07-19.