J0815+4729

J0815+4729, abbreviated from SDSS J081554.26+472947.5, is a star with an ultra-low metallicity in the constellation of Lynx. It also has a relatively high concentration of carbon.[4] The surface of the star has temperature 6,215 K. It is at a distance of 7,500 light years (2.3 kiloparsecs) from the Sun, and is 33,00 light-years (10 kiloparsecs) from the Galactic Center.[4] Its [Fe/H] was first believed to be below –5.8 dex, making it the lowest metallicity un-evolved star detected.,[4] but was revised to -5.49 dex in 2020.[5]

J0815+4729
Observation data
Epoch J2000      Equinox J2000
Constellation Lynx
Right ascension 8h 15m 54.268s[1]
Declination 47° 29m 47.573s[1]
Characteristics
Evolutionary stage main-sequence star
Spectral type F5V[2]
Astrometry
Radial velocity (Rv)-108[2] km/s
Proper motion (μ) RA: -14.154[2] mas/yr
Dec.: -24.229[2] mas/yr
Parallax (π)0.4441 ± 0.0837[3] mas
Distanceapprox. 7,000 ly
(approx. 2,300 pc)
Details[4]
Surface gravity (log g)4.7 ± 0.6 cgs
Temperature6142 ± 118 K
Metallicity [Fe/H]−5.49±0.14[5] dex
Other designations
SDSS J081554.26+472947.5, Gaia DR2 931227322991970560
Database references
SIMBADdata

J0815+4729's ratio of carbon to iron, [C/Fe] is at least 5.0 dex.[4] The star is also heavily enriched in nitrogen and oxygen, originating from primordial gas cloud contaminated by single zero-metallicity supernova. The lack of heavy elements, including iron, is explained by these mostly falling back to collapsing supernova remnant.[5]

References
  1. Ahn, C. P.; et al. (2012). "The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey". The Astrophysical Journal Supplement. 203 (2): 13. arXiv:1207.7137. Bibcode:2012ApJS..203...21A. doi:10.1088/0067-0049/203/2/21. 21.
  2. "SDSS J081554.26+472947.5". SIMBAD. Centre de données astronomiques de Strasbourg.
  3. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. Aguado, David S; Hernández, Jonay I. González; Prieto, Carlos Allende; Rebolo, Rafael (2018). "J0815+4729: A Chemically Primitive Dwarf Star in the Galactic Halo Observed with Gran Telescopio Canarias". The Astrophysical Journal. 852: L20. arXiv:1712.06487. Bibcode:2018ApJ...852L..20A. doi:10.3847/2041-8213/aaa23a.
  5. The extreme CNO-enhanced composition of the primitive iron-poor dwarf star J0815+4729, 2020, arXiv:2001.07257


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