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Chesmayne · 10-09-2008, 03:37 AM

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Draco constellation description for the ground crew.......

The Dragon. He wends his way between Ursa Major and Ursa Minor. During the time of the Egyptian pharaoh Khufu ‘Thuban’ [one of the stars in the Dragon] was near our N. Pole. The burial chamber at Gizeh was aligned with Thuban. Draco is a faint constellation near the north celestial pole bordering Ursa Minor. It is the 8th largest constellation in our sky - of the 88. The small asterism of four stars marking the head of the dragon is the best known section of this group. Many double stars and galaxies are to be found here. In Greek mythology, one of the labours of Hercules was to steal golden apples from the garden of the Hesperides. A dragon protected the garden, and was slain by Hercules. 1082.95° square (2.63% of the sky). The north ecliptic pole is to be found here. In Greek mythology the dragon is Ladon, the guardian of the ‘golden apples’ of immortality which grew in the garden of Hesperides, beyond the River of Time, in the land of death. It is Ladon which Hercules kills in his 11th labour to obtain the golden apples.

Nu Draconis is an easy double [blue-white] star for binocular viewers conveniently positioned as one of the dragons teeth. Nu is separated by 62s or, 2,300 AU and lies at a distance of 120 ly at +4.7 - binary star. It is also known by the traditional name Kuma. Nu is a very nice binocular double. It is one of the objects on many binocular observing programs. The components of Nu Dra point in an EW direction and are of similar brightness. PA is 312°. This pair of stars are superb in binoculars and appear as two blue white beacons shining in the sky. Easily split even with a 6 x 30mm finderscope. The western one of the pair is Nu-1 [+4.87], the eastern one Nu-2 [+4.89]. Nu-2 itself is double - a low-mass companion circles it every 38.6 days. Nu-1 and Nu-2 are separated by at least 1900 AU and take 44,000 years to make a full circuit.

Messier 102. It is the only Messier object in Draco. It is sometimes referred to as the ‘Spindle Galaxy’ [NGC-5866]. It is +10, lenticular, type S0_3 and appears as an elongated pencil line in a telescope measuring 5m x 2m. M102 is one of the lost [but recovered] Messier objects! NGC-5866 is accepted by most observers as being M102. It may be glimpsed in a finder scope. Seen from nearly edge on, the dark dust lane shows up nicely cutting through the center. The ‘Spindle Galaxy’ is located at 15h 06m 39s RA and +55° 43m 58s dec. It has an apparent angular size of 5.2m x 2.3m and a visual brightness of +9.9. Estimated mass is one trillion solar masses. The distance is estimated to be about 32 million lys and approximately 60,000 ly in diameter. It is the brightest of a group of galaxies containing 5907, 5879, and several fainter galaxies - 5866A, 5866B, 5862, 5905, 5908, and IC 1099. There is another spindle galaxy in Sextans.

The ‘Cat Eye’ nebula is a magnificent planetary nebula. NGC-6543 will need high magnification and is 18s across. Intricate structures including concentric gas shells, jets of high-speed gas and unusual shock-induced knots of gas can be seen in this object. It is only about a millennium old and is a visual fossil record of the dynamics and late evolution of a dying star in ‘real time’. 6543 is suspected of being a double star system. The effects of two stars orbiting one another explains its structure.

T-Draconis [a Mira-type variable star] has a 422 day period. To keep track of its slow rise in brightness some astronomers observe it once a week.

The head of the Dragon [Draco] is a distinctive asterism of four stars that can be seen quite easily in binoculars. These are Beta, Gamma, Xi and Nu.

Eltanin [Gamma] was first mentioned by Ulugh Beg [Uzbeg] in the 15th century. He referred to it as ‘Ras al Tinnin’ [the head of the dragon], which is a K5 giant and has an orange tint - the right eye in the Dragon. It is the brightest star in Draco. Its name (also written as Etamin) comes from the Arabic for ‘the serpent’ and stands for the whole constellation. Eltanin’s high northerly position takes it nearly through the zenith causing it to be known formerly as the ‘zenith star’. While attempting to measure its parallax - the annual shift in stellar position caused by the changing position of the orbiting Earth (from which we get stellar distance) James Bradley, in 1728, discovered the ‘aberration of starlight’, which is caused by the velocity of the moving Earth relative to the speed of the light coming from the star. This discovery proved, once and for all, that Copernicus was right and that Earth truly does move around the Sun. Eltanin is moving toward us, and will make a closest pass of 28 lys about 1.5 million years from now when it will be the brightest star in the sky and rival Sirius. Physically, Eltanin is an orange giant K star, about half the size of Mercury’s orbit. It was the pole star about 3500 BC.

