26 Hydrae

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.^[9]

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
Evolutionary stage	red clump[4]
Spectral type	G7III[5] or G8II[6]
U−B color index	+0.67[7]
B−V color index	+0.927±0.017[8]
Astrometry
Radial velocity (Rv)	−1.18±0.09[9] 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]
Distance	334 ± 5 ly (102 ± 2 pc)
Absolute magnitude (MV)	−0.29[8]
Details
26 Hya A
Mass	2.72[10] M☉
Radius	15.14+0.81 −2.47[1] R☉
Luminosity	138.5±2.7[1] L☉
Surface gravity (log g)	2.48±0.07[11] cgs
Temperature	5,003±82[10] K
Metallicity [Fe/H]	−0.13±0.06[11] dex
Rotational velocity (v sin i)	2.7[9] km/s
Age	0.51[10] Gyr
Other designations
26 Hya, BD−11°2609, FK5 2741, HD 80499, HIP 45751, HR 3706, SAO 155096, WDS J09198-1158AB[12]
Database references
SIMBAD	data

Keenan and McNeil (1989) gave the brighter component a stellar classification of G7 III,^[5] matching an aging giant star. Houk and Swift (1999) have it classed as a G8II^[6] bright giant. This is a red clump giant,^[4] 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^[10] million years old with 2.72^[10] 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.^[10]

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