The location of the multiple star system 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 object is compared to the celestial equator and is expressed in degrees. For HD 202772A, the location is 21 18 47.8741850020 and -26 36 58.055229725 .
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 -57.56 milliarcseconds/year towards the north and 23.24 milliarcseconds/year east if we saw them in the horizon.
The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -17.71 km/s . 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.
|Primary / Proper / Traditional Name||HD 202772A|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Multiple Star System|
|Right Ascension (R.A.)||21 18 47.8741850020|
|Declination (Dec.)||-26 36 58.055229725|
|Distance from Earth||6.17 Parallax (milliarcseconds)|
|529.01 Light Years|
|33,453,855.82 Astronomical Units|
|Proper Motion Dec.||-57.56 milliarcseconds/year|
|Proper Motion RA.||23.24 milliarcseconds/year|
|Radial Velocity||-17.71 km/s|
|Associated / Clustered Stars||HD 202772|
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