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The position of Beta Gruis in the Grus constellation. |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Grus |
| Right ascension | 22h 42m 40.1s[1] |
| Declination | -46° 53′ 05″[1] |
| Apparent magnitude (V) | 2.13[1] |
| Characteristics | |
| Spectral type | M5 III[1] |
| U−B color index | 1.67 |
| B−V color index | 1.60 |
| Variable type | LC[2] |
| Astrometry | |
| Radial velocity (Rv) | 1.6 ±0.9[1] km/s |
| Proper motion (μ) | RA: 135.68 ±0.70[1] mas/yr Dec.: -4.51 ±0.45[1] mas/yr |
| Parallax (π) | 19.17 ± 0.75 mas |
| Distance | 170 ± 7 ly (52 ± 2 pc) |
| Absolute magnitude (MV) | -1.52 |
| Other designations | |
| Database references | |
| SIMBAD | data |
Beta Gruis (β Gruis, β Gru) is the second brighest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish:[3] it, with α, δ, θ. ι, and λ Gru, belonged to Piscis Austrinus in traditional Arabic astronomy.[4]
The estimated mass is about three times that of the Sun, and it has a surface temperature of approximately 3,400 K, just over half the surface temperature of the sun. This low temperature accounts for the star's dull red color. The total luminosity is about 3,800 times that of the Sun, and it has an estimated radius of 0.8 astronomical units (120,000,000 km), which is about 100 times that of the Sun.
Beta Gruis is a type LC slow irregular variable star that varies in magnitude from 2.0 to 2.3.[2]
Beta Gruis played a crucial part in Perth Observatory's tracking of comet 2000 WM1 LINEAR in December 2001.[5]
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