Zeta Cancri
| ζ Cancri | |
|---|---|
|
Observation dates equinox : J2000.0 , epoch : J2000.0 |
|
| Constellation | Cancer |
| Right ascension | 08 h 12 m 12.9 s |
| declination | + 17 ° 38.9 ′ 0 ″ |
|
Overall apparent visual brightness |
4.7 likes |
| Astrometry | |
| Radial velocity | approx. −6 km / s |
| parallax | (39.9 ± 0.8) mas |
| distance | (25.1 ± 0.5) pc (81.8 ± 1.7) ly |
| Period of circulation | ζ 1,2 : approx. 1100 years AB: 58.9 years |
| Angular distance | ζ 1,2 : 6 " AB: 1" |
| Individual data | |
| Apparent brightness | A: 5.6 mag |
| Spectral class | A: F7 V B: F9 V C: G0 V D: M |
| Designations and catalog entries | |
|
ζ Cancri : 16 Cancri • BD + 18 ° 1867 • HIP 40167 • Σ 1196 • ADS 6650 • WDS J08122 + 1739 |
|
ζ Cancri ( Zeta Cancri , ζ Cnc for short ) is a star system in the constellation Cancer , a little more than 80 light-years away . The star bears the historical proper name Tegmen (Latin for "covering, shell, garment", also Tegmine ).
On September 12, 2016, the IAU established the proper name Tegmine as a standardized proper name, but only for the brightest star. All other stars or components of the star system therefore have no proper name.
The system consists of at least four, probably five, stars. The components A and B are main sequence stars of the spectral class F and orbit each other with a period of around 59 years. Together they are referred to as ζ 1 Cancri for historical reasons . The component A has an apparent magnitude of 5.6 mag. Component C is a G main sequence star and component D presumably consists of two (as yet unresolved) M stars; they are also called ζ 2 Cancri . The orbit of the CD system around AB takes about 1100 years.
Since the angular distance between A and B is currently only 0.8 arc seconds (position angle: 72 degrees), a telescope with an objective diameter of 20 centimeters is required to separate them. The gap will increase by 2020, so that the resolution should then also be possible with smaller instruments. The separation of the CD system from AB is already possible with a telescope with a 5 centimeter lens opening, as the angular distance is 5.7 arc seconds (position angle: 88 degrees).
All components of ζ Cancri can be covered as ecliptic stars by the moon and (very rarely) also by planets .
The double star nature of ζ Cancri was discovered in 1756 by Tobias Mayer and his triple star nature in 1783 by William Herschel .
Web links
Individual evidence
- ↑ Bulletin of the IAU Working Group on Star Names, No. October 2, 2016. (PDF) Retrieved November 10, 2016 (English, 151 KiB).