Zeta² Scorpii

ζ² Scorpii

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Scorpius
Right ascension	16h 54m 35.0053s[1]
Declination	−42° 21′ 40.726″[1]
Apparent magnitude (V)	3.59 to 3.65[2]
Characteristics
Spectral type	K4III[1]
U−B color index	+1.65[3]
B−V color index	+1.37[3]
R−I color index	+0.68[3]
Astrometry
Radial velocity (Rv)	−18.7 ± 0.9[1] km/s
Proper motion (μ)	RA: −126.55[1] mas/yr Dec.: −227.77[1] mas/yr
Parallax (π)	21.67 ± 0.85[1] mas
Distance	151 ± 6 ly (46 ± 2 pc)
Absolute magnitude (MV)	0.3[4]
Details
Mass	1.8 - 2[citation needed] M☉
Radius	48[5] R☉
Other designations
ζ2 Sco, Zeta2 Scorpii, Zeta2 Sco, CD−42 11646, CPD−42 7549, GC 22751, HD 152334, HIP 82729, HR 6271, LTT 6737, NLTT 43744, PPM 322371, SAO 227402.[1]
Database references
SIMBAD	data

For other stars with this Bayer designation, see Zeta Scorpii.

Zeta² Scorpii (Zeta² Sco, ζ² Scorpii, ζ² Sco) is a K-type orange giant star in the constellation of Scorpius.^[1] It has an apparent visual magnitude which varies between 3.59 and 3.65,^[2] and is located near the blue-white supergiant star Zeta-1 Scorpii in our sky, although it is, in astronomical terms, far more distant and unrelated to Zeta-1 Scorpii except for line-of sight co-incidence. Zeta-1 is five thousand seven hundred light-years away and probably an outlying member of open star cluster NGC 6231, also known as the "northern jewel box" cluster, whereas Zeta-2 is a mere 155 lightyears distant and thus much less luminous in real terms. Zeta-2 Scorpii can also be distinguished from its optical partner, Zeta-1, because of Zeta-2's orangish colour especially in long-exposure astrophographs.

References

1. ^ ^{a b c d e f g h i} NSV 8028 -- Variable Star, database entry, SIMBAD. Accessed on line November 20, 2009.
2. ^ ^{a b} NSV 8028, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 20, 2009.
3. ^ ^{a b c} HR 6271, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 20, 2009.
4. ^ From apparent magnitude and parallax.
5. ^ HD 152334, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line November 20, 2009.