| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 11h 40m 28.48381s[1] |
| Declination | +69° 00′ 30.5995″[1] |
| Apparent magnitude (V) | 8.70 |
| Characteristics | |
| Spectral type | G5V[2] |
| U−Bcolor index | 0.155 |
| B−Vcolor index | 0.647 ± 0.014[1] |
| Variable type | none |
| Astrometry | |
| Radial velocity (Rv) | 5.4[3] km/s |
| Proper motion (μ) | RA: –126.96[1]mas/yr Dec.: –2.13[1]mas/yr |
| Parallax (π) | 15.68±0.67 mas[1] |
| Distance | 208 ± 9 ly (64 ± 3 pc) |
| Absolute magnitude (MV) | 4.81 |
| Details | |
| Mass | 1.02 ± 0.02[4] M☉ |
| Radius | 0.99 R☉ |
| Luminosity | 0.99[5] L☉ |
| Surface gravity (log g) | 4.409[5] cgs |
| Temperature | 5795[5] K |
| Metallicity [Fe/H] | 0.02[5] dex |
| Age | ~7.1[6] Gyr |
| Other designations | |
| HD 101364,BD+69 620,SAO 15590. | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HIP 56948 (also known asHD 101364) is asolar twin star of typeG5V.[2] It is one of the most Sun-like stars yet known in terms of size, mass, temperature, and chemical makeup. The Sun is about 4.6 billion years old, and HIP 56948 is believed to be about 7.1 billion years old. Both stars are between a third and a halfway through their life on themain sequence.[6][7]
It is 208light years away in the constellation ofDraco,[8] lying about halfway betweenPolaris andDubhe on the celestial sphere.[9] Astronomers have looked for planets in the system, so far without finding any. These observations suggest that the star does not have anyhot Jupiters.[10]
Jorge Meléndez of theAustralian National University andIván Ramírez of theUniversity of Texas analysed the star in 2007 using the 2.7 metreHarlan J. Smith telescope atMcDonald Observatory.[11]
Most other solar analogs such as18 Scorpii are unlike the Sun in that they have several times thelithium abundance. HIP 56948 is among the best candidates for asolar twin because of the known possible contenders, its lithium abundance most resembles that of the Sun.[5][12] A 2009 high-dispersion spectroscopic study from the Astronomical Society of Japan confirms this.[5]
In the abstract to their paper, the star's discoverers say:[7]
For more than a decade,18 Sco (HD 146233) has been considered the star that most closely resembles theSun, even though significant differences such as itsLi content, which is about 3 times solar, exist. Using high-resolution, high-S/N spectra obtained atMcDonald Observatory, we show that the stars HIP 56948 andHIP 73815 are very similar to the Sun in both stellar parameters and chemical composition, including a low Li abundance, which was previously thought to be peculiar in the Sun. HIP 56948, in particular, has stellar parameters identical to solar within the observational uncertainties, being thus the bestsolar twin known to date. HIP 56948 is also similar to the Sun in its lack ofhot Jupiters. Considering the age of this star (~1 ± 1 Gyr older than the Sun)[Notes 1] and its location and orbit around theGalaxy, ifterrestrial planets exist around it, they may have had enough time to develop complex life, making it a prime target forSETI.
— Jorge Meléndez and Iván Ramírez, 8 October 2007
