Tag: Planetary nebula

Astronomy Picture of the Day – The Medusa Nebula

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 June 17

The Medusa Nebula
Image Credit & Copyright: European Southern Observatory, VLT

 

Explanation: Braided, serpentine filaments of glowing gas suggest this nebula’s popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away along the southern border of the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun, as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