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Binary star system in the constellation Sagitta
δ Sagittae
Location of δ Sagittae (circled)
Observation data
Epoch
J2000
Equinox
J2000
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
Spectral type
M2II + B9.5V
[4]
U−B
color index
+0.98
[5]
B−V
color index
+1.40
[5]
Variable type
LB?
[6]
Astrometry
Radial velocity (Rv ) 2.5 ± 0.9
[7] km/s
Proper motion (μ)
RA: -6.514
[1]
mas /
yr
Dec.: 0.849
[1]
mas /
yr
Parallax (π) 5.9674 ± 0.2597
mas
[8]
Distance 550 ± 20
ly (168 ± 7
pc )
Absolute magnitude (MV ) −2.58
[9]
Orbit
[4]
Period (P) 10.11
yr
Semi-major axis (a) 0.051″
Eccentricity (e) 0.44
Inclination (i) 140.0°
Longitude of the node (Ω) 170.2°
Periastron
epoch (T) 1979.93
Argument of periastron (ω) (secondary)257.7°
Details δ Sge A
Mass 3.35+0.335 −0.30
[10]
M ☉
Radius 108
[11]
R ☉
Luminosity 1,888 - 1,923
[11]
L ☉
Surface gravity (log g ) 0.74 ± 0.10
[10]
cgs
Temperature 3,660± 170
[11]
K δ Sge B
Mass 2.9
[4]
M ☉
Radius 2.6
[4]
R ☉ Luminosity 63
[4]
L ☉
Temperature 10000
[4]
K
Other designations
δ Sagittae,
7 Sagittae,
BD +18 4240,
CCDM J19474+1832AB,
FK5 743,
GC 27391,
HD 187076,
HIP 97365,
HR 7536,
IDS 19429+1817 AB,
PPM 136976,
SAO 105259,
WDS J19474+1832AB
Database references
SIMBAD
data
Delta Sagittae (Delta Sge , δ Sagittae , δ Sge ) 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]
A
visual band
light curve for Delta Sagittae, plotted from data published by Tabur et al. (2009)
[12]
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.
[6]
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.
[13] [
better source needed ]
Naming
In
Chinese , 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 .)
[14]
References
^
a
b
c
d
e
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
"* del Sge" .
SIMBAD .
Centre de données astronomiques de Strasbourg . Retrieved 23 February 2017 .
^ Calculated from subtracting magnitudes.
^
a
b
c
d
e
f
g
h 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 .
^
a
b Mermilliod, J.-C. (1986).
"Compilation of Eggen's UBV data, transformed to UBV (unpublished)" . Catalogue of Eggen's UBV Data .
Bibcode :
1986EgUBV........0M .
^
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 : 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 .
^
a
b 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 .
^
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 .
^ 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)
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