Stargazers: Searching for the colorful stars
Beginning stargazers are often disappointed because they cannot see the glorious colors that appear in celestial photographs taken by massive telescopes. Experienced sky watchers know that this is because the human eye's color sensors do not function well under low levels of light. Anyone who has ever sat in a dark room has experienced this phenomenon.
This can be disappointing for novices who peer through a telescope to see the wonders of the heavens. Star clusters, nebulae and galaxies all appear gray, despite what some telescope manufacturers imply by printing colorful photos on the telescope packaging.
But this doesn't mean you can't see colors in the night sky. In fact, if you glance around the sky tonight, I'll bet you'll find at least one colorful star. You will most likely spot Arcturus, a brilliant orange star, high in the eastern sky after dark. Arcturus, in the constellation Bootes, is a giant orange star that is nearing the end of its stellar life.
So, why can we see the color of Arcturus, but not that of most other celestial objects? Because its light is both bright and concentrated into a point rather than being spread out like nebulae and galaxies. Aim binoculars or a small telescope in the direction of Arcturus, and you'll see its color even more prominently. This is because the optics will gather much more light than your eye and will help stimulate your color receptors.
Now, if you'd like to see an even redder star, you'll need to cast your gaze high overhead after dark this week. Here lies a star that astronomers know as Y Canum Venaticorum. Normal people just call it La Superba (the magnificent), so named by Father Angelo Secchi, the mid-19th century astronomer.
To find La Superba, you'll first need to locate the Big Dipper, which is now standing high overhead, and just above that, the two most prominent stars of Canes Venatici, the hunting dogs. About two-thirds of the way between the bend of the Dipper's handle (Mizar) and the westernmost star of Canes Venatici (Chara) lies a very faint star, one you may not be able to spot with just your eyes if you're near city lights. Don't worry, though: Binoculars or a small telescope aimed in its direction should solve this problem.
La Superba is a star about three times more massive than our sun. If brought to our solar system, it would swallow the sun and the orbits of Mercury, Venus and Earth.
What makes this star unique is that it's what astronomers call a carbon star, one of the few visible to the unaided eye. It is a giant star like Arcturus, and it is also nearing its death. However, unlike most aging stars, La Superba has accumulated more carbon compounds in its outer atmosphere. Eventually — as all similar aging stars do — La Superba will shed these outer layers into space in a series of eruptions, and will end its life as a white dwarf star.
But for now it's red — very red. If you aim binoculars or a small telescope in its direction, you'll be delighted by what you see.
Visit Dennis Mammana at www.dennismammana.com.
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