26 Hydrae

26 Hydrae
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 09h 19m 46.38309s[1]
Declination −11° 58′ 29.4577″[1]
Apparent magnitude (V) 4.770[2] + 12.4[3]
Characteristics
Spectral type G7III[4] or G8II[5]
U−B color index +0.67[6]
B−V color index +0.927±0.017[7]
Astrometry
Radial velocity (Rv)−1.18±0.09[8] km/s
Proper motion (μ) RA: −29.269[1] mas/yr
Dec.: +11.613[1] mas/yr
Parallax (π)9.7770 ± 0.1610 mas[1]
Distance334 ± 5 ly
(102 ± 2 pc)
Absolute magnitude (MV)−0.29[7]
Details
26 Hya A
Mass2.72[9] M☉
Radius15.14+0.81
−2.47[1] R☉
Luminosity138.5±2.7[1] L☉
Surface gravity (log g)2.48±0.07[10] cgs
Temperature5,003±82[9] K
Metallicity [Fe/H]−0.13±0.06[10] dex
Rotational velocity (v sin i)2.7[8] km/s
Age0.51[9] Gyr
Other designations
26 Hya, BD−11°2609, FK5 2741, HD 80499, HIP 45751, HR 3706, SAO 155096, WDS J09198-1158AB[11]
Database references
SIMBADdata

26 Hydrae is a binary star[3] system located 334 light years away from the Sun in the equatorial constellation of Hydra. It is visible to the naked eye as a faint, yellow-hued point of light with a combined apparent visual magnitude of 4.77,[2] just a few degrees away from Alphard. The system is moving closer to the Earth with a leisurely radial velocity of -1 km/s.[8]

Keenan and McNeil (1989) gave the brighter component a stellar classification of G7 III,[4] matching an aging giant star. Houk and Swift (1999) have it classed as a G8II[5] bright giant. This is a red clump giant,[12] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. It has a high lithium abundance and displays a far infrared emission excess.[13] The star is an estimated 510[9] million years old with 2.72[9] times the mass of the Sun and has expanded to 15[1] times the Sun's radius. It is radiating 139[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,003 K.[9]

The secondary component is a magnitude 12.4 star at an angular separation of 3.2″, as of 2008.[3]

  1. ^ a b c d e f g h i Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference TYC2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Keenan1989 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference HD was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference EgUBV was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Massarotti was invoked but never defined (see the help page).
  9. ^ a b c d e f Cite error: The named reference Luck was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Wu was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Alves2000 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Jasniewiczw2000 was invoked but never defined (see the help page).