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]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Mason_et_al_2014 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Farrington2014 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference France_et_al_2018 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Soubiran_et_al_2018 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference GaiaDR2B was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Andrade2019 was invoked but never defined (see the help page).
  9. ^ a b c d e f Cite error: The named reference Bonfanti_et_al_2016 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Luck2017 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD_B was invoked but never defined (see the help page).