General Information
The Helix Nebula is an example of a planetary nebula, or 'planetary' formed at the end of a star's evolution. Gases from the star in the surrounding space appear, from our vantage point, as if we are looking down a helix structure. The remnant central stellar core, known as a planetary nebula nucleus or PNN, is destined to become a white dwarf star. The observed glow of the central star is so energetic that it causes the previously expelled gases to brightly fluoresce.
The Helix Nebula in the constellation of Aquarius lies about 700 light-years away, spanning about 0.8 parsec or 2.5 light-years. Recent images by the Hubble Space Telescope of the Helix Nebula are a composite of newly released images from the ACS instrument and the wide-angle images from the Mosaic Camera on the WIYN 0.9-metre telescope at Kitt Peak National Observatory.
Currently, the age is estimated to be 10,600+2,300
−1,200 years, based solely upon a measured expansion rate of 31 km·s−1.
Read more about this topic: Helix Nebula
Famous quotes containing the words general and/or information:
“Hence that general is skilful in attack whose opponent does not know what to defend; and he is skilful in defense whose opponent does not know what to attack.”
—Sun Tzu (6th–5th century B.C.)
“We hear a great deal of lamentation these days about writers having all taken themselves to the colleges and universities where they live decorously instead of going out and getting firsthand information about life. The fact is that anybody who has survived his childhood has enough information about life to last him the rest of his days.”
—Flannery O’Connor (1925–1964)