Delta Sagittae
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Sagitta |
| Right ascension | 19h 47m 23.26653s[1] |
| Declination | +18° 32′ 03.5203″[1] |
| Apparent magnitude (V) | +3.82[2](3.91[3]/ 6.64)[4] |
| Characteristics | |
| Evolutionary stage | AGB + main sequence[5] |
| Spectral type | M2II + B9.5V[4] |
| U−B color index | +0.98[6] |
| B−V color index | +1.40[6] |
| Variable type | LB?[7] |
| Astrometry | |
| Radial velocity (Rv) | 2.5 ± 0.9[8] km/s |
| Proper motion (μ) | RA: -6.514[1] mas/yr Dec.: 0.849[1] mas/yr |
| Parallax (π) | 5.9674±0.2597 mas[9] |
| Distance | 550 ± 20 ly (168 ± 7 pc) |
| Absolute magnitude (MV) | −2.58[10] |
| Orbit[11] | |
| Period (P) | 3,703.7±1.5 days |
| Semi-major axis (a) | (5.50±0.04)×108 km[a] |
| Eccentricity (e) | 0.441±0.005 |
| Inclination (i) | 40° |
| Longitude of the node (Ω) | 170.2[4]° |
| Periastron epoch (T) | 1979.93[4] |
| Argument of periastron (ω) (secondary) | 263.9±1.0° |
| Details | |
| δ Sge A | |
| Mass | 3.8[11] M☉ |
| Radius | 180±25[11] R☉ |
| Luminosity | 3,162[4] L☉ |
| Surface gravity (log g) | 0.74±0.10[5] cgs |
| Temperature | 3,660±170[12] K |
| δ Sge B | |
| Mass | 3.611[13] M☉ |
| Radius | 3.3 – 4.7[13] R☉ |
| Luminosity | 63[4] L☉ |
| Temperature | 10,000[4] K |
| Other designations | |
| Zuoqi, δ Sge, 7 Sge, BD+18 4240, FK5 743, GC 27391, HD 187076, HIP 97365, HR 7536, SAO 105259, PPM 136976, CCDM J19474+1832AB, WDS J19474+1832AB, IDS 19429+1817 AB[2] | |
| Database references | |
| SIMBAD | data |
Delta Sagittae, also named Zuoqi,[14] is a binary star in the constellation of Sagitta, with an apparent magnitude of +3.68. The primary component is a red M-type bright giant, and the secondary is a B-type main-sequence star.[2] It is approximately 430 light years from Earth, based on its Gaia Data Release 2 parallax.[1]
Delta Sagittae is a spectroscopic binary with a composite spectrum, meaning that light from both stars can be detected. It has an orbital period of about 10 years and an eccentricity of about 0.44.[4] It is also a variable star, with its brightness changing between a maximum of magnitude 3.75 and a minimum of 3.83 in an unpredictable way.[7]
Delta Sagittae is moving through the Galaxy at a speed of 9.8 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,800 and 35,300 light years from the center of the Galaxy.[16][better source needed]
Naming
[edit]Delta Sagittae (Latinized from δ Sagittae, abbreviated Delta Sge, δ Sge) is the star's Bayer designation.
In Chinese astronomy, 左旗 (Zuǒ Qí), meaning Left Flag, refers to an asterism consisting of δ Sagittae, α Sagittae, β Sagittae, ζ Sagittae, γ Sagittae, 13 Sagittae, 11 Sagittae, 14 Sagittae and ρ Aquilae. Consequently, the Chinese name for δ Sagittae itself is 左旗三 (Zuǒ Qí sān, English: the Third Star of Left Flag.)[17] The IAU Working Group on Star Names adopted the name Zuoqi for δ Sagittae A on 18 June 2026, after the Chinese constellation.[14]
Notes
[edit]- ↑ calculated from a sin i divided by the sine of inclination.
References
[edit]- 1 2 3 4 5 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.
- 1 2 3 "* del Sge". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 February 2017.
- ↑ Calculated from subtracting magnitudes.
- 1 2 3 4 5 6 7 8 Eaton, Joel A.; Hartkopf, William I.; McAlister, Harold A.; Mason, Brian D. (1995). "Winds and accretion in delta Sagittae". Astronomical Journal. 109 (4): 1856–1866. Bibcode:1995AJ....109.1856E. doi:10.1086/117412.
- 1 2 Schröder, K.-P.; Cuntz, M. (2007). "A critical test of empirical mass loss formulas applied to individual giants and supergiants". Astronomy and Astrophysics. 465 (2): 593–601. arXiv:astro-ph/0702172. Bibcode:2007A&A...465..593S. doi:10.1051/0004-6361:20066633. S2CID 55901104.
- 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- 1 2 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: B/GCVS. Bibcode:2009yCat....102025S.
- ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
- ↑ 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.
- 1 2 3 Pugh, T.; Gray, David F.; Griffin, R. F. (2015). "The orbit and variations of δ Sagittae". Monthly Notices of the Royal Astronomical Society. 454 (3): 2344–2352. Bibcode:2015MNRAS.454.2344P. doi:10.1093/mnras/stv2003. ISSN 0035-8711.
- ↑ 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.
- 1 2 Eggleton, Peter P.; Yakut, Kadri (2017). "Models for 60 double-lined binaries containing giants". Monthly Notices of the Royal Astronomical Society. 468 (3): 3533–3556. arXiv:1611.05041. doi:10.1093/mnras/stx598.
- 1 2 "IAU Catalog of Star Names". Retrieved 21 June 2026.
- ↑ Tabur, V.; Bedding, T. R.; Kiss, L. L.; Moon, T. T.; Szeidl, B.; Kjeldsen, H. (December 2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society. 400 (4): 1945–1961. arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x. S2CID 15358380.
- ↑ "Delta Sagittae (HIP 97365)". Archived from the original on 2013-01-02. Retrieved 2012-09-17.
- ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日 Archived 2011-05-21 at the Wayback Machine
