Double Star of the Month - February 2010
In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.
STF1127 (07 47 00.43 +64 03 07.3) is a coarse, relatively bright triple star in Camelopardalis about 90 arc minutes south of 51 Cam. The magnitudes are given in the WDS as 7.0, 8.5 and 9.7 about 0.5 mag fainter in each case than the corresponding figures in Celestial Objects for Common Telescopes. Webb notes the colours as very white, ash and orange but no other observers venture a colour estimate. The primary is A2V. Component B is 5".4 away in position angle 340 degrees almost unchanged since the early 19th century whilst C is 11".7 distant from A in PA 177. Between STF1127 and 51 Cam the neat pair STF1122 can be seen.
HJ 3928 (07 05 32.05 -34 46 40.1) The companion star was discovered in 1836 on sweep 809 of John Herschel's 20-foot reflector, along with two more distant, much fainter (10.8 and 13.5 mag) and probably unrelated stars. AB is a binary star with the position angle decreasing from 157 degrees at discovery to 145 degrees now and the separation closing from 4.0 to 2.7 arc seconds in the same interval. The magnitudes are 6.47 and 7.81 according to the WDS so the pair should be well seen in 100-mm. Star A is 175 light years away according to the revised Hipparcos catalogue.
Bob Argyle - Double Star Section Director