Astronomy Picture of the Day 2-20-03

Explanation: A cold wind blows from the central star of the Boomerang Nebula. Seen here in a detailed false-color image recorded in 1998 by the Hubble Space Telescope, the nebula lies about 5,000 light-years away towards the grand southern constellation of Centaurus. The symmetric cloud appears to have been created by a high-speed wind of gas and dust blowing from an aging central star at speeds of nearly 600,000 kilometers per hour. This rapid expansion has cooled molecules in the nebular gas to about one degree above absolute zero - colder than even the cosmic background radiation - making it the coldest region observed in the distant Universe. Shining with light from the central star reflected by dust, the frigid Boomerang Nebula is believed to be a star or stellar system evolving toward the planetary nebula phase.

This false-color image shows the chilliest region in the universe, as imaged in the Boomerang Nebula with the NTT/ESO telescope at La Silla, Chile through a V-band filter. The farther away you look from the central star, which is depicted here as a white square, the colder the temperature. The Boomerang contains gas and dust ejected by a Sun-like star in its death throes, and is seen here in starlight reflected by the dust particles.

The image is displayed on a log scale and color-coded. Blue represents the faintest regions, with yellow, red and white representing increasingly brighter regions. The bipolar lobes, seen representing the coldest regions, contain gas ejected from the central star and expanding at 590,000 kilometers per hour (370,000 miles per hour). This expansion cools the gas to below 3 Kelvin, or minus 458 degrees Fahrenheit, which is lower than the temperature of the cosmic microwave background radiation that pervades our universe. This allows carbon monoxide molecules in the nebular gas to absorb that background radiation. The absorption signal was detected using the 15-meter (49-foot) Swedish-ESO-Submillimeter Telescope at the European Space Observatory in La Silla, Chile.

There is a lot of structure in this nebula. It looks like a graph of hyperbolic functions. There is magnetism--it looks like a magnetic field as outlined by iron filings--but it also shows illumination of only part of the entire structure. There would be a lot more to this gas cloud that is not lighted.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.