Another star of note in Draco is Rastaban at +2.79, G2, 360 ly distant with a radius 40 times solar. Stars like Rastaban are often in rapid states of evolutionary transition - there are not many of these in the sky at any one time. It has a companion at 450 AU that takes 4,500 years to complete a revolution. Its destiny is to become a white dwarf. Grumium, K2, a yellow star in the Jaw of the Dragon. In the Arabic theme of this constellation the stars beta (Alwaid), gamma (Etamin), nu (Kuma) and xi (this star Grumium) in the Head of the Dragon represent four mother camels protecting a baby camel from the attack of two hyenas! The star Grumium (scientific name Xi Draconis) is located at RA 17h 53.528m and dec 56° 52.367m. Grumium is a dim star, +3.75, K2-III. It has an Hd number of 163588, an FK5 number of 671, and a SAO number of 30631 - so, now you know.

Alpha Draconis is also known as Thuban. In 2,800 BC Thuban was the star nearest the celestial north pole. Today Polaris is nearly 1° away from our north pole. Alpha is not the brightest star in this constellation at +3.7. Its importance is highlighted in that it is the Alpha star of Draco (the Dragon) even though it not close to being the brightest [Beta is +2.8, Gamma the brightest at +2.2, and Delta at +3.1]. It was almost exactly at the pole in 2700 BC. Thuban is among a rare class of hot giant stars, its temperature of 9800 Kelvin near that of Vega. It is over five times as luminous as Vega (and 300 times more luminous than our Sun), its +4 status the result of its distance of 310 lys. It has a faint unseen companion in orbit with a 51 day period.

Psi Draconis. Double. Primary +4.9 [yellowish], secondary +6, 30s distant, bluish tint.

NGC-5985. Tightly wound spiral arms visible in a telescope.

NGC-5905 and NGC-5908. 5905 is a barred spiral, 4m x 3m. 5908 is a regular spiral, 3m x 1m. Both are +12.

NGC-5907. +10. One of the finest edge-on spirals. 12m [quite large] by 1m wide. All of its light is concentrated into a thin line and a dust lane is visible in larger telescopes. Easy in an 8-inch.

NGC-4236. +9.7. 18m x 7m [large], barred spiral. A large telescope will detect detail in the system.

NGC-6503, 6643. 6503 is +10, 6m x 2m. 6643, +11.

NGC-6543. Planetary nebula. +8.8. Use high magnification. 18s in size. 1,700 ly distant.

