21 Sagittarii (HIP 90289)

21 Sagittarii is an orange giant star in the constellation Sagittarius. At 406 light years away, it shines at an apparent visual magnitude of 4.81. 21 Sagittarii is a multiple-star system. It is moving through the Galaxy at a speed of 21.4 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,700 and 25,700 light years from the center of the Galaxy.

Sky position: RA 18h 25.4m, Dec -20 32.4'

Common designations: 21 Sagittarii, HIP 90289, HD 169420, HR 6896

Stars of the Northern Hemisphere

The Modern Guide to the Stars


Brightest stars in Sagittarius:
(list all)

22

|    4.53

)   X Sagittarii

23

|    4.54

)   Terebellum

24

|    4.55

)   HR 6766

25

|    4.59

)   52 Sagittarii

26

|    4.66

)   Nash

27

|    4.66

)   HR 6842

28

|    4.70

)   Terebellum

29

|    4.74

)   4 Sagittarii

30

|    4.77

)   HR 7652

31

|    4.81

)   21 Sagittarii

32

|    4.84

)   Terebellum

33

|    4.86

)   HR 7029

34

|    4.86

)   Ain al Rami

35

|    4.86

)   Psi Sagittarii

36

|    4.87

)   56 Sagittarii

37

|    4.88

)   43 Sagittarii

38

|    4.96

)   11 Sagittarii

Location of 21 Sagittarii circled
Map detail from Stars of the Northern Hemisphere
Hover over other bright stars to identify or click to jump.


Galactic Orbit of 21 Sagittarii

(compared to the Sun)

Eccentricity: 4.0% vs. 16.0%

Angle φ : 12.1 vs. 26.0

Semi-major axis : 7,573 pc vs. 8,686 pc

Semi-minor axis: 7,567 pc vs. 8,574 pc

Focus-to-center: 301 pc vs. 1,388 pc

Semilatus rectum : 7,561 pc vs. 8,464 pc

Perigalacticon: 7,272 pc vs. 7,297 pc

Apogalacticon: 7,874 pc vs. 10,074 pc
 


Some Tabulated XHIP Data for 21 Sagittarii
(see also: SIMBAD)

Astrometry
2007A&A...474..653V
  Position Proper Motion
Right Ascension: 276.33764784 0.75 mas 20.10 3.40 mas/yr.
Declination: -20.54160913 0.46 mas -22.70 3.20 mas/yr.
     
Galactic Longitude: 11.73608689 -10.80 mas/yr.
Galactic Latitude: -3.74636851 -28.33 mas/yr.

Parallax: 7.95 0.72 mas


Spectrography

Spectral Type: K1/2 III 1988MSS...C04....0H.

Radial Velocity: -11.80 0.80 km/s [A rating] 2006AstL...32..759G.

Iron Abundance [Fe/H]: n/a
 



Photometry
 
band magnitude Abs. Mag.
U
B 6.12 0.64
V 4.81 -0.67
R
I 3.74 -1.73
J 2.22 -3.26
H 1.55 -3.92
K 1.42 -4.06

  B-V: +1.31       V-I: +1.07


Derivations

Heliocentric distance: 124.56 pc (9.1% margin of error)

Galactocentric distance: 7,278 pc

Transverse velocity: 17.9 km/s

3D heliocentric position and motion:

toward:   

Galactic center Galactic rotation North Galactic Pole
Position ( X, Y, Z) 121.7 pc 25.3 pc -8.1 pc
Velocity (U, V, W) -11.3 km/s -8.9 km/s -15.9 km/s

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