HD 154857

HD 154857
Observation data
Epoch J2000      Equinox ICRS
Constellation Ara
Right ascension 17h 11m 15.72205s
Declination −56° 40′ 50.8712″
Apparent magnitude (V) 7.25
Characteristics
Evolutionary stage subgiant
Spectral type G5IV-V
B−V color index 0.699±0.001
Variable type Constant
Astrometry
Radial velocity (Rv)+28.10±0.12 km/s
Proper motion (μ) RA: +87.442 mas/yr
Dec.: −55.861 mas/yr
Parallax (π)15.8176±0.0197 mas
Distance206.2 ± 0.3 ly
(63.22 ± 0.08 pc)
Absolute magnitude (MV)3.07
Details
Mass1.718+0.03
−0.022 M☉
Radius2.1±0.1 R☉
Luminosity4.4±0.3 L☉
Surface gravity (log g)3.83±0.03 cgs
Temperature5,740±46 K
Metallicity [Fe/H]−0.26±0.01 dex
Rotational velocity (v sin i)1.44±0.50 km/s
Age5.8±0.5 Gyr
Other designations
CD−56°6717, CPD−56°8059, GC 23146, HD 154857, HIP 84069, SAO 244491, PPM 345752, TYC 8735-1682-1, GSC 08735-01682
Database references
SIMBADdata

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. The star is located at a distance of 206 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +28 km/s.

This is a G-type star with a stellar classification of G5IV-V. The absolute magnitude of this star is two magnitudes above the main sequence, which suggests that the star is evolving toward the subgiant stage. It is a metal-poor thin disk star approximately six billion years old and is chromopherically quiet although not in a Maunder Minimum state. 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.

Planetary system

The discovery of one confirmed and one unconfirmed Jovian exoplanet was reported in 2004 and 2007 respectively. The first 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.

The HD 154857 planetary system
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

References

  1. 1 2 3 4 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 6 7 8 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 McCarthy, Chris; et al. (2004). "Multiple Companions to HD 154857 and HD 160691". The Astrophysical Journal. 617 (1): 575–579. arXiv:astro-ph/0409335. Bibcode:2004ApJ...617..575M. doi:10.1086/425214. S2CID 119446133.
  4. 1 2 3 4 5 6 7 Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  5. 1 2 3 Wittenmyer, Robert A.; et al. (March 2014). "The Anglo-Australian Planet Search. XXIII. Two New Jupiter Analogs". The Astrophysical Journal. 783 (2): 9. arXiv:1401.5525. Bibcode:2014ApJ...783..103W. doi:10.1088/0004-637X/783/2/103. S2CID 14082923. 103.
  6. ↑ Sousa, S. G.; et al. (November 2018). "SWEET-Cat updated. New homogenous spectroscopic parameters". Astronomy & Astrophysics. 620: 13. arXiv:1810.08108. Bibcode:2018A&A...620A..58S. doi:10.1051/0004-6361/201833350. S2CID 119374557. A58.
  7. 1 2 Butler, R. P.; et al. (December 2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.
  8. ↑ "HD 154857". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-10.
  9. ↑ Gonzalez, Guillermo (October 2009). "Stars with planets and the thick disc". Monthly Notices of the Royal Astronomical Society: Letters. 399 (1): L103–L107. Bibcode:2009MNRAS.399L.103G. doi:10.1111/j.1745-3933.2009.00734.x.
  10. ↑ 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. S2CID 118958847.