Y Sagittarii

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Y Sagittarii
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 21m 22.99s
Declination −18° 51′ 35.9″
Apparent magnitude (V) 5.76
Spectral type F8II
B−V color index 0.82[1]
Variable type Cepheid variable[1]
Radial velocity (Rv) -3.2[1] km/s
Proper motion (μ) RA: -3.12[1] mas/yr
Dec.: -7.12[1] mas/yr
Parallax (π) 2.64[1] mas
Distance 1293 ly
(396.4 pc)
Absolute magnitude (MV) -3.26
Mass 2.3 M
Radius 24 R
Luminosity 700 L
Temperature 6100[2] K
Metallicity [Fe/H] -0.02[3] dex
Age 330[2] Myr
Other designations
57 G. Sgr, HD 168608, HIP 89968, HR 6863
Database references

Y Sagittarii is a variable star in the constellation of Sagittarius. It is a Cepheid variable in apparent magnitude +5.77. This star is the third-brightest in this constellation after X Sagittarii and W Sagittarii. The measure of its parallax by Hubble Space Telescope puts Y Sagittarii to 1,293 light-years away from the Solar System.


The brightness ranges in Y Sagittarii's apparent magnitude varies from +5.25 and +6.24 in a period of 5.7736 days. The spectral type of this star is F8II, while the effective temperature is 5370 K. It has a radius 50 times larger than the Sun, its projected rotational velocity of 16 km / s and has an estimated mass six times that of the Sun. The star's metal content is similar to Sun, with an index of metallicity [Fe / H] = +0.05. For other metals tested, shows some overabundance of copper, zinc, yttrium and sodium, the level of the elements is almost double that of the Sun ([Na / H] = +0.27).[4]

Binary System[edit]

There is evidence that Y Sagittarii may be a spectroscopic binary. Has been suggested orbital period for the system in the order of 10,000 to 12,000 days. However, subsequent studies assume eccentricity zero for orbit, and they have failed to find the convincing orbital solution.

See also[edit]


  1. ^ a b c d e f "V* Y Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-09-17. 
  2. ^ a b "HIP 89968", Wolfram Alpha, retrieved 2012-09-17 
  3. ^ "Y Sagittarii, a white bright giant star in Sagittarius", Ashland Astronomy Studio, retrieved 2012-09-18 
  4. ^ J., Duncan (August 2013), "Changes in the spectrographic elements of Y Sagittarii", Astrophysical Journal, 56: 340–341, Bibcode:1922ApJ....56..340D, doi:10.1086/142708. 

External links[edit]