HD 178911

HD 178911
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 19h 09m 04.35193s[1]
Declination +34° 36′ 01.2420″[1]
Apparent magnitude (V) 6.70[2] (6.89 + 8.96 + 7.88)[3]
Characteristics
HD 178911 Aa/Ab
Evolutionary stage Main sequence
Spectral type G1V + K1V[4]
B−V color index 0.643±0.007[2]
HD 178911 B
Spectral type G5V[5]
B−V color index 0.750±0.015[2]

...

Astrometry
HD 178911 Aa/Ab
Radial velocity (Rv)−38.09±1.01[1] km/s
Proper motion (μ) RA: 76.618[1] mas/yr
Dec.: 207.126[1] mas/yr
Parallax (π)20.2306 ± 0.3846 mas[1]
Distance161 ± 3 ly
(49.4 ± 0.9 pc)
Absolute magnitude (MV)3.28[2]
HD 178911 B
Radial velocity (Rv)−40.324±0.0012[6] km/s
Proper motion (μ) RA: 57.177[7] mas/yr
Dec.: 195.900[7] mas/yr
Parallax (π)24.3775 ± 0.0274 mas[7]
Distance133.8 ± 0.2 ly
(41.02 ± 0.05 pc)
Absolute magnitude (MV)4.90[2]
Orbit[4]
PrimaryHD 178911 Aa
CompanionHD 178911 Ab
Period (P)1,296.984±0.355 d yr
Semi-major axis (a)0.074±0.002″
Eccentricity (e)0.597±0.003
Inclination (i)147.29±0.99°
Longitude of the node (Ω)276.91±1.45°
Argument of periastron (ω)
(secondary)		83.88±0.87°
Semi-amplitude (K1)
(primary)		6.47±0.09 km/s
Semi-amplitude (K2)
(secondary)		8.33±0.18 km/s
Details
HD 178911 Aa
Mass0.802±0.055 M☉[4]
1.234±0.027[8] M☉
HD 178911 Ab
Mass0.622±0.053 M☉[4]
0.942±0.021[8] M☉
HD 178911 B
Mass 1.03±0.02 M☉[9]
Radius 1.05±0.02 R☉[9]
Luminosity 1.00±0.02 L☉[9]
Surface gravity (log g) 4.40±0.02 cgs[9]
Temperature 5,642±29 K[9]
Metallicity [Fe/H] 0.23[10]
Rotational velocity (v sin i) 4.6[10]
Age 4.8±1.3 Gyr[9]
Other designations
STF2747, HD 178911, HR 7272, WDS 19091+3436[11]
HD 178911 A: BD+34 3439, HIP 94076, SAO 67879, PPM 82386, LTT 15608, NLTT 47474[11]
HD 178911 B: BD+34 3438, HIP 94075, SAO 67875, PPM 82385, LTT 15608, NLTT 47473[12]
Database references
SIMBADdata

HD 178911 is a triple star system with an exoplanetary companion in the northern constellation of Lyra. With a combined apparent visual magnitude of 6.70,[2] it is a challenge to view with the naked eye. The system is located at a distance of approximately 161 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −38 km/s.[1]

Stellar system

A companion star, designated component B, was first reported by F. G. W. Struve in 1823. As of 2019, the two have an angular separation of 16.0″ along a position angle of 263°.[3] Component B shares a common motion through space with the primary, and thus they form a wide binary.[13] This secondary is a magnitude 7.88[3] G-type main-sequence star with a stellar classification of G5V.[5] The physical properties of this star are similar to the Sun, although it has a higher metallicity.[9][10]

In 1985, the primary was determined to be a spectroscopic binary pair using the CHARA speckle interferometry program.[14] Designated components Aa and Ab, these have an orbital period of 3.55 yr and an eccentricity (ovalness) of 0.6.[4] They are magnitude 6.89 and 8.96.[3] Based on based on a combined class of G5V for the pair,[8] they have derived main sequence stellar classifications of G1V and K1V, respectively.[4] C. D. Farrington and associates (2014) found dynamic masses for the components of 0.80 and 0.62, respectively.[4] However, based on the classes, the expected masses should be around 1.0 and 0.8. Manuel Andrade (2019) derived higher dynamic masses of 1.20 and 0.94.[8]

An additional companion HD 178911 C is a chance optical alignment and is not part of the system.[4]

Planetary system

In 2001 an extrasolar planet was discovered in orbit around HD 178911 B.[15][13]

The HD 178911 B planetary system[16]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b >7.35 ± 0.60 MJ 0.345 ± 0.20 71.511 ± 0.011 0.139 ± 0.014 — —

See also

References

  1. ^ a b c d e f g 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. ^ a b c d e f 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. ^ a b c d Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  4. ^ a b c d e f g h Farrington, C. D.; et al. (2014). "Separated Fringe Packet Observations with the CHARA Array. II. omega Andromeda, HD 178911, and xi Cephei" (PDF). The Astronomical Journal. 148 (3). 48. arXiv:1407.0639. Bibcode:2014AJ....148...48F. doi:10.1088/0004-6256/148/3/48. S2CID 12909818. Archived from the original (PDF) on 2014-10-16.
  5. ^ a b France, Kevin; et al. (November 2018). "Far-ultraviolet Activity Levels of F, G, K, and M Dwarf Exoplanet Host Stars". The Astrophysical Journal Supplement Series. 239 (1): 24. arXiv:1809.07342. Bibcode:2018ApJS..239...16F. doi:10.3847/1538-4365/aae1a3. S2CID 119368148. 16.
  6. ^ Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: 8. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408. A7.
  7. ^ a b c 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.
  8. ^ a b c d Andrade, Manuel (October 2019). "Colour-dependent accurate modelling of dynamical parallaxes and masses of visual binaries. Application to the VB+SB2 systems with definitive orbits". Astronomy & Astrophysics. 630: 11. Bibcode:2019A&A...630A..96A. doi:10.1051/0004-6361/201936199. S2CID 202933213. A96.
  9. ^ a b c d e f g 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.
  10. ^ a b c 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.
  11. ^ a b "HD 178911". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-13.
  12. ^ "HD 178911B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-13.
  13. ^ a b Zucker, S.; et al. (2002). "A Planet Candidate in the Stellar Triple System HD 178911". The Astrophysical Journal. 568 (1): 363–368. arXiv:astro-ph/0111550. Bibcode:2002ApJ...568..363Z. doi:10.1086/338892. S2CID 16548934.
  14. ^ McAlister, H. A.; et al. (1987). "ICCD speckle observations of binary stars. I - A survey for duplicity among the bright stars". The Astronomical Journal. 93: 183–194. Bibcode:1987AJ.....93..183M. doi:10.1086/114297.
  15. ^ "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 29, 2012.
  16. ^ Butler, R. P.; et al. (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.