HD 140283
 HD 140283 |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Libra |
| Right ascension | 15h 43m 3.10s |
| Declination | −10° 56′ 00.6″ |
| Apparent magnitude (V) | 7.223 |
| Astrometry | |
| Radial velocity (Rv) | −169 km/s |
| Proper motion (μ) |
RA: −1114.93 mas/yr Dec.: −304.36 mas/yr |
| Parallax (π) | 17.15 ± 0.14 mas |
| Distance | 190.1 ± 1.5 ly (58.30 ± 0.48pc) |
| DetailsSIMBAD | |
| Radius | 1.4 R☉ |
| Luminosity | 3.83 L☉ |
| Temperature | 5777 ± 55 K |
| Metallicity [Fe/H] | −2.40 ± 0.10 dex |
| Rotational velocity (v sin i) | ≤ 3.9 km/s |
| Age | 14.46 ± 0.8 (minimum 13.66) Gyr |
| Database references | |
| SIMBAD | data |
HD 140283, informally nicknamed Methuselah star, is a metal-poor subgiant star about 190 light years away from the Earth in the constellation Libra. Its apparent magnitude is 7.223. The star has been known to astronomers for over a century as a high-velocity star, and an early spectroscopic analysis by Chamberlain and Aller found it to have a substantially lower metal content than the Sun. Modern spectroscopic analyses find an iron content about a factor of 250 lower than that of the Sun. It is one of the closest Population II stars to us.
Because HD 140283 is neither on the main sequence nor a red giant, its position in the Hertzsprung-Russell diagram can be interpreted with theoretical models of stellar evolution to infer the stellar age. For field stars (as opposed to stars in clusters) it is rare to know a star's luminosity, surface temperature and composition precisely enough to get a well-constrained value for the stellar age; because of their relative scarcity, this is even rarer for a Population II star like HD 140283. One recent study used the Fine Guidance Sensors of NASA's Hubble Space Telescope to measure a precise parallax (and therefore distance and luminosity) for the star, and employ this information to estimate an age for the star of 14.46 ± 0.8 billion years. Due to the uncertainty in the value, this age for the star may not conflict with the age of the Universe determined by the Planck satellite, 13.799 ± 0.021. Once dubbed the "Methuselah Star" by the popular press due to its age, the star must have formed soon after the Big Bang and is one of the oldest stars known. Accurate determinations of the ages of metal-poor stars, such as HD 140283 and those in globular clusters, set a lower limit for the possible age of the Universe independent of cosmological theory or observations.
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