Zeta Sagittae

Zeta Sagittae
Location of ζ Sagittae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagitta
Right ascension 19h 48m 58.65978s[1]
Declination +19° 08′ 31.3516″[1]
Apparent magnitude (V) +5.00[2] (5.64 + 6.04 + 9.01)[3]
Characteristics
Spectral type A3 Vnn[4] (A1 V + A3 V)[5]
U−B color index +0.06[2]
B−V color index +0.10[2]
Astrometry
Proper motion (μ) RA: +17.63[1] mas/yr
Dec.: +26.27[1] mas/yr
Parallax (π)12.79 ± 0.67 mas[1]
Distance260 ± 10 ly
(78 ± 4 pc)
Absolute magnitude (MV)+0.55[6]
Orbit[7]
Period (P)8487.9±4.9 d
Semi-major axis (a)0.13605±0.00044″
Eccentricity (e)0.7948±0.0019
Inclination (i)132.33±0.41°
Longitude of the node (Ω)340.97±0.68°
Periastron epoch (T)44199.6±5.9 HMJD
Argument of periastron (ω)
(secondary)		355.3±1.0°
Details
ζ Sge A
Mass1.80[8] M☉
Radius1.7[9] R☉
Luminosity46[10] L☉
Surface gravity (log g)3.89[8] cgs
Temperature8,422±286[8] K
Rotational velocity (v sin i)240[11] km/s
Age347[8] Myr
Other designations
ζ Sge, 8 Sge, BD+19°4229, GC 27431, HD 187362, HIP 97496, HR 7546, SAO 105298, PPM 137034, ADS 12973, WDS J19490+1909AB[12]
Database references
SIMBADdata

Zeta Sagittae (ζ Sagittae) is triple star[3] system in the northern constellation of Sagitta. It is visible to the naked eye, having a combined apparent visual magnitude of +5.00.[2] Based upon an annual parallax shift of 12.79 mas,[1] the distance to this star is approximately 260 light years.

The inner pair is a visual binary system consisting of two A-type main-sequence stars with an orbital period of 23.2 years (8,487.9 d), a semimajor axis of 0.136 arc seconds, and an eccentricity of 0.79.[7] The primary, component A, has a visual magnitude of 5.64[3] with a stellar classification of A3 Vnn,[4] where the 'nn' suffix indicates "nebulous" lines due to rotation. It is spinning rapidly with a projected rotational velocity of 240 km/s. This is giving the star an oblate shape with an equatorial bulge that is 14% larger than the polar radius.[11]

The secondary member, component B, is a magnitude 6.04 star, while the more distant component C is magnitude 9.01 and lies at an angular separation of 8.330 arc seconds from the other two.[3]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Christy1969 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Muterspaugh2010 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference David2015 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference PasinettiFracassini2001 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference belle2012 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).