SDSS J0815+4729
Ultra-low metallicity star in the constellation Lynx
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SDSS J081554.26+472947.5, often abbreviated to its partial coordinates, J0815+4729, 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 a temperature of 6,215 K. It is at a distance of 7,500 light years (2.3 kiloparsecs) from the Sun, and is 33,000 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.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx[1] |
| Right ascension | 08h 15m 54.26778s[2] |
| Declination | +47° 29′ 47.6013″[2] |
| Apparent magnitude (V) | 16.9[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | F5V[5] |
| Astrometry | |
| Radial velocity (Rv) | −108[5] km/s |
| Proper motion (μ) | RA: −14.257 mas/yr[2] Dec.: −24.214 mas/yr[2] |
| Parallax (π) | 0.4089±0.0685 mas[2] |
| Distance | approx. 8,000 ly (approx. 2,400 pc) |
| Details | |
| Mass | 1.18[6] M☉ |
| Radius | 0.72[6] R☉ |
| Luminosity | 0.67[6] L☉ |
| Surface gravity (log g) | 4.80[6] cgs |
| Temperature | 6,142±118[4] K |
| Metallicity [Fe/H] | −5.49±0.14[7] dex |
| Other designations | |
| SDSS J081554.26+472947.5, Gaia DR2 931227322991970560 | |
| Database references | |
| SIMBAD | data |
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 a collapsing supernova remnant.[7]