HD 173416

HD 173416 / Xihe
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra[1]
Right ascension 18h 43m 36.109s[2]
Declination +36° 33′ 23.78″[2]
Apparent magnitude (V) 6.04[1]
Characteristics
Evolutionary stage Giant[3]
Spectral type G8 III[4]
Apparent magnitude (B) 7.080[1]
Apparent magnitude (J) 4.580±0.264[1]
Apparent magnitude (H) 3.929±0.232[1]
Apparent magnitude (K) 3.814±0.354[1]
B−V color index 1.040±0.006[1]
Astrometry
Radial velocity (Rv)−61.17±0.29[5] km/s
Proper motion (μ) RA: 20.946 mas/yr[2]
Dec.: 58.198 mas/yr[2]
Parallax (π)7.5363 ± 0.0238 mas[2]
Distance433 ± 1 ly
(132.7 ± 0.4 pc)
Absolute magnitude (MV)0.406[3]
Details
Mass1.8±0.2[6] M☉
Radius13.0±0.3[6] R☉
Luminosity79±2[6] L☉
Surface gravity (log g)2.5±0.1[6] cgs
Temperature4,790±37[6] K
Metallicity [Fe/H]−0.22±0.09[3] dex
Rotation323.6 d[4]
Rotational velocity (v sin i)2.7[4] km/s
Age1.8±0.7[6] Gyr
Other designations
AG+36 1680, BD+36 3246, GC 25640, HD 173416, HIP 91852, HR 7043, SAO 67292, PPM 81707, TYC 2649-1153-1, GCRV 11177, GSC 02649-01153, IRAS 18418+3630, 2MASS J18433610+3633237[7]
Database references
SIMBADdata
Exoplanet Archivedata

HD 173416, also named Xihe, is a star with an orbiting exoplanet in the northern constellation of Lyra. It is located at a distance of approximately 433 light years based on parallax measurements,[2] but is drifting closer to the Sun with a radial velocity of −61 km/s.[5] It has a bright absolute magnitude of 0.406,[3] but a much fainter apparent visual magnitude of 6.04.[1] This indicates the star is dimly visible to the naked eye.

The spectrum of HD 173416 indicates this is an evolved G-type giant star with a stellar classification of G8 III.[4] This means it has consumed the hydrogen at its stellar core and evolved off the main sequence. At an age of around two billion years, it has expanded to 13 times the radius of the Sun. The star has 1.8 times the mass of the Sun and is radiating 79 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,790 K.[6] Based on the abundance of iron in the stellar atmosphere, it has a sub-solar metallicity.[3]

The star HD 173416 is named Xihe (羲和). The name was selected in the NameExoWorlds campaign by Nanjing, during the 100th anniversary of the IAU. Xihe is the goddess of the sun in the Chinese mythology and also represents the earliest astronomers and developers of calendars in ancient China. The exoplanet is named Wangshu (望舒) after the goddess who drives the Moon across the sky in Chinese mythology.[8][9]

  1. ^ a b c d e f g h Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Liu was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Döllinger_Hartmann_2021 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Soubiran_et_al_2018 was invoked but never defined (see the help page).
  6. ^ a b c d e f g Cite error: The named reference Bonfanti_et_al_2016 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference exoworlds was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference IAU was invoked but never defined (see the help page).