Stein 2051 is the nearest (
red dwarf +
white dwarf) separate binary system (
40 Eridani BC is located closer at 16.26 light-years,[13] but it is a part of a triple star system).
The brighter of these two stars is A (a
red dwarf), but the more massive is component B (a
white dwarf).
In 2017, Stein 2051 B was observed passing in front of a more distant star. The
bending of starlight by the
gravitational field of the nearer star allowed its mass to be directly measured. The estimated mass of Stein 2051 B is 0.675±0.051
M☉, which fits the expected range of a white dwarf with a carbon-oxygen core.[9]
^Passegger, V. M.; Bello-García, A.; Ordieres-Meré, J.; Caballero, J. A.; Schweitzer, A.; González-Marcos, A.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.; Béjar, V. J. S.; Cortés-Contreras, M.; Dreizler, S.; Hatzes, A. P.; Henning, Th.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Marfil, E.; Montes, D.; Morales, J. C.; Nagel, E.; Sarro, L. M.; Solano, E.; Tabernero, H. M.; Zechmeister, M. (2020), "The CARMENES search for exoplanets around M dwarfs", Astronomy & Astrophysics, 642: A22,
arXiv:2008.01186,
Bibcode:
2020A&A...642A..22P,
doi:
10.1051/0004-6361/202038787
^
abcGhosh, Samrat; Ghosh, Supriyo; Das, Ramkrishna; Mondal, Soumen; Khata, Dhrimadri (2020), "Understanding the physical properties of young M dwarfs: NIR spectroscopic studies", Monthly Notices of the Royal Astronomical Society, 493 (3): 4533–4550,
arXiv:2002.05762,
Bibcode:
2020MNRAS.493.4533K,
doi:10.1093/mnras/staa427
^Perryman; et al. (1997).
"HIP 21088". The Hipparcos and Tycho Catalogues. Retrieved 2014-11-23.
^Gliese, W. & Jahreiß, H. (1991).
"Gl 169.1". Preliminary Version of the Third Catalogue of Nearby Stars. Retrieved 2014-11-23.
^
abVan Altena W. F.; Lee J. T.; Hoffleit E. D. (1995).
"GCTP 986.01". The General Catalogue of Trigonometric Stellar Parallaxes (Fourth ed.). Retrieved 2014-11-23.
^Perryman; et al. (1997).
"HIP 19849". The Hipparcos and Tycho Catalogues. Retrieved 2014-11-21.