HD 128311

HD 128311

A near infrared (Y band) light curve for HN Boötes, adapted from Strassmeier et al. (2000)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 36m 00.56073s[2]
Declination +09° 44′ 47.4536″[2]
Apparent magnitude (V) 7.48[3]
Characteristics
Spectral type K3V[4]
B−V color index 0.973±0.004[3]
Variable type BY Dra[5]
Astrometry
Radial velocity (Rv)−9.62±0.15[2] km/s
Proper motion (μ) RA: 204.360[2] mas/yr
Dec.: −250.390[2] mas/yr
Parallax (π)61.2111 ± 0.0740 mas[2]
Distance53.28 ± 0.06 ly
(16.34 ± 0.02 pc)
Absolute magnitude (MV)6.39[3]
Details[6]
Mass0.82 M☉
Radius0.78±0.01[2] R☉
Luminosity0.308±0.001[2] L☉
Surface gravity (log g)4.58 cgs
Temperature4,863+46
−15[2] K
Metallicity [Fe/H]0.08[7] dex
0.12[6] dex
Rotational velocity (v sin i)5.6 km/s
Age0.5–1.0 Gyr[8]
6.35[6] Gyr
Other designations
HN Boo, BD+10° 2710, GC 19679, GJ 3860, HD 128311, HIP 71395, SAO 120554, LTT 14312, GSC 00910-00165[9]
Database references
SIMBADdata
ARICNSdata

HD 128311 is a variable star in the northern constellation of Boötes. It has the variable star designation HN Boötis, while HD 128311 is the star's designation in the Henry Draper Catalogue. The star is invisible to the naked eye with an apparent visual magnitude that fluctuates around 7.48.[3] It is located at a distance of 53 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −9.6 km/s.[2] Two confirmed extrasolar planets have been detected in orbit around this star.[8]

The stellar classification of HN Boo is K3V,[4] which indicates this is a K-type main sequence star. It is a BY Draconis-type variable, randomly varying in brightness by 0.04 in magnitude over a period of 11.54 days[5] due to star spots and high chromospheric activity. The star exhibits strong emission, which suggests an age of 0.5–1.0 billion years.[8] It has 82% of the mass of the Sun and 78% of the Sun's radius. The metallicity of the star, meaning its abundance of heavier elements, appears slightly higher than in the Sun. It is radiating 31% of the luminosity of the Sun from its photosphere at an effective temperature of 4,863 K.[6]

  1. ^ Cite error: The named reference Strassmeier was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Koen_et_al_2010 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Luck2017 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Rein2009 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Vogt2005 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).