Nu Tucanae

ν Tucanae, Latinized as Nu Tucanae, is a solitary,^[11] variable star in the southern constellation of Tucana. This red-hued object is visible to the naked eye as a faint star with an apparent visual magnitude that fluctuates around +4.80.^[5] It is located approximately 290 light years from the Sun based on parallax,^[2] but is drifting closer with a radial velocity of −3 km/s.^[7]

Nu Tucanae

A light curve for Nu Tucanae, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Tucana
Right ascension	22h 33m 00.06240s[2]
Declination	−61° 58′ 55.6390″[2]
Apparent magnitude (V)	4.75 - 4.93[3]
Characteristics
Spectral type	M4 III[4]
U−B color index	+1.73[5]
B−V color index	+1.61[5]
Variable type	Lb:[6]
Astrometry
Radial velocity (Rv)	−3.4±0.8[7] km/s
Proper motion (μ)	RA: −3.40[2] mas/yr Dec.: −0.8[2] mas/yr
Parallax (π)	11.24±0.23 mas[2]
Distance	290 ± 6 ly (89 ± 2 pc)
Absolute magnitude (MV)	+0.16[8]
Details
Radius	64.37[9] R☉
Luminosity	554±41[9] L☉
Surface gravity (log g)	0.778[9] cgs
Temperature	3472±125[9] K
Other designations
ν Tuc, CPD−62°6348, FK5 3803, HD 213442, HIP 111310, HR 8582, SAO 255247[10]
Database references
SIMBAD	data

This object is an aging red giant with a stellar classification of M4 III,^[4] currently on the asymptotic giant branch.^[6] With the supply of hydrogen exhausted at its core, the star has cooled and expanded off the main sequence; at present it has 49 times the Sun's radius.^[12] It is classified as a slow irregular variable and its brightness varies from magnitude +4.75 to +4.93.^[3] Cyclical periods of 22.3, 24.4, 24.8, 25.1, 25.5, 33.8, 50.6, 80.1, 123.2, and 261.8 days have been reported for its variations.^[13] On average, the star is radiating around 400^[12] times the luminosity of the Sun from its photosphere at an effective temperature of 3,674 K.^[12]