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HE0107-5240

The ultra-metal-poor star HE0107-5240
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Phoenix
Right ascension	01 09 29.1
Declination	−52° 24′ 20″
Apparent magnitude (V)	15.86
Astrometry
Proper motion (μ)	RA: +2.357 mas/yr Dec.: −3.826 mas/yr
Parallax (π)	0.1064 ± 0.0195 mas
Distance	36000 ly
Details
Mass	1.789 M☉
Radius	3.7 R☉
Luminosity	14 L☉
Temperature	5,765 K
Metallicity	−5.3  dex
Other designations
HE 0107-5240, 2MASS J01092916-5224341.
Database references
SIMBAD	data

HE0107-5240 is an extremely metal-poor Population II star, located roughly 36000 light-years away from Earth. It is one of the most metal-poor stars known in our Galaxy, with a metallicity = −5.2±0.2; i.e. 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 is not completely metal-free, it does not belong to the first generation of stars (the hypothetical Population III). These stars converted the pristine hydrogen, helium, and lithium formed by the Big Bang into heavier elements, such as carbon, oxygen, and metals.

The star is relatively small for a star of the early universe, which accounts for its old age: massive stars die quickly. To help explain why this star is so small, it is hypothesized it was once part of a binary star system.

HE0107-5240 was found by Norbert Christlieb and colleagues at the University of Hamburg in Germany as a byproduct of the Hamburg/ESO Survey for faint quasars with the 1m ESO Schmidt telescope. Follow-up observations were made at the Siding Spring 2.3 m Telescope and high-resolution spectra were taken at the European Southern Observatory in Chile, using one of the units of the Very Large Telescope. In 2005, a second star with an even smaller iron abundance, HE 1327-2326 (=-5.4), was found, also in the Hamburg/ESO survey. In 2014 an even more metal poor star was announced: SMSS J031300.36−670839.3.

See also

Other ultra low metallicity / ultra metal poor stars

• Cayrel's Star
• HE 1327-2326
• SDSS J102915+172927

References

1. 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. ^ 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. ^ 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.
4. 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.
5. 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.
6. S. C. Keller; M. S. Bessell; A. Frebel; A. R. Casey; M. Asplund; H. R. Jacobson; K. Lind; J. E. Norris; D. Yong, A. Heger; Z. Magic; G. S. Da Costa; B. P. Schmidt; P. Tisserand (2014). "A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36−670839.3". Nature. 506 (7489): 463–466. arXiv:1402.1517. Bibcode:2014Natur.506..463K. doi:10.1038/nature12990. ISSN 0028-0836. PMID 24509711. S2CID 4457295.

• Christlieb N., Bessell M.S., Gustafsson B., Korn A., Barklem P.S., Karisson T., Mizuno-Wiedner M., Rossi S., "A stellar relic from the early Milky Way", Nature, 419, 904-906 (2002)

External links

• SIMBAD-Entry (SIMBAD)
• Hamburg/ESO survey (Christlieb+, 2008)
• Relic Star Found, Pointing Way to Dawn of Time (Space.com)
• VLT UVES Observes Most Metal-Deficient Star Known (European Southern Observatory)
• he0107-5240

v t e Constellation of Phoenix
List of stars in Phoenix Phoenix in Chinese astronomy
Stars	Bayer α (Ankaa) β γ δ ε ζ (Wurren) η θ ι κ λ λ μ ν ξ π ρ σ τ υ φ χ ψ ω Variable RV SX YZ AD AE AI AW AZ BB BD HR 6 23 73 109 111 120 140 148 162 171 198 202 209 229 299 350 408 411 443 447 519 524 537 574 588 632 636 659 686 698 706 8910 8920 8929 8959 8993 9001 9046 9077 9082 HD 2039 5388 6434 (Nenque) 8535 9895 11421 13218 13387 223549 224782 Other CD-44 170 BPM 30551 HE 0107-5240 NGC 405 WASP-4 WASP-5 WASP-18 WASP-29 WASP-96 WD 2359-434
Exoplanets HD 142 b HD 2039 b HD 6434 b HD 8535 b HIP 65Ab WASP-4b WASP-5b WASP-18b WASP-96b
Galaxies	NGC 25 28 31 37 87 88 89 92 98 119 159 212 238 312 319 322 323 324 328 348 368 454 482 625 Other Phoenix Dwarf
Galaxy clusters El Gordo Phoenix Cluster Robert's Quartet
Category

• Phoenix (constellation)
• Population II stars