Tuesday, March 21
Well, this is a somewhat misleading title. Actually, all stars are suns and all suns stars, but I want to point out a few visible in our sky tonight that are close to being similar to our sun in size, color and temperature.
Just what kind of star is our sun? Like baby bear's porridge, it's just right. Astronomers classify it as type-G star. It falls in the lower-middle range of the enigmatic O, B, A, F, G, K and M stellar classification system. The O, B and A stars are hot and blue to blue-white; the F, G and K stars are sunlike in temperature and color; and the M stars are cool and red.
Tonight's evening sky contains five stars that are not only sunlike, but also less than 35 light-years away -- a mere stone skip across the interstellar pond astronomically speaking. One wonders: Could intelligent skywatchers be regarding our sun, which would appear to them as a 4th- or 5th-magnitude star, and wondering if intelligent life might abide around it?
Our first sunlike star (map 1) is Beta Canum Venaticorim, also known as Chara. This is the second-brightest star in the dim constellation Canes
Venatici, the Hunting Dogs, but that's not saying much. It shines only at magnitude 4.3. It is the same size as our sun but slightly younger and more luminous. Its distance is 30 light-years.
Southeast in the equally modest constellation Coma Berenices, Berenices Hair, is the 4.2-magnitude star Beta Coma Berenices. It is almost exactly the same size and luminosity of the sun. Its distance is 27 light-years.
On the opposite side of the sky (map 2), in the southwest, the yellow star Epsilon Eridani in Eridanus the River is one of our nearest sunlike neighbors, a mere 10.7 light-years distant. Epsilon is a K-type star, so it is slightly cooler and less luminous than the sun. It has been the subject of several attempts to listen for signs of intelligent radio signals, all to no avail, of course. Some astronomers believe a large planet, or perhaps a small stellar companion orbits this interesting star, but that, too, has yet to be confirmed. And, as I've mentioned in a previous "Skywatch" column, Epsilon Eridani is also the fictional sun of Mr. Spock's home planet Vulcan.
The southern quadrant of sky (map 3) harbors a more promising candidate in Chi 1 Orionis, the star marking the tip of Orion the Hunter's upheld sword. Chi is equal in size to the sun and slightly more luminous. Its distance is 32 light-years.
This is not to say that countless other stars out there tonight hotter, cooler, larger or smaller than the sun don't have terrestrial type planets with hospitable environments. But if your goal is to search for intelligent life in the universe, you probably want to begin your quest in places that are more likely to favor life as we know it. So, you begin with the all-important home star, one like the sun. And there are a LOT of sun-like stars out there.
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