Lambda Hydrae

λ Hydrae, Latinised as Lambda Hydrae, is a spectroscopic binary^[14] star in the constellation Hydra. Its apparent magnitude is 3.61 Located around 33.3 parsecs (109 ly) distant. The spiral galaxy NGC 3145 is only 7.8′ away to the southwest.

λ Hydrae

Location of λ Hydrae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Hydra
Right ascension	10h 10m 35.27667s[1]
Declination	−12° 21′ 14.6938″[1]
Apparent magnitude (V)	3.61[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	K0IIIbCN0.5[4]
U−B color index	+0.92[5]
B−V color index	+1.00[5]
Astrometry
Radial velocity (Rv)	19.4[6] km/s
Proper motion (μ)	RA: −201.27[1] mas/yr Dec.: −99.63[1] mas/yr
Parallax (π)	30.0232±0.6973 mas[7]
Distance	109 ± 3 ly (33.3 ± 0.8 pc)
Absolute magnitude (MV)	+0.92[8]
Orbit[9]
Period (P)	1585.8 days
Semi-major axis (a)	16.79 mas
Eccentricity (e)	0.138
Inclination (i)	79.49°
Longitude of the node (Ω)	249.62°
Periastron epoch (T)	2448664.3906
Argument of periastron (ω) (secondary)	238.9°
Details
λ Hya A
Mass	1-2[10] M☉
Radius	8.62+0.22 −0.23[11] R☉
Luminosity	39.8[10] L☉
Surface gravity (log g)	2.64[10] cgs
Temperature	4,656[10] K
Metallicity [Fe/H]	+0.25[12] dex
Rotational velocity (v sin i)	1.9[13] km/s
Other designations
λ Hya, 41 Hydrae, BD−11°2820, HD 88284, HIP 49841, SAO 155785, HR 3994, GC 13982, TYC 5485-1310-1
Database references
SIMBAD	data

The primary is an orange giant of spectral type K0IIICN+1,^[15] a star that has used up its core hydrogen, left the main sequence, and expanded into a giant. It is considered to be a red clump giant, a cool horizontal branch star that is burning helium in its core.^[3]

λ Hydrae has two visual companions, components B and C, 11th and 13th magnitude stars respectively 71″ and 111″ away.^[16]