10-09-2008, 03:37 AM	#19
Chesmayne Avalon Senior Member Join Date: Sep 2008 Location: Dublin, Ireland Posts: 24	Draco constellation....... http://www.chesmayne.info Draco constellation description for the ground crew....... The Dragon. He wends his way between Ursa Major and Ursa Minor. During the time of the Egyptian pharaoh Khufu ‘Thuban’ [one of the stars in the Dragon] was near our N. Pole. The burial chamber at Gizeh was aligned with Thuban. Draco is a faint constellation near the north celestial pole bordering Ursa Minor. It is the 8th largest constellation in our sky - of the 88. The small asterism of four stars marking the head of the dragon is the best known section of this group. Many double stars and galaxies are to be found here. In Greek mythology, one of the labours of Hercules was to steal golden apples from the garden of the Hesperides. A dragon protected the garden, and was slain by Hercules. 1082.95° square (2.63% of the sky). The north ecliptic pole is to be found here. In Greek mythology the dragon is Ladon, the guardian of the ‘golden apples’ of immortality which grew in the garden of Hesperides, beyond the River of Time, in the land of death. It is Ladon which Hercules kills in his 11th labour to obtain the golden apples. Nu Draconis is an easy double [blue-white] star for binocular viewers conveniently positioned as one of the dragons teeth. Nu is separated by 62s or, 2,300 AU and lies at a distance of 120 ly at +4.7 - binary star. It is also known by the traditional name Kuma. Nu is a very nice binocular double. It is one of the objects on many binocular observing programs. The components of Nu Dra point in an EW direction and are of similar brightness. PA is 312°. This pair of stars are superb in binoculars and appear as two blue white beacons shining in the sky. Easily split even with a 6 x 30mm finderscope. The western one of the pair is Nu-1 [+4.87], the eastern one Nu-2 [+4.89]. Nu-2 itself is double - a low-mass companion circles it every 38.6 days. Nu-1 and Nu-2 are separated by at least 1900 AU and take 44,000 years to make a full circuit. Messier 102. It is the only Messier object in Draco. It is sometimes referred to as the ‘Spindle Galaxy’ [NGC-5866]. It is +10, lenticular, type S0_3 and appears as an elongated pencil line in a telescope measuring 5m x 2m. M102 is one of the lost [but recovered] Messier objects! NGC-5866 is accepted by most observers as being M102. It may be glimpsed in a finder scope. Seen from nearly edge on, the dark dust lane shows up nicely cutting through the center. The ‘Spindle Galaxy’ is located at 15h 06m 39s RA and +55° 43m 58s dec. It has an apparent angular size of 5.2m x 2.3m and a visual brightness of +9.9. Estimated mass is one trillion solar masses. The distance is estimated to be about 32 million lys and approximately 60,000 ly in diameter. It is the brightest of a group of galaxies containing 5907, 5879, and several fainter galaxies - 5866A, 5866B, 5862, 5905, 5908, and IC 1099. There is another spindle galaxy in Sextans. The ‘Cat Eye’ nebula is a magnificent planetary nebula. NGC-6543 will need high magnification and is 18s across. Intricate structures including concentric gas shells, jets of high-speed gas and unusual shock-induced knots of gas can be seen in this object. It is only about a millennium old and is a visual fossil record of the dynamics and late evolution of a dying star in ‘real time’. 6543 is suspected of being a double star system. The effects of two stars orbiting one another explains its structure. T-Draconis [a Mira-type variable star] has a 422 day period. To keep track of its slow rise in brightness some astronomers observe it once a week. The head of the Dragon [Draco] is a distinctive asterism of four stars that can be seen quite easily in binoculars. These are Beta, Gamma, Xi and Nu. Eltanin [Gamma] was first mentioned by Ulugh Beg [Uzbeg] in the 15th century. He referred to it as ‘Ras al Tinnin’ [the head of the dragon], which is a K5 giant and has an orange tint - the right eye in the Dragon. It is the brightest star in Draco. Its name (also written as Etamin) comes from the Arabic for ‘the serpent’ and stands for the whole constellation. Eltanin’s high northerly position takes it nearly through the zenith causing it to be known formerly as the ‘zenith star’. While attempting to measure its parallax - the annual shift in stellar position caused by the changing position of the orbiting Earth (from which we get stellar distance) James Bradley, in 1728, discovered the ‘aberration of starlight’, which is caused by the velocity of the moving Earth relative to the speed of the light coming from the star. This discovery proved, once and for all, that Copernicus was right and that Earth truly does move around the Sun. Eltanin is moving toward us, and will make a closest pass of 28 lys about 1.5 million years from now when it will be the brightest star in the sky and rival Sirius. Physically, Eltanin is an orange giant K star, about half the size of Mercury’s orbit. It was the pole star about 3500 BC. Another star of note in Draco is Rastaban at +2.79, G2, 360 ly distant with a radius 40 times solar. Stars like Rastaban are often in rapid states of evolutionary transition - there are not many of these in the sky at any one time. It has a companion at 450 AU that takes 4,500 years to complete a revolution. Its destiny is to become a white dwarf. Grumium, K2, a yellow star in the Jaw of the Dragon. In the Arabic theme of this constellation the stars beta (Alwaid), gamma (Etamin), nu (Kuma) and xi (this star Grumium) in the Head of the Dragon represent four mother camels protecting a baby camel from the attack of two hyenas! The star Grumium (scientific name Xi Draconis) is located at RA 17h 53.528m and dec 56° 52.367m. Grumium is a dim star, +3.75, K2-III. It has an Hd number of 163588, an FK5 number of 671, and a SAO number of 30631 - so, now you know. Alpha Draconis is also known as Thuban. In 2,800 BC Thuban was the star nearest the celestial north pole. Today Polaris is nearly 1° away from our north pole. Alpha is not the brightest star in this constellation at +3.7. Its importance is highlighted in that it is the Alpha star of Draco (the Dragon) even though it not close to being the brightest [Beta is +2.8, Gamma the brightest at +2.2, and Delta at +3.1]. It was almost exactly at the pole in 2700 BC. Thuban is among a rare class of hot giant stars, its temperature of 9800 Kelvin near that of Vega. It is over five times as luminous as Vega (and 300 times more luminous than our Sun), its +4 status the result of its distance of 310 lys. It has a faint unseen companion in orbit with a 51 day period. Psi Draconis. Double. Primary +4.9 [yellowish], secondary +6, 30s distant, bluish tint. NGC-5985. Tightly wound spiral arms visible in a telescope. NGC-5905 and NGC-5908. 5905 is a barred spiral, 4m x 3m. 5908 is a regular spiral, 3m x 1m. Both are +12. NGC-5907. +10. One of the finest edge-on spirals. 12m [quite large] by 1m wide. All of its light is concentrated into a thin line and a dust lane is visible in larger telescopes. Easy in an 8-inch. NGC-4236. +9.7. 18m x 7m [large], barred spiral. A large telescope will detect detail in the system. NGC-6503, 6643. 6503 is +10, 6m x 2m. 6643, +11. NGC-6543. Planetary nebula. +8.8. Use high magnification. 18s in size. 1,700 ly distant. Last edited by Chesmayne; 10-09-2008 at 01:38 PM.