Iota Cassiopeiae -- Multiple Star System in Cassiopeia
Three Stars & Massive Sunspots
There is no argument among observers that Iota Cassiopeiae is one of the finest triplet stars
for amateur telescopes. With high power, even the smallest of telescopes can separate the
yellow primary from the two smaller (bluish in my eyes) component stars.
The Iota Cassiopeiae star system is more complex than as viewed through a small telescope.
Both Iota A (the primary star) and Iota C have unseen smaller companion stars making it a
The primary star has patchy surface-concentrations of Iron and Chromium that help form
massive sunspots that causes variation in the brightness of the star as it rotates. The
rotational period of the yellow-colored star is less than 2 days and it fluctuates around 0.08
of a magnitude during each rotation. Variable stars of this type are lumped together as
Alpha-2 Canum Venaticorum stars. The addition of the “pSr” in the star’s spectral type is due
to its unusually strong lines of strontium and calcium. See Kanipe & Webb’s “Annals of the
Deep Sky volume 4” for additional details on this interesting star.
Tonight, the moon is nearly full and flooding the sky with light. Most deep-sky objects are
compromised when the moon so dominates the sky, but not the brighter double/multiple stars
systems. It was a perfect night to view Iota Cassiopeiae. Seeing the attractive triplet while
trying to wrap my brain around a distant sun covered with massive sunspots, made my
awareness of the bright moon slowly disappear.