Arkab Posterior (HIP 95294)

Arkab Posterior is a white subgiant star in the constellation Sagittarius. At 134 light years away, it shines at an apparent visual magnitude of 4.27. The star's age is estimated to be 1 billion years but is certainly no less than 900 million years and no greater than 1.1 billion years. The iron abundance of Arkab Posterior is -0.17 (67.6% of the Sun). It is moving through the Galaxy at a speed of 28.4 km/s relative to the Sun. Its projected Galactic orbit carries it between 22,800 and 30,000 light years from the center of the Galaxy. It came closest to the Sun 949,000 years ago when it had brightened to magnitude 3.62 from a distance of 100 light years.

Sky position: RA 19h 23.2m, Dec -44 48'

Common designations: Arkab Posterior, Beta-2 Sagittarii, HIP 95294, HD 181623, HR 7343

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Brightest stars in Sagittarius:
(list all)

9

|    3.17

)   Phi Sagittarii

10

|    3.32

)   Tau Sagittarii

11

|    3.52

)   Xi-2 Sagittarii

12

|    3.76

)   Manubrij

13

|    3.84

)   Polis

14

|    3.92

)   Rho-1 Sagittarii

15

|    3.96

)   Arkab Prior

16

|    3.96

)   Rukbat

17

|    4.12

)   Iota Sagittarii

18

|    4.27

)   Arkab Posterior

19

|    4.37

)   Theta-1 Sagittarii

20

|    4.43

)   Terebellum

21

|    4.52

)   Upsilon Sagittarii

22

|    4.53

)   X Sagittarii

23

|    4.54

)   Terebellum

24

|    4.55

)   HR 6766

25

|    4.59

)   52 Sagittarii

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


Galactic Orbit of Arkab Posterior

(compared to the Sun)

Eccentricity: 13.6% vs. 16.0%

Angle φ : 53.6 vs. 26.0

Semi-major axis : 8,108 pc vs. 8,686 pc

Semi-minor axis: 8,032 pc vs. 8,574 pc

Focus-to-center: 1,103 pc vs. 1,388 pc

Semilatus rectum : 7,958 pc vs. 8,464 pc

Perigalacticon: 7,005 pc vs. 7,297 pc

Apogalacticon: 9,210 pc vs. 10,074 pc
 


Some Tabulated XHIP Data for Arkab Posterior
(see also: SIMBAD)

Astrometry
2007A&A...474..653V
  Position Proper Motion
Right Ascension: 290.80441927 0.17 mas 93.53 0.24 mas/yr.
Declination: -44.79964773 0.10 mas -54.15 0.16 mas/yr.
     
Galactic Longitude: 353.28292469 -28.02 mas/yr.
Galactic Latitude: -24.11619348 -104.37 mas/yr.

Parallax: 24.31 0.19 mas


Spectrography

Spectral Type: F0IV 1989ApJS...69..301G.

Radial Velocity: 19.00 4.10 km/s [A rating] 2006AstL...32..759G.

Iron Abundance [Fe/H]: -0.17 0.15 dex  2009A&A...501..941H.
 



Photometry
 
band magnitude Abs. Mag.
U
B 4.62 1.55
V 4.27 1.20
R
I 3.89 0.82
J 3.18 0.11
H 2.94 -0.14
K 2.93 -0.14

  B-V: +0.35       V-I: +0.38


Derivations

Heliocentric distance: 41.13 pc (0.8% margin of error)

Galactocentric distance: 7,363 pc

Transverse velocity: 21.1 km/s

3D heliocentric position and motion:

toward:   

Galactic center Galactic rotation North Galactic Pole
Position ( X, Y, Z) 37.3 pc -4.4 pc -16.8 pc
Velocity (U, V, W) 8.3 km/s -6.5 km/s -26.3 km/s

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