| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 21m 22.98643s[2] |
| Declination | −18° 51′ 36.0018″[2] |
| Apparent magnitude (V) | 5.76[3] |
| Characteristics | |
| Spectral type | F8 II[4] |
| B−Vcolor index | 0.67±0.02[3] |
| Variable type | Cepheid variable[4] |
| Astrometry | |
| Radial velocity (Rv) | −1.4±2.3[3] km/s |
| Proper motion (μ) | RA: −3.12[2]mas/yr Dec.: −7.12[2]mas/yr |
| Parallax (π) | 2.13±0.29 mas[5] |
| Distance | approx. 1,500 ly (approx. 470 pc) |
| Absolute magnitude (MV) | −2.06[3] |
| Details | |
| Surface gravity (log g) | 1.80[4] cgs |
| Temperature | 5,967±26[4] K |
| Age | 330[6] Myr |
| Other designations | |
| 57 G. Sgr,Y Sgr,BD−18° 4926,HD 168608,HIP 89968,HR 6863[7] | |
| Database references | |
| SIMBAD | data |
Y Sagittarii is avariable star in the constellation of Sagittarius. It is aCepheid variable with anapparent magnitude that ranges around +5.77. The measure of itsparallax byHubble Space Telescope puts Y Sagittarii to 1,293light-years away from theSolar System.
The brightness ranges in Y Sagittarii'sapparent magnitude varies from +5.25 and +6.24 in a period of 5.7736 days. The spectral type of thisstar is F8II, while the effective temperature is 5370 K. It has a radius 50 times larger than theSun, while its projected rotational velocity of 16 km / s and it has an estimated mass six times that of the Sun. The star's metal content is similar toSun, with an index of metallicity [Fe / H] = +0.05. For other metals tested, it shows some overabundance ofcopper,zinc,yttrium andsodium; the level of the elements is almost double that of the Sun ([Na / H] = +0.27).[8]
There is evidence that Y Sagittarii may be aspectroscopic binary. It has been suggested that theorbital period for the system is on the order of 10,000 to 12,000 days. However, subsequent studies assumeeccentricity zero for orbit, and they have failed to find a convincing orbital solution. Instead, it appears to be a distant visual companion.[9]
