- Zeta Cancri
Starbox short
name=ζ Cancri A/B/C
epoch=J2000.0
constell=Cancer
ra=08h12m12.7s
dec=+17°38′52″
spectral=F7V+F9V+G0V
appmag_v=+5.58/+5.99/+6.12
dist_ly=83.4 ± 2.9
dist_pc=25.6 ± 0.9
names=Tegmen, Tegmine, 16 Cancri, HR 3208/3209/3210, HD 68257/68255/68256, BD+18°1867, HIP 40167, SAO 97645/97646, GC 11142/11141, ADS 6650, CCDM J08123+1738Zeta Cancri (ζ Cnc / ζ Cancri) is a
star system in theconstellation Cancer containing at least four stars. It also has the traditional name Tegmine, Tegmen, or Tegmeni. The star system is approximately 83.4light year s fromEarth , and has a combinedapparent magnitude of +4.67.Since ζ Cancri is near the
ecliptic , it can be occulted by theMoon and very rarely byplanet s.The ζ Cancri system contains two binary pairs, ζ¹ Cancri and ζ² Cancri, which are 5.06
arcsecond s apart. These two binary stars orbit around their common centre of mass once every 1100 years.ζ Cancri can be resolved as a double star in small telescopes. The double nature of ζ Cancri was discovered in
1756 byJohann Tobias Mayer . Its was discovered to be a triple star in1781 byWilliam Herschel when he resolved the two components that make up ζ¹ Cancri. As early as1831 ,John Herschel noticed perturbations in ζ² Cancri's orbit around ζ¹ Cancri. This ledOtto Wilhelm von Struve , in1871 , to postulate a fourth, unseen, component which orbited closely the visible member of ζ² Cancri.cite journal | author=Griffin, R.F. | title=Spectroscopic Binary Orbits from Photoelectrical Radial Velocities: Paper 150: ζ Cancri C | journal=The Observatory | year=2000 | volume=120 | pages=1–47 | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000Obs...120....1G&db_key=AST&data_type=HTML&format=&high=44595cfd5a08794 ] Recent observations have resolved this fourth component and have indicated that there may be one or two more unobserved components. [cite journal | author=Hutchings, J. B., Griffin, R. F.; Menard, F. | title=Direct observation of the fourth star in the Zeta Cancri system | journal=Publ. Astron. Soc. Pac. | year=2000 | volume=112 | pages=833–836 | url=http://arxiv.org/abs/astro-ph/0004284 | doi=10.1086/316587 | format=abstract ] [cite journal | author=Richichi, A. | title=An Investigation of the multiple star Zet Cnc by a lunar occultation | journal=Astron. Astroph. | year=2000 | volume=364 | pages=225–231 | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000A%26A...364..225R&db_key=AST&data_type=HTML&format=&high=445952a4c330915 ]The components of ζ¹ Cancri are denoted ζ Cancri A and ζ Cancri B. They are both yellow-white main sequence dwarfs of spectral class F. The
apparent magnitude the two stars are +5.58 and +5.99, respectively. The two stars are separated,as of 2005 , by 0.8arcsecond s, requiring a large telescope to resolve them, but this separation will increase until the year2020 . They complete one orbit every 59.3 years.The components of ζ² Cancri are denoted ζ Cancri C and ζ Cancri D. ζ Cancri C is the brighter of the pair, having an apparent magnitude of +6.12. It appears to be a yellow G-type star, often reported as G5V, but now thought to be earlier, probably G0V. The tenth magnitude ζ Cancri D has the color of a
red dwarf , and may in fact be a close pair of two red dwarves. The separation between C and D is approximately 0.3arcsecond s, and their orbital period is 17 years.Identification
Considerable confusion has developed concerning the catalogue identities of the three bright stars. Correct correspondences were worked out by Griffin:
References
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