Stars in Lyra
|
Stars in Lyra |
|
|
|
|||||||||
|
Deep Sky Object Chart
|
Alpha Lyrae (Vega) is the fifth brightest night time star, shining at magnitude 0.04 and marking one corner of the three-constellation "summer triangle". The name is derived from the Arabic "Al Nasr al Waki", or the "swooping eagle" - the Lyre was often pictured as being grasped in the talons of an eagle in medieval times. Located just 27 light years away, this star is bright in our sky mostly because it is close by; however, Vega is also brighter than most stars, and 58 times brighter than ours, so it has some legitimate claim on your attention.
Vega has achieved recent fame after it was discovered that a giant ring of dust (not visible in any telescope) circles the star; it is speculated that this may be the left-overs from the process which forms planets. If so, the scene at Vega today may look much like our solar system soon after it formed 5 billion years ago. Vega itself is very different than our sun, brighter, more massive, and shining with a much hotter blue light - but this may suggest than many kinds of suns may have worlds.
|
|||||||||
Beta Lyrae (Sheliak) is an easily located third magnitude star southeast of Vega, marking the southwest corner of the skewed rectangular pattern of Lyra. Sheliak is an example of an eclipsing binary star - twin stars which are so close together that no telescope can see them as a pair, but that betray their nature by blocking out one another's light as they circle each other. Sheliak swings between magnitudes 3.4 and 4.1 in a cycle of just 12.9 days; both of the stars involved are hot blue giant suns, several thousand times brighter than our own. Beta Lyrae can be compared in binoculars with Gamma Lyrae, 1.7 degrees to its east - Gamma is a steady magnitude 3.25; at maximum, the stars are nearly equals - at minimum, Sheliak is significantly the fainter of the two. Sheliak apparently is not just a double star, but a multiple; the two telescopic field stars at 47 and 86 arc seconds (magnitudes 7 and 9, respectively) seem to be members of this amazing star system...and the 7th magnitude companion is apparently also a double star. Sheliak is thus a quintuple, or five-star, system! Sheliak is approximately 800 light years away.
|
||||||||||
Delta Lyrae is a widely separated pair of stars four degrees southeast of Vega, marking one corner of the "lyre" asterism, and can be seen as a pair in binoculars. Seemingly split by a third the moon's width, they are in fact a few light years apart! A closer look with a telescope will reveal that these are actually just the brightest of a small cluster of stars; Delta 2 is the brightest of the bunch, and shines with an orange color - Delta 1 comes in next, and is distinctly blue. At the calculated distance of 800 light years from us, this means Delta 2 outdoes our sun by 1300 times in brightness. The scattered cluster around these stars is sometimes referred to as the Delta Lyrae Association.
|
||||||||||
Epsilon Lyrae is well known to amateur astronomers as the "double double", and is in fact just that: two pairs of two stars each, each of the close pairs separated by enough distance (3.5 arc minutes) that binoculars have no trouble showing the system as two stars. A moderate amateur telescope, however, shows that each member of the wide pair is itself a very close double, the separations being 2.8 and 2.6 arc seconds. All four members of the system are similar in brightness (magnitudes from 5.06 to 6.02) and color (all white). Added to this, one of these stars is apparently attended by an additional companion only detectable by spectroscope; thus, Epsilon Lyrae is a five star system. While the closer pairs seem almost to touch in your telescope, remember that you're looking 160 light years away; the real separations are 15 times more than from the sun to Pluto! This means the much larger distance between each pair is about a fifth of a light year. This configuration sounds weird to those of us used to just one sun, but is hardly unique in our galaxy; Nu Scorpii is another example visible in amateur instruments at this time of year. To find Epsilon Lyrae, look just 1.5 degrees northwest of brilliant Vega.
An imaginary view from a planet in the Epsilon Lyrae system.
|
||||||||||
Zeta Lyrae is an easy an attractive binary star, just southeast of Vega. The magnitudes of the two stars are 4.5 and 5.5, and are separated by a goodly 43 arc seconds - about the size of Jupiter in your telescope field. Both of the stars are white in color.
|
||||||||||
|
|
||||||||||
