A Plethora Of Planetary Nebula.
When it comes to art, there’s nothing more impressive than what the Universe can paint. In this gallery, four planetary nebulae are featured an d aren’t they stunning!
These beautiful subjects of the first systematic survey of dying stars taken by NASA’s Chandra X-Ray Observatory. Their names are NGC 6543, NGC 7662, NGC 7009 and NGC 6826. Despite their ordinary catalog numbers, they are anything but plain. These incredible visions are a composite of the purple-colored X-ray emissions from Chandra and the red, green and blue optical emission contributed by the Hubble Space Telescope.
Just what are these exotic deep space objects? You don’t have to look much further than our Sun to understand. A planetary nebula is what will occur several billion years from now when our star depletes its core hydrogen and expands into a red giant star. At that time, it will grow to tens to hundreds of times larger than its present size. During this phase of its lifetime, it will shed most of its outer layers, leaving a hot core which will eventually contract and form a dense white dwarf star. Now intense stellar winds will begin to radiate outward from the core, slamming into the skinned atmosphere and pushing it away. This creates the delicate ribbons and folds… the shell we see with an optical telescope.
However, Chandra doesn’t “see” in the optical. It captures diffuse X-ray emissions which comprises about a third of the planetary nebula captured in the survey. All the members seen here are caused by shock waves, the fantasy structure carved from the ejected material when impacted by the speeding stellar winds.
The new survey reveals that optical images of the majority of planetary nebula which also contain diffuse X-ray emissions have compact shells with highly defined rims enveloped by fainter halos. All compact shell structures observed are less than 5000 years old… an age which seems to suggest a timescale for intense shock waves to occur.
In addition, around half of the planetary nebula in the survey shown something else – an X-ray point source located in the center. All but one of these show high energy X-rays which might be the handiwork of a companion star. These findings could mean that a majority of central stars which eject planetary nebula have a companion.
News? Not quite. However, further studies will help astronomers understand the importance of double stars and how they may shape the structure and evolution of these beautiful cosmic characters.
Original Story Source: Chandra X-Ray Observatory News Release. Submitted by Tammy Plotner for “Dave Reneke’s World of Space and Astronomy News”.