Multiple star systems in Orion
At a combined magnitude of 3.8, Sigma Orionis can be seen with the naked eye as the star just below the eastern-most star in Orion's belt. Viewed through a telescope at medium power, it shows 4 separate stars, as seen in this image. With a large telescope and excellent seeing conditions, it might be possible to split the brightest of the group into a very close double (Sigma A and B), only about .2 arcseconds apart. Usually they appear as a single star, as they do in this image.
All 5 of these stars are larger and much more luminous than our Sun. This complex star system includes other stars, including a close companion to the A star that can only be detected spectroscopically.
The triple star Struve 761 is to the upper right of the Sigma Orionis group.
| Magnitudes | 4.0, 5.3, 8.8, 6.6, 6.3 |
| Separation from A | 0.2", 11.6", 12.9", 42" |
| Distance (light yrs) | 1270 |
| Right Ascension | 5:38.7 |
| Declination | -2 36 |
| Field of View | 18' x 13' |
Image details: A series of 1-second exposures through clear, red, green, and blue filters, taken with an SBIG STF-8300M imager through a Meade 14” LX850 telescope at f/6.
March 2019