This was a great triple star. The central diffraction discs of the A and B components appeared to just touch at a position angle of about 68 degrees, which works out to a separation of about .9 arc seconds. These 2 stars were pale yellow in color and seemed so close in magnitude that I couldn’t tell which was the primary (which meant a PA of either 68 or 248 degrees until I researched the correct designation of primary). The third star appeared fainter, paler yellow, and at a position angle of 75 degrees. It was separated from the B star by about 4 diffraction ring radii, which works out to a separation from the A star of about 6 arc seconds. Actual values can be seen in the table below.
It appears that the A and B stars have a fairly fast orbital period with a PA of 152.7 degrees in 1991, 110.9Â° in 1998, and my estimate of 68 degrees in 2006
|Subject||Zeta Cancri (STF 1196)|
|Position (J2000)||[RA: 08:12:12.7 / Dec: +17:38:52]*|
|Position Angle*||AB=152.7Â° (1991)
|Magnitudes*||A=5.3; B=6.2; C=5.9|
|Spectral Types*||A=F8V; B=F9V; C=G5V|
|Date/Time||OCT 22, 2006 – 3:40 AM MST (OCT 22, 2006 – 10:40 UT)|
|Observing Loc.||Cinder Hills Overlook, Sunset Crater National Monument, AZ|
|Instrument||Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)|
|Eyepieces/Mag.||10 mm + 2X Barlow (240X)|
|Transparency||NELM Mag 6.8+|
|References||The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996), Tycho Double Star Catalogue (TDSC) (Fabricius+ 2002), Double stars measurements (Alzner 1998), and Spectrophotometric Catalogue of Stars (Kharitonov+, 1988) via VizieR|
*Based on published data.