Zeta Sagittarii information

ζ Sagittarii
	Location of ζ Sagittarii (circled)
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Sagittarius
Right ascension	19h 02m 36.73024s
Declination	–29° 52′ 48.2279″
Apparent magnitude (V)	+2.59 (3.27/3.48)
Characteristics
Spectral type	A2.5 Va
U−B color index	+0.05
B−V color index	+0.08
Astrometry
Radial velocity (Rv)	+22 km/s
Proper motion (μ)	RA: +10.79 mas/yr ; Dec.: +21.11 mas/yr
Parallax (π)	36.98 ± 0.87 mas
Distance	88 ± 2 ly ; (27.0 ± 0.6 pc)
Absolute magnitude (MV)	1.11/1.32
Orbit
Period (P)	21.00 ± 0.01 years
Semi-major axis (a)	0.489 ± 0.001″
Eccentricity (e)	0.211 ± 0.001
Inclination (i)	111.1 ± 0.1°
Longitude of the node (Ω)	74.0 ± 0.1°
Periastron epoch (T)	2005.99 ± 0.03
Argument of periastron (ω); (secondary)	7.2 ± 0.6°
Details
Mass	5.26 ± 0.37 M☉
Surface gravity (log g)	3.90 cgs
Temperature	8,799 K
Rotational velocity (v sin i)	77 km/s
Age	500–710 Myr
Other designations
	Ascella, ζ Sagittarii, ζ Sgr, Zeta Sgr, 38 Sagittarii, CCDM J19026-2953AB, CPD-30 5798, GC 26161, HD 176687, HIP 93506, HR 7194, IDS 18562-3001 AB, PPM 269230, SAO 187600, WDS J19026-2953AB
Database references
SIMBAD	data

Zeta Sagittarii (ζ Sagittarii, abbreviated Zeta Sgr, ζ Sgr) is a triple star system and the third-brightest star in the constellation of Sagittarius after Kaus Australis and Nunki. Based upon parallax measurements, it is about 88 light-years (27 parsecs) from the Sun.^[1]

The three components are designated Zeta Sagittarii A (officially named Ascella /əˈsɛlə/, the traditional name for the entire system)^[8]^[9] and B, themselves forming a binary pair, and a smaller companion star, C.

^ ^a ^b ^c ^d ^e ^f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference clpl4 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e Cite error: The named reference de_rosa_et_al_2011 was invoked but never defined (see the help page).
^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^ Cite error: The named reference gcsrv was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aj126_4_2048 was invoked but never defined (see the help page).
^ Cite error: The named reference aaa463_2_671 was invoked but never defined (see the help page).
^ Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 8–30. Bibcode:1944PA.....52....8D.
^ "Naming Stars". IAU.org. Retrieved 16 December 2017.

[aaa474_2_653-1] ^ ^a ^b ^c ^d ^e ^f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).

[clpl4-2] Cite error: The named reference clpl4 was invoked but never defined (see the help page).

[de_rosa_et_al_2011-3] Cite error: The named reference de_rosa_et_al_2011 was invoked but never defined (see the help page).

[SIMBAD-4] Cite error: The named reference SIMBAD was invoked but never defined (see the help page).

[gcsrv-5] Cite error: The named reference gcsrv was invoked but never defined (see the help page).

[aj126_4_2048-6] Cite error: The named reference aj126_4_2048 was invoked but never defined (see the help page).

[aaa463_2_671-7] Cite error: The named reference aaa463_2_671 was invoked but never defined (see the help page).

[Davis44-8] Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 8–30. Bibcode:1944PA.....52....8D.

[IAU-LSN-9] "Naming Stars". IAU.org. Retrieved 16 December 2017.

Observation data Epoch J2000.0 Equinox J2000.0
Location of ζ Sagittarii (circled)
Constellation	Sagittarius
Right ascension	19^h 02^m 36.73024^s^[1]
Declination	–29° 52′ 48.2279″^[1]
Apparent magnitude (V)	+2.59^[2] (3.27/3.48)^[3]
Characteristics
Spectral type	A2.5 Va^[4]
U−B color index	+0.05^[2]
B−V color index	+0.08^[2]
Astrometry

Radial velocity (R_v)	+22^[5] km/s
Proper motion (μ)	RA: +10.79^[1] mas/yr Dec.: +21.11^[1] mas/yr
Parallax (π)	36.98 ± 0.87 mas^[1]
Distance	88 ± 2 ly (27.0 ± 0.6 pc)
Absolute magnitude (M_V)	1.11/1.32^[3]

Orbit^[3]
Period (P)	21.00 ± 0.01 years
Semi-major axis (a)	0.489 ± 0.001″
Eccentricity (e)	0.211 ± 0.001
Inclination (i)	111.1 ± 0.1°
Longitude of the node (Ω)	74.0 ± 0.1°
Periastron epoch (T)	2005.99 ± 0.03
Argument of periastron (ω) (secondary)	7.2 ± 0.6°
Details

Mass	5.26 ± 0.37^[3] `M`_☉
Surface gravity (log g)	3.90^[6] cgs
Temperature	8,799^[6] K
Rotational velocity (v sin i)	77^[7] km/s
Age	500–710^[3] Myr

Other designations
Ascella, ζ Sagittarii, ζ Sgr, Zeta Sgr, 38 Sagittarii, CCDM J19026-2953AB, CPD-30 5798, GC 26161, HD 176687, HIP 93506, HR 7194, IDS 18562-3001 AB, PPM 269230, SAO 187600, WDS J19026-2953AB
Database references
SIMBAD	data

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