Looking for sun-like stars
GATEHOUSE NEWS SERVICE
A couple columns ago we talked about the sun, a typical Class G2 star.
Stars have a wide range of characteristics. Astronomers give stars ratings based on their mass, temperature and luminosity. Obviously the sun is the kind of star suitable for life as we know it. While the question remains hypothetical if there are other worlds out there like Earth, a good place to look may be around other stars reasonably similar to our own.
There’s a whole list of them and some are not so far away. Epsilon Eridani, for example, has a mass that is 8/10ths of our sun. Epsilon Eridani is situated only 10.5 lights years away, in the constellation Eridanus the River. “Only” 10.5 light years is something you’d expect from an astronomer. This distance equates to 60.9 TRILLION miles. No one in Washington (hopefully) has even dreamed of a number that big, in terms of dollars. Only astronomers think bigger than that, but in the sense of vastness of space. Compared to our galaxy or the observable universe, 10.5 light years is right next door. If we managed to make a spacecraft that went even half the speed of light (we‘re no where close to being able to do that), we might reach this star in 21 years. Anyone want to be a good neighbor and launch a “welcome wagon” from Earth?
Does Epsilon Eridani harbor any Earth-like worlds? None have been found, but huge advances in search techniques have taken place at our observatories since the first exo-planet was confirmed in 1995, around another star, 51 Pegasi. At first only immense planets, larger than Jupiter have been indirectly inferred; improvements in the search and dedication on the part of researchers have since found planets only a few times bigger than Earth. The race is on for a world similar to ours.
There are active searches by some astronomical teams who aim radio telescopes toward stars, in the event someone or something out there is broadcasting in our direction. It is one of the few pursuits of science where we have no idea that the subject matter even exists.
If any one living on a planet orbiting Epsilon Eridani has been beaming messages or their version of re-runs of “I Love Lucy” our way, so far we haven’t picked it up. This star has been under intense scrutiny of alien searches by the SETI (Search for Extraterrestrial Intelligence) programs, and was the target of the very first one, known as Ozma, which was under way in 1960.
Epsilon Eridani has since been found to be surrounded by a ring of dust and does have at least three planets believed to have formed from that dust. This star is easily found without optical aid under a reasonably dark sky. At magnitude 3.7, the star and its constellation are in view on winter evenings.
There are many other sun-like stars relatively near. Another reason for investigating these, besides pondering habitable worlds – whether an abode of present life or desirable destinations for future Earth travelers – are down-home needs to better understand our own sun. Why do sunspot cycles change over long periods? What affect does changes in our home star have on Earth climate and our own habitability? Comparison with other stars is a reasonable way to further our knowledge of what we can expect from our favorite star.
On June 5 and 6, look for the bright-red planet Mars about halfway up in the western sky shortly after dark. Mars will be less than 1 degree from the bright, bluish-white star Regulus, which is on the left. You won’t need any optical aid, but binoculars will provide an even more impressive view.
Much lower, to the right, is the brilliant planet Venus.
The moon this week is a crescent in the east before dawn; it reaches new phase on June 12. After that, the crescent reappears in the evening west.
Keep looking up!