Draco: The Dragon with the “Puffy Tale”

May 26th, 2009

Draco is a long, glittering chain of faint stars that curls around between Ursa Major-the “Big Dipper” and Polaris-the “North Star“ on the east side.

It was one of the original 48 constellations charted by Ptolemy and was later adopted as one of the 88 modern constellations by the International Astronomical Union. This sprawling constellation covers 1083 square degrees of sky, yet only possesses 3 bright stars. The asterism of the “Dragon” is made of up 14 main stars and 75 Bayer/Flamsteed stellar designations reside within Draco’s confines. It is bordered by the constellations of Boötes Hercules, Lyra, Cygnus, Cepheus, Ursa Minor, Camelopardalis and Ursa Major. Draco is easily visible to viewers at latitudes between +90° and +15° and is best seen at culmination during the month of July.

There are three annual meteor showers associated with Draco - starting with the Delta Draconids. Each year between March 28 and April 7, the Earth begins to pass into the meteoroid stream, and bright streaks will seem to emanate from the sky at a point near the Cepheus border. This meteor shower activity peaks on or near the date of April 7 and the fall rate averages about 5 per hour at maximum. These are known to be very slow meteors. One June 20th, the Delta Draconid meteor shower peaks. These are the offspring of Comet Pons-Winnecke. This time the radiant is more near the handle of the Big Dipper and the fall rate can be anywhere from 10 to 100 meteors per hour on the average. October 9 marks the peak of the annual Draconid meteor shower, the progeny of Comet Giacobinni-Zinner. At times, when this comet has passed near Earth, the fall rate can be spectacular with rates up to 1000 per hour! Its radiant is near Hercules and it is not uncommon even during an “off” year to spot up to 200 meteors per hour during a dark night.

Alpha-”a” Draconis-the binoculars and brightest star name is Thuban and this 300 light year distant star has played an important role in our history. At one time, Thuban was a north pole star. Due to the precession of the equinoxes, it moved on… But by 10000 AD, Thuban will gradually move back toward the north celestial pole. In 20346 AD, it will again be the pole star. Of itself, Thuban is a binary star, much too close to be split. It is also a white giant star, more than 250 times more powerful than our Sun.

Beta Draconis-”B” name is Rastaban, which literally means “head of the serpent”. Rastaban is a G-type supergiant star, and it is also a binary star. It is located about 360 light years from our solar system and if you use a telescope you just might be about to spot the 11.5 magnitude dwarf star companion to this disparate double star!

On the other hand the Gamma Draconis-“Y” name is Eltanin, which pretty much means dragon, or serpent. Despite its Bayer designation of “gamma,” it is actually the brightest star in Draco, outshining Rastaban by nearly half a stellar magnitude. Right now Eltanin is 148 light years away from us, but the orange giant star won’t stay there long. In 1.5 million years, Eltanin will pass within 28 light years of Earth and will become the brightest star in the night sky.
Off to Psi 1 Draconis - it’s the designation that looks like a pitchfork with a 1 beside it. Here we have a great double star! Its traditional name Dziban and the primary of this pair has a nice, slight yellow coloration befitting of it’s F-spectral class and it can easily be split with binoculars. Omicron-“O” supergiant star that also has a gravitationally bound companion that can be picked off with small optics.

This entry was posted on Tuesday, May 26th, 2009 at 3:16 am and is filed under Science, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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