Beta Canum Venaticorum
Star in constellation Canes Venatici
From Wikipedia, the free encyclopedia
Beta Canum Venaticorum, proper name Chara, is the second-brightest star in the northern constellation of Canes Venatici. It is a nearby solar analog, located 27.6 light-years (8.5 parsecs) from the Sun based on its parallax. The star is faintly visible to the naked eye, at an apparent magnitude of +4.25. Along with the brighter star Cor Caroli, the pair form the "southern dog" in this constellation that represents hunting dogs.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canes Venatici |
| Right ascension | 12h 33m 44.54425s[1] |
| Declination | +41° 21′ 26.9214″[1] |
| Apparent magnitude (V) | 4.25[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | G0 V[3] |
| U−B color index | 0.04[4] |
| B−V color index | 0.58[4] |
| Astrometry | |
| Radial velocity (Rv) | +6.15±0.12[1] km/s |
| Proper motion (μ) | RA: −704.702[1] mas/yr Dec.: +292.155[1] mas/yr |
| Parallax (π) | 118.0266±0.1530 mas[1] |
| Distance | 27.63 ± 0.04 ly (8.47 ± 0.01 pc) |
| Absolute magnitude (MV) | 4.64[5] |
| Details | |
| Mass | 0.97±0.04[6] M☉ |
| Radius | 1.02±0.02[7] R☉ |
| Luminosity | 1.254±0.009[8] L☉ |
| Surface gravity (log g) | 4.41±0.04[8] cgs |
| Temperature | 6,013±91[8] K |
| Metallicity [Fe/H] | −0.2±0.01[8] dex |
| Rotational velocity (v sin i) | 2.9±0.4[9] km/s |
| Age | 3.4[6] to 7.1[5] Gyr |
| Other designations | |
| Chara, β CVn, 8 CVn, BD+42 2321, FK5 470, GJ 475, HD 109358, HIP 61317, HR 4785, SAO 44230, NGC 4530[10] | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
Nomenclature
β Canum Venaticorum (Latinised to Beta Canum Venaticorum) is the star's Bayer designation, abbreviated Beta CVn or β CVn. It has the Flamsteed designation 8 Canum Venaticorum.[10] The star was listed in the New General Catalogue as NGC 4530.[11][12]
The traditional name Chara, pronounced /ˈkɛərə/,[13][14] was originally applied to the "southern dog", but it later became used specifically to refer to Beta Canum Venaticorum. Chara (χαρά) means 'joy' in Greek[15] but ‘dear’ or ’beloved’ in Latin.[16] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] included a table of the first two batches of names approved by the WGSN; which included Chara for this star.
In Chinese, 常陳 (Cháng Chén), meaning Imperial Guards, refers to an asterism consisting of Beta Canum Venaticorum, Alpha Canum Venaticorum, 10 Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum, and 67 Ursae Majoris.[19] Consequently, the Chinese name for Beta Canum Venaticorum itself is 常陳四 (Cháng Chén sì, English: the Fourth Star of Imperial Guards.)[20]
Characteristics
Beta CVn has a stellar classification of G0 V, and so is a G-type main-sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[21] The spectrum of this star shows a very weak emission line of singly ionized calcium (Ca II) from the chromosphere, making it a useful reference star for a reference spectrum to compare with other stars in a similar spectral category.[22] (The Ca-II emission lines are readily accessible and can be used to measure the level of activity in a star's chromosphere.)
Beta CVn is considered to be slightly metal-poor,[8] which means it has a somewhat lower portion of elements heavier than helium when compared to the Sun. In terms of mass, age and evolutionary status, however, this star is very similar to the Sun.[23] As a result, it has been called a solar analog. It is about 3% less massive than the Sun,[2] with a radius 3% larger than the Sun's and 25% greater luminosity.[24][8]
The components of this star's space velocity are (U, V, W) = (–25, 0, +2) km/s.[23] In the past it was suggested that it may be a spectroscopic binary. However, further analysis of the data does not seem to bear that out.[25] In addition, a 2005 search for a brown dwarf in orbit around this star failed to discover any such companion, at least down to the sensitivity limit of the instrument used.[26]
Habitability
In 2006, astronomer Margaret Turnbull labeled Beta CVn as the top stellar system candidate to search for extraterrestrial life forms.[27] Because of its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun.[23] However, as of 2009, this star is not known to host planets.[2]
See also
- List of star systems within 25–30 light-years
- List of nearest G-type stars
- Beta Comae Berenices, a nearby similar star.