Delta2 Gruis

Delta² Gruis, Latinized from δ² Gruis, is a solitary,^[11] red-hued star in the southern constellation of Grus. It is visible to the naked eye with an apparent visual magnitude of about 4. Based upon an annual parallax shift of 9.88 mas as seen from the Earth, the star is located around 330 light years from the Sun. It is moving further away from the Sun with a radial velocity of +3 km/s.^[6]

For other stars with this Bayer designation, see δ Gruis.

Delta² Gruis

A light curve for Delta2 Gruis, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Grus
Right ascension	22h 29m 45.43402s[2]
Declination	−43° 44′ 57.1968″[2]
Apparent magnitude (V)	3.99 - 4.20[3]
Characteristics
Spectral type	M4.5 IIIa[4]
U−B color index	+1.71[5]
B−V color index	+1.57[5]
Variable type	LB?[3]
Astrometry
Radial velocity (Rv)	+2.7±0.8[6] km/s
Proper motion (μ)	RA: −14.08[2] mas/yr Dec.: +2.57[2] mas/yr
Parallax (π)	9.1556±0.1885 mas[7]
Distance	356 ± 7 ly (109 ± 2 pc)
Absolute magnitude (MV)	−0.90±0.05[4]
Details
Radius	97[8] R☉
Luminosity	1,359[8] L☉
Surface gravity (log g)	+0.45[8] cgs
Temperature	3,560[8] K
Rotational velocity (v sin i)	+4.5±0.8[9] km/s
Other designations
δ2 Gru, CD−44°14935, HD 213080, HIP 111043, HR 8560, SAO 231161, WDS J22298-4345A[10]
Database references
SIMBAD	data

This is an evolved red giant star with a stellar classification of M4.5 IIIa.^[4] It is a pulsating variable with multiple periods, including 20.6, 24.1, 24.5, and 32.3 days. The strongest period is 33.3 days with an amplitude of 0.043 magnitude.^[12] It has a magnitude 9.71 visual companion at an angular separation of 60.4 arc seconds along a position angle of 210°, as of 2013.^[13]