Wasat (Delta Geminorum) -- Triple Star System in Gemini
Wasat is a 3.5 magnitude star in Gemini. In Arabic it translates to “Middle”, which is
appropriate since it is somewhat in the center of the constellation. Wasat is easily
visible from my suburban back yard.
Often, I will begin my observing period with a double star as I wait for my telescope’s
temperature to equalize to the outside air. For my 155mm refractor I usually give it a
half hour or so depending on the temperature difference between where I store the
telescope (indoors) to the deck of the house. I generally pick a double star that is
easy to find and use it to test if tube currents are still present inside the refractor. A
single star would work for testing, but I like the esthetics of a double star. Once no
tube currents are detected and I feel that the telescope has equalized, I switch to the
celestial targets of choice for that night.
On March 4, 2018, Wasat was my choice. The primary is a stunning yellow-white star
while the secondary is (to me) a subdued bluish-purple. They make a nicely
contrasting pair. The primary star is a spectroscopic binary but these two stars are
not separable in my telescope (or any telescope that I am aware of). So Wasat is
really a three-star system. Although, only a double-star in my telescope it is a
pleasant view and my first drawing for the night.