The Constellation Orion Ryukyu Astronomy Club 28 March

The Constellation Orion Ryukyu Astronomy Club 28 March 2009

Discussion Topics • • Locating Orion Mythology of Orion Brightest Stars in Orion Nebula Trapezoid Star Cluster Horsehead Nebula Double stars in Orion

Locating Orion is the key to locating the constellations of the Winter Sky

Locating Orion

Mythology of Orion • In Greek mythology, Orion was a great hunter who eventually offended the gods, especially Apollo tricked Artemis, the Goddess of the hunt, into shooting Orion on a bet. When she discovered that she had shot Orion, she quickly lifted him to the heavens and made him immortal, where he now hunts eternally with his two dogs, Canis Major and Canis Minor. In front of him is his prey Taurus the Bull.

Brightest Stars of Orion And Deep Sky Objects Meisaa Betelgeuse Bellatrix Mintaka Alnilam Alnitak Horsehead Nebula Trapezium M 42 Orion Nebula Saiph Rigel

Brightest Stars of Orion • Betelgeuse: "Alpha Orionis" is a massive red supergiant star nearing the end of its life. It is the second brightest star in the Orion constellation and the twelfth brightest star in the night sky. • Rigel: "Beta Orionis" is a blue supergiant that is the seventh brightest star in the night sky. • Bellatrix: "Gamma Orionis“ is the twenty-second brightest star in the night sky. Bellatrix is considered a blue giant, though it is too small to explode in a supernova. Its luminosity is derived from its high temperature rather than its radius. Bellatrix serves as Orion's "left shoulder. • Mintaka: "Delta Orionis“ is the faintest of the three stars in Orion’s belt. It is a multiple star system composed of a large blue giant and a more massive white star. Mintaka is the westernmost of the three stars that constitute Orion's Belt. • Alnilam: "Epsilon Orionis, " is a blue supergiant, despite being nearly twice as far from the Sun as Mintake and Alnitak, the other two belt stars. • Alnitak: "Zeta Orionis" is the easternmost star in Orion's Belt. It is a triple star 800 light years distant, with the primary star being a hot blue supergiant. • Saiph: "Kappa Orionis“ serves as Orion's right foot. It is of a similar distance and size to Rigel, but appears much fainter, as its hot surface temperature (46, 000°F or 26, 000°C) causes it to emit most of its light in the ultraviolet region of the spectrum.

M 42 The Orion Nebula - Interstellar cloud of hydrogen, dust, and plasma. - ~1300 light years away - ~24 light years across - Visible to naked eye

Trapezium Star Cluster - Over 1000 young stars - Estimated 1 M years old - Most stars clouded from view by dust - Only 4 -5 stars visible with small scope

The Horsehead Nebula

Double Stars in Orion Star Magnitudes Separation Notes Rigel (beta) 0. 1, 6. 8 9. 5” Difficult because of glare from primary. Alnitak (zeta) 1. 9, 4. 0 2. 3” Test for 75 mm telescope Mintaka (delta) 2. 2, 6. 3 53” Wide separation Eta 3. 8, 4. 8 1. 5” Test for 100 mm telescope Sigma 3. 7, 10, 7. 5, 6, 8 11”, 13”, 42”, 30” Quintuple star: all components visible to small telescope Theta_1 6. 8, 7. 0, 5. 4, 6. 3 The Trapezium (see earlier slide) Iota 2. 7, 6. 9, 11 11”, 50” 747 4. 7, 5. 5 36” Lambda 3. 6, 5. 5 4. 4” Rho 4. 5, 8. 3 7” - Wide separation; same field as Iota

Orion Stars to mag 7. 0 Double stars indicated by

Finally, The Okinawan Mythology for Orion