HD 188015
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vulpecula
Right ascension 19h 52m 04.5430s[1]
Declination +28° 06′ 01.3417″[1]
Apparent magnitude (V) 8.24[2]
Characteristics
Spectral type G5IV[3]
B−V color index 0.727±0.010[2]
Astrometry
Radial velocity (Rv)+0.28±0.14[1] km/s
Proper motion (μ) RA: 52.544±0.064[1] mas/yr
Dec.: −91.934±0.058[1] mas/yr
Parallax (π)19.7065 ± 0.0422 mas[1]
Distance165.5 ± 0.4 ly
(50.7 ± 0.1 pc)
Absolute magnitude (MV)4.47[2]
Details
Mass1.08±0.02[4] M☉
Radius1.21±0.03[4] R☉
Luminosity1.41±0.03[4] L☉
Surface gravity (log g)4.30±0.03[4] cgs
Temperature5,726±28[5] K
Metallicity [Fe/H]0.27±0.02[5] dex
Rotational velocity (v sin i)5.0[6] km/s
Age5.9±1.3[4] Gyr
Other designations
BD+27 3539, HIP 97769, 2MASS J19520455+2806015[7]
Database references
SIMBADdata

HD 188015 is a yellow-hued star with an exoplanetary companion in the northern constellation of Vulpecula. It has an apparent visual magnitude of 8.24,[2] making it an 8th magnitude star, and thus is too faint to be readily visible to the naked eye. The distance to this star can be estimated through parallax measurements, which yield a separation of 165.5 light years from the Sun.[1]

This star was assigned a stellar classification of G5IV by J. F. Heard in 1956,[3] matching the spectrum of an evolving G-type subgiant star. This suggests it has ceased or is about to stop hydrogen fusion in its core. The absolute magnitude of 4.47[2] lies just above the main sequence.[8] It is estimated to be six[4] billion years old and is chromospherically quiet with a projected rotational velocity of 5 km/s.[6] The star is almost twice as metal-rich as the Sun. It has 1.1 times the mass and 1.2 times the radius of the Sun. HD 188015 is radiating 1.4[4] times the luminosity of the Sun from its photosphere at an effective temperature of 5,726 km/s.[5]

Companions

A stellar common proper motion candidate was announced in 2006 and designated HD 188015 B. It is located at an angular separation of 13″ along a position angle of 85°. The photometric distance estimate for this object is 153 ± 31 ly (46.9 ± 9.5 pc), matching the primary within the margin of error. They have a projected separation of 684 AU.[9]

A Jovian planetary companion to this star was announced in 2005, based on radial velocity measurements indicating a periodic perturbation. It is orbiting the host star at a distance of 1.2 AU with a period of 1.26 years and an eccentricity (ovalness) of 0.14. The inclination of the orbital plane remains unknown, so only a lower bound on the planet's mass can be determined. It has a minimum mass equal to 1.5 times the mass of Jupiter.[8] The orbital path of this object intersects the habitable zone of the star, which is likely to eject any Earth-like planet from that region.[10]

The HD 188015 planetary system[8]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >1.50 ± 0.13 MJ 1.203 ± 0.070 461.2 ± 1.7 0.137 ± 0.026 — —

See also

References

  1. 1 2 3 4 5 6 7 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.
  2. 1 2 3 4 5 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.
  3. 1 2 Heard, John Frederick (1956). "The radial velocities, spectral classes and photographic magnitudes of 1041 late-type stars". Publications of the David Dunlap Observatory. University of Toronto, Toronto, Canada: University of Toronto Press. 2 (4): 107–143. Bibcode:1956PDDO....2..107H.
  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 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.
  6. 1 2 Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744. 21.
  7. ↑ "HD 188015". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-10-21.
  8. 1 2 3 Marcy, Geoffrey W.; et al. (2005). "Five New Extrasolar Planets". The Astrophysical Journal. 619 (1): 570–584. Bibcode:2005ApJ...619..570M. CiteSeerX 10.1.1.516.6667. doi:10.1086/426384.
  9. ↑ Raghavan, Deepak; et al. (July 2006). "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems". The Astrophysical Journal. 646 (1): 523–542. arXiv:astro-ph/0603836. Bibcode:2006ApJ...646..523R. doi:10.1086/504823. S2CID 5669768.
  10. ↑ Yeager, K. E.; et al. (January 2011). "On the ejection of Earth-mass planets from the habitable zones of the solar twins HD 20782 and HD 188015". International Journal of Astrobiology. 10 (1): 1–13. Bibcode:2011IJAsB..10....1Y. doi:10.1017/S1473550410000145. S2CID 119625844.
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