HE0107-5240
HE0107-5240 is a Population II star that has almost no metal. This kind of star is called a metal-poor star. It is close to 36000 light-years away from Earth. It is one of the most metal-poor stars known in our galaxy, with a metallicity of -5.2;[3] This means it has just 1/160000 of the metal that the Sun has. Because of its very low metallicity, it is believed to be one of the earliest Population II stars to have formed. If so, then it is also very old, with an age of roughly 13 billion years. Because the star still has a bit of metal, it does not belong to the first generation of stars (the hypothetical Population III). These stars changed the pure hydrogen, helium, and lithium formed by the Big Bang into heavier elements, such as carbon, oxygen, and metals.
 The ultra-metal-poor star HE0107-5240 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Phoenix |
| Right ascension | 01h 09m 29.1s[1] |
| Declination | −52° 24′ 20″ |
| Apparent magnitude (V) | 15.86 |
| Astrometry | |
| Proper motion (μ) | RA: +2.357[2] mas/yr Dec.: −3.826[2] mas/yr |
| Parallax (π) | 0.1064 ± 0.0195[2] mas |
| Distance | 36000 ly |
| Details | |
| Mass | 1.789[2] M☉ |
| Radius | 3.7[2] R☉ |
| Luminosity | 14[2] L☉ |
| Temperature | 5,765[2] K |
| Metallicity [Fe/H] | −5.3 [3] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
The star is small for a star that formed in the early universe. This explains why it is so old, as bigger stars die more quickly. To help explain why this star is so small, people think it was once part of a binary system.[4] [5]
References
change- ↑ A. Udalski; G. Pietrzynski; M. Szymanski; M. Kubiak; K. Zebrun; I. Soszynski; O. Szewczyk; L. Wyrzykowski (June 2003). "The Optical Gravitational Lensing Experiment. Additional Planetary and Low-Luminosity Object Transits from the OGLE 2001 and 2002 Observational Campaigns". Acta Astronomica. 53: 133–149. arXiv:astro-ph/0306444. Bibcode:2003AcA....53..133U.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Christlieb, N.; Gustafsson, B.; Korn, A. J.; Barklem, P. S.; Beers, T. C.; Bessell, M. S.; Karlsson, T.; Mizuno-Wiedner, M. (2004). "HE 0107-5240, a Chemically Ancient Star. I. A Detailed Abundance Analysis". The Astrophysical Journal. 603 (2): 708. arXiv:astro-ph/0311173. Bibcode:2004ApJ...603..708C. doi:10.1086/381237. S2CID 7110470.
- ↑ Lau, Herbert H. B.; Stancliffe, Richard J.; Tout, Christopher A. (2007). "Carbon-rich extremely metal poor stars: signatures of Population III asymptotic giant branch stars in binary systems". MNRAS. 378 (2): 563–568. arXiv:astro-ph/0703685. Bibcode:2007MNRAS.378..563L. doi:10.1111/j.1365-2966.2007.11773.x. S2CID 14996538.
- ↑ Suda, Takuma; Aikawa, Masayuki; Machida, Masahiro N.; Fujimoto, Masayuki Y.; Iben, Icko Jr. (2004). "Is HE 0107-5240 A Primordial Star? The Characteristics of Extremely Metal-Poor Carbon-Rich Stars". Astrophysical Journal. 611 (1): 476–493. arXiv:astro-ph/0402589. Bibcode:2004ApJ...611..476S. doi:10.1086/422135. S2CID 13040221.
