The Id of the star in the Henry Draper catalogue is HD173140.
YY Sagittarius has alternative name(s) :- YY Sgr.
More details on star alternative names can be found at Star Names .
The location of the star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For YY Sagittarius, the location is 18 44 35.8395514834 and -19 23 23.033010890 .
All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -0.75 miliarcseconds/year towards the north and -0.58 miliarcseconds/year east if we saw them in the horizon. . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.
YY Sagittarius has a spectral type of B8/9II D. This means the star is a blue luminous giant star.
The Parallax of the star is given as 0.99 which gives a calculated distance to YY Sagittarius of 3299.24 light years from the Earth or 1011.53 parsecs. It would take a spaceship travelling at the speed of light, 3299.24 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is roughly 208,641,585.63 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.
The star is a eclipsing binary sys Beta Persei (Algol) variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted.
|Primary / Proper / Traditional Name||YY Sagittarius|
|Alternative Names||YY Sgr, HD 173140|
|Spectral Type||B8/9II D|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Luminous Giant Star|
|Right Ascension (R.A.)||18 44 35.8395514834|
|Declination (Dec.)||-19 23 23.033010890|
|Distance from Earth||0.99 Parallax (milliarcseconds)|
|3299.24 Light Years|
|208,641,585.63 Astronomical Units|
|Proper Motion Dec.||-0.75 milliarcseconds/year|
|Proper Motion RA.||-0.58 milliarcseconds/year|
|Variable Star Class||Eclipsing binary sys|
|Variable Star Type||Beta Persei (Algol)|