Sigma Sagittarii information

Sigma Sagittarii
	Location of σ Sagittarii (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Sagittarius
Right ascension	18h 55m 15.92650s
Declination	–26° 17′ 48.2068″
Apparent magnitude (V)	2.05
Characteristics
Spectral type	B2.5 V
U−B color index	–0.761
B−V color index	–0.204
Astrometry
Radial velocity (Rv)	–11.2 km/s
Proper motion (μ)	RA: +15.14 mas/yr ; Dec.: –53.43 mas/yr
Parallax (π)	14.32 ± 0.29 mas
Distance	228 ± 5 ly ; (70 ± 1 pc)
Absolute magnitude (MV)	−2.17
Details
Mass	7.8±0.2 M☉
Radius	4.5 R☉
Luminosity	3,300 L☉
Temperature	18,890 K
Rotational velocity (v sin i)	165 km/s
Age	31.4±0.4 Myr
Other designations
	Nunki, Sadira, σ Sgr, Sigma Sgr, 34 Sagittarii, CPD−27 5241, FK5 706, GC 25941, HD 175191, HIP 92855, HR 7121, SAO 187448, PPM 269078, CCDM J18552-2618A, WDS J18553-2618Aa,Ab
Database references
SIMBAD	data

Sigma Sagittarii, Latinized from σ Sagittarii; formally named Nunki /ˈnʌŋki/,^[13]^[14] is the second-brightest star in the constellation of Sagittarius. It has an apparent magnitude of +2.05,^[3] making it readily visible to the naked eye. The distance to this star, determined using parallax measurements from the Hipparcos astrometry satellite,^[15] yields a value of approximately 228 light-years (70 parsecs) from the Sun.^[1]^[2]

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^ Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 26. Bibcode:1944PA.....52....8D.
^ "Naming Stars". IAU.org. Retrieved 16 December 2017.
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[Davis44-13] Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 26. Bibcode:1944PA.....52....8D.

[IAU-LSN-14] "Naming Stars". IAU.org. Retrieved 16 December 2017.

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Observation data Epoch J2000 Equinox J2000
Location of σ Sagittarii (circled)
Constellation	Sagittarius
Right ascension	18^h 55^m 15.92650^s^[1]^[2]
Declination	–26° 17′ 48.2068″^[1]^[2]
Apparent magnitude (V)	2.05^[3]
Characteristics
Spectral type	B2.5 V^[4]
U−B color index	–0.761^[5]
B−V color index	–0.204^[5]
Astrometry

Radial velocity (R_v)	–11.2^[3] km/s
Proper motion (μ)	RA: +15.14^[1]^[2] mas/yr Dec.: –53.43^[1]^[2] mas/yr
Parallax (π)	14.32 ± 0.29 mas^[1]^[2]
Distance	228 ± 5 ly (70 ± 1 pc)
Absolute magnitude (M_V)	−2.17^[6]

Details

Mass	7.8±0.2^[7] `M`_☉
Radius	4.5^[8] `R`_☉
Luminosity	3,300^[9] `L`_☉
Temperature	18,890^[9] K
Rotational velocity (v sin i)	165^[10] km/s
Age	31.4±0.4^[7] Myr

Other designations
Nunki, Sadira^[11]^[12], σ Sgr, Sigma Sgr, 34 Sagittarii, CPD−27 5241, FK5 706, GC 25941, HD 175191, HIP 92855, HR 7121, SAO 187448, PPM 269078, CCDM J18552-2618A, WDS J18553-2618Aa,Ab
Database references
SIMBAD	data

Sigma Sagittarii information

and 22 Related for: Sigma Sagittarii information

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Astronomical naming conventions

Pi Sagittarii

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HR 7703

Eddington luminosity

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Former constellations

List of Arabic star names

List of nearest stars and brown dwarfs

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List of nearest bright stars

Telescopium