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Star in the constellation Ophiuchus
σ Ophiuchi
Location of σ Ophiuchi (circled)
Observation data
Epoch J2000
Equinox J2000
Constellation
Ophiuchus
Right ascension
17h 26m 30.8806s
[1]
Declination
4° 08′ 25.2876″
[1]
Apparent magnitude (V)
4.31
[2] (4.25 - 4.51
[3] )
Characteristics
Spectral type
K2 III
[4]
U−B
color index
+1.57
[2]
B−V
color index
+1.51
[2]
Variable type
suspected
[3]
Astrometry
Radial velocity (Rv ) -27.81
[5] km/s
Proper motion (μ)
RA: +1.459
[6]
mas /
yr
Dec.: +6.760
[6]
mas /
yr
Parallax (π) 3.7578 ± 0.1559
mas
[6]
Distance 870 ± 40
ly (270 ± 10
pc )
Absolute magnitude (MV ) -2.85
[7]
Details
Mass 4.87
[8]
M ☉
Radius 94
[9]
R ☉
Luminosity 1,995 - 2,032
[9]
L ☉
Surface gravity (log g ) 1.52
[10]
cgs
Temperature 3,986± 170
[9]
K
Metallicity [Fe/H]-0.07
[8]
dex
Rotational velocity (v sin i ) 4.2
[11] km/s
Other designations
σ Oph ,
49 Ophiuchi ,
NSV 8664,
BD +04° 3422 ,
FK5 1459,
GC 23621,
HD 157999,
HIP 85355,
HR 6498,
SAO 122387,
2MASS J17263087+0408252
Database references
SIMBAD
data
Sigma Ophiuchi ,
Latinized from σ Ophiuchi, is a single,
[12] orange-hued
star in the equatorial
constellation
Ophiuchus . Its
apparent visual magnitude is 4.31,
[2] which is bright enough to be faintly visible to the naked eye. The annual
parallax shift of 3.62
mas as seen from Earth provides a distance estimate of roughly 900
light years . It is moving closer to the Sun with a
radial velocity of −28 km/s.
[5]
This is an
evolved
giant star of
type K with a
stellar classification of K2 III.
[4] Wittkowski et al. (2017) consider it to have a
luminosity class of II-III, suggesting it is in a transitional zone between giants and
supergiant stars .
[13] It has around 5 times the
mass of the Sun and 73 times the
Sun's radius . The star is radiating 2,047 times the
Sun's luminosity from its enlarged
photosphere at an
effective temperature of 4,540 K.
[8]
References
^
a
b
Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018).
"Gaia Data Release 2: Summary of the contents and survey properties" .
Astronomy & Astrophysics . 616 . A1.
arXiv :
1804.09365 .
Bibcode :
2018A&A...616A...1G .
doi :
10.1051/0004-6361/201833051 .
Gaia DR2 record for this source at
VizieR .
^
a
b
c
d Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues . 2237 .
Bibcode :
2002yCat.2237....0D .
^
a
b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S . 1 .
Bibcode :
2009yCat....102025S .
^
a
b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey . 05 : 0.
Bibcode :
1999MSS...C05....0H .
^
a
b Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy & Astrophysics . 430 : 165–186.
arXiv :
astro-ph/0409579 .
Bibcode :
2005A&A...430..165F .
doi :
10.1051/0004-6361:20041272 .
S2CID
17804304 .
^
a
b
c
Brown, A. G. A. ; et al. (Gaia collaboration) (2021).
"Gaia Early Data Release 3: Summary of the contents and survey properties" .
Astronomy & Astrophysics . 649 : A1.
arXiv :
2012.01533 .
Bibcode :
2021A&A...649A...1G .
doi :
10.1051/0004-6361/202039657 .
S2CID
227254300 . (Erratum:
doi :
10.1051/0004-6361/202039657e ) .
Gaia EDR3 record for this source at
VizieR .
^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331.
arXiv :
1108.4971 .
Bibcode :
2012AstL...38..331A .
doi :
10.1134/S1063773712050015 .
S2CID
119257644 .
Vizier catalog entry
^
a
b
c Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas (2015). "Precise radial velocities of giant stars". Astronomy & Astrophysics . 574 : A116.
arXiv :
1412.4634 .
Bibcode :
2015A&A...574A.116R .
doi :
10.1051/0004-6361/201322360 .
hdl :
10722/215277 .
S2CID
59334290 .
Vizier catalog entry
^
a
b
c Messineo, M.; Brown, A. G. A. (2019).
"A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2" . The Astronomical Journal . 158 (1): 20.
arXiv :
1905.03744 .
Bibcode :
2019AJ....158...20M .
doi :
10.3847/1538-3881/ab1cbd .
S2CID
148571616 .
^ Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars". Astronomy and Astrophysics . 475 (3): 1003.
arXiv :
0709.1145 .
Bibcode :
2007A&A...475.1003H .
doi :
10.1051/0004-6361:20078233 .
S2CID
10436552 .
^ De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series . 139 (3): 433.
arXiv :
astro-ph/0608248 .
Bibcode :
1999A&AS..139..433D .
doi :
10.1051/aas:1999401 .
Vizier catalog entry
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems",
Monthly Notices of the Royal Astronomical Society , 389 (2): 869–879,
arXiv :
0806.2878 ,
Bibcode :
2008MNRAS.389..869E ,
doi :
10.1111/j.1365-2966.2008.13596.x ,
S2CID
14878976 .
^ Wittkowski, M.; et al. (January 2017), "VLTI/AMBER spectro-interferometry of the late-type supergiants V766 Cen (=HR 5171 A), σ Oph, BM Sco, and HD 206859", Astronomy & Astrophysics , 597 : 16,
arXiv :
1610.01927 ,
Bibcode :
2017A&A...597A...9W ,
doi :
10.1051/0004-6361/201629349 ,
S2CID
55679854 , A9.