Lyra (“the Lyre”) is one of the smaller constellations, taking up an area of just 286 sq/deg of the northern sky between latitudes +90 and -40 degrees. It does, however, contains the 5th brightest star in the sky, Vega, which also forms part of the famous asterism of stars known as the Summer Triangle. Amongst the other many spectacular astronomical objects contained within Lyra is the beautiful Ring Nebula, as well as nine stars with confirmed planets. Lyra is the 52nd biggest of the 88 recognized constellations, and is visible in the northern hemisphere from April to December, and in the southern hemisphere in winter.
Hercules Family of Constellations
Lyra is part of the Hercules Family of constellations, which contains 19 members, including Hercules, Sagitta, Aquila, Lyra, Cygnus, Vulpecula, Hydra, Sextans, Crater, Corvus, Ophiuchus, Serpens, Scutum, Centaurus, Lupus, Corona Australis, Ara, Triangulum Australe, and Crux.
Lyra is taken to represent the lyre of Orpheus, a legendary Greek musician who was given the instrument by Apollo, and taught its use by the Muses. According to classical mythology, Orpheus was the greatest of all musicians, and was said to have been able to charm even stones with his music. His many great adventures included trying to retrieve his wife Eurydice from the Underworld, but in the end he was killed by the Bacchantes, who then cast his lyre into a river. Zeus however, sent an eagle to recover the lyre, and placed both the Lyre and the eagle among the stars.
– Vega (Alpha Lyrae) is the night sky’s fifth most luminous star (0.03 mag), and the second most luminous in the northern celestial hemisphere behind Arcturus (-0.04). It is a white dwarf (A0V) found 25 light-years away that has just over twice our sun’s mass, and 54 times its luminosity. This 455 million year old star is also a very fast spinner, with an equatorial rotational velocity of 274 km/s, which amounts to 86% of the velocity required to make it fly apart under its own centrifugal force. Around 12,000 BC, Vega was the Pole Star, which it will be again in about 13,727 years due to precession. The name Vega derives from the Arabic for “swooping eagle” or “vulture.”
– Sulafat (Gamma Lyrae), the second brightest star in Lyra, is a blue-white giant (B9 III) located around 620 light years (3.261 mag) from our solar system with a visual magnitude of 3.261. It is about 15 times bigger than our sun, twice as hot, and has a relatively fast rotational velocity of 72 km/s.
– Sheliak (Beta Lyrae), the constellation’s third brightest star, is a binary star system found 960 light years distant. It has a visual magnitude of 3.52, although being a variable star this can range from between 3.4 and 4.3 as the system’s two stars orbit and periodically eclipse one another over a 12.9414 day period. The binary system’s primary component is a blue-white giant (B7II) that is 30 times bigger than the Sun, 13 times more massive, and around 25,000 times more luminous.
Other stars of interest in Lyra includes the white subgiant Alathfar; the yellow dwarf Gliese 758; the red giant R Lyrae; the red dwarf Kuiper 90; and the orange giants Kappa Lyrae and Lambda Lyrae.
Notable Deep Sky Objects
The constellation of Lyra contains several notable deep sky objects, including two Messier Objects.
– The Ring Nebula (M57, NGC 6720) is a perennial favourite among amateur stargazers, since it is one of very few deep space objects that shows a hint of its true colour in good optics. Located about 2,300 light years away, the Ring Nebula has an apparent visual magnitude of 8.8, and is expanding at the rate of about 1 second of arc per 100 years. It is a member of a class of nebulae known as bi-polar nebulae, because of the thick ring of material around their equator that greatly extends the structure through its main symmetrical axis. Look for M57 just south of the star Vega.
– Messier 56 (M56, NGC 6779) is a globular cluster located 32,900 light years distant, and stretching across 84 light years of space. Lying between the stars Sulafat and Albireo in Cygnus, it has an apparent magnitude of 8.3, and is an easy binocular target, although you will need at least an 8-inch telescope and good seeing conditions to resolve its stars, of which about a dozen or so are variables.
– Bird’s Head Galaxy (NGC 6745) is a striking example of an interaction between three galaxies that have been colliding for hundreds of millions of years. NGC 6745 is located about 205 million light years away, shines with an apparent visual magnitude of 13.3, and is believed to be around 10 billion years old.
Three meteor showers are associated with Lyra, namely the Alpha Lyrids, the June Lyrids, and the Lyrids.
– The Lyrids, although not among the most spectacular meteor showers, does nevertheless have some things going for it, including being the longest known shower, with sightings of it dating back more than 2,600 years. The shower runs from April 16th to April 26th, with the maximum occurring on April 21st/22nd when about 10 meteors per hour can be viewed, and occasionally more than 100 meteors.
– The June Lyrids usually runs from June 10th to June 21st, but only peaks at about 8 or so blue and white meteors per hour. The upside is that more than 30% of meteors leave fire and smoke trails, which makes this one of the more photogenic showers.
– The Alpha Lyrids runs from July 9th to 20th, but is not a naked-eye shower. In fact, the best that can be expected is about one or two naked eye observations per hour, but binoculars can reveal as many as 18-33 meteors per hour at the peak that falls on July 14th.