It is 29.9
light-years (9.2
parsecs) from the Sun as measured by the
Gaia spacecraft,[1] which, as the distance is nearly 10 parsecs, means its
absolute magnitude is almost equal to its
apparent magnitude. It is a member of the
galactic halo; such stars account for only 0.1 to 0.2 percent of the stars near the
Sun. Like most halo stars, it has a low abundance of elements other than hydrogen and helium—what astronomers term a
metal-poor star.[12]
Once suspected of being a
binary star with a period of 175 days, current consensus is that it is single. Previous suspected observations of a stellar companion were probably "superflares"—analogous to the Sun's
solar flares, but hundreds to millions of times more energetic.[12][13] It had one of the first nine identified
superflares.
Proper motion
When discovered, it had the highest
proper motion of any star known, replacing
61 Cygni in that department. Later it dropped to second place after the discovery of
Kapteyn's Star, and still later to third place after the discovery of
Barnard's Star. It is considerably farther away than either of those stars, however, which means its transverse velocity is greater.
^Johnson, H. L.; Morgan, W. W. (1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". Astrophysical Journal. 117: 313–352.
Bibcode:
1953ApJ...117..313J.
doi:
10.1086/145697.
^Kukarkin, B. V.; et al. (1981). "Catalogue of suspected variable stars". Nachrichtenblatt der Vereinigung der Sternfreunde. Moscow, USSR: Academy of Sciences.
Bibcode:
1981NVS...C......0K.
^Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto:
International Astronomical Union.
Bibcode:
1967IAUS...30...57E.
^Takeda, Genya; Ford, Eric B.; Sills, Alison; Rasio, Frederic A.; Fischer, Debra A.; Valenti, Jeff A. (February 2007). "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog". The Astrophysical Journal Supplement Series. 168 (2): 297–318.
arXiv:astro-ph/0607235.
Bibcode:
2007ApJS..168..297T.
doi:
10.1086/509763.
S2CID18775378.