SJAA Ephemeris April 2002 | SJAA Home | Contents | Previous | Next

The Red, White, and Blue Star

Bob Brauer


As Orion slips into the western evening sky, you can find a rather patriotic sight: Iota Orionis. This multiple star system displays an impressive amount of color with red, white, and blue components.

Start with Orion's belt and star-hop your way south down the Hunter's sword. (Make sure you pause to view the great Orion Nebula), then continue south to the brightest "star" at the south end of the sword, bright third magnitude (2.77) Na'ir al Saif, Arabic for "the Bright One in the Sword."

This star is a brilliant, white, O class star estimated to be roughly 15 solar masses. A close companion, 11 arcseconds distant, is a bluish 7th magnitude B class star. The third component visible in small telescopes is 50 arcseconds away from Iota Orionis, an 11th magnitude class A or F dwarf. A very close companion has been detected spectroscopically with an orbital period of 29 days and is the subject of current research projects on strong solar winds which collide producing powerful X-rays.

The three components we see visually are described in Burnham's as "white, pale blue, and grape red." I need a 6-inch or larger telescope to see color in the dim red dwarf, but it is clearly seen with an 8-inch.


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