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Sigma Ori lies about
a degree to the southwest of Alnitak, the easternmost star in the "belt"
or Orion. This system of five stars puts on a great show in telescopes
both large and small.
The closest pair (AB)
consists of two gravitationally bound stars, the 3.8 magnitude Sigma Ori
itself, and it's 5.3 magnitude close companion. Currently a mere 0.24"
apart, these stars take 170 years to complete one orbit about one-another.
A larger aperture instrument, excellent seeing, and high magnification
are required to see this pair.
The 10th magnitude star C
lies 11" to the SW. To the NE lies the 6.9 magnitude star D (13" away). Farther to the NE, at a distance of 42", lies the 6.5 magnitude star E.
This star is the variable star V1030 Ori, an SX Ari type variable with
a range of ~0.15 magnitude overperiod of 1.2 days.
A full orbit of the AB
pair.
The view in a 6-inch showing the best possible resolution. |
