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1RXS J160929.1−210524
1RXS J160929.1−210524 (also known as GSC 6213-1358 or PZ99 J160930.3−210459) is a pre-main-sequence star approximately 456 light-years away in the constellation of Scorpius. The star was identified as a member of the Upper Scorpius subgroup of the Scorpius–Centaurus association by Thomas Preibisch and coauthors in 1998, and originally assigned an age of years old based on its group membership. A more recent analysis of the ages of the stars in the Upper Scorpius group pegs its average age at 11 million years. Stellar characteristics This star was identified as a young object belonging to the Upper Scorpius subgroup of the Scorpius–Centaurus association in two papers published in 1998 and 1999, based on its lithium abundance, X-ray emission, and position in the H–R diagram. The spectrum of 1RXS J160929.1-210524 reveals it to be cooler than the Sun with a stellar classification, spectral type that has been estimated at K7 or M0, so the star can be considered an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoch (astronomy)
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodies) can be used to generate an ephemeris, a table of values giving the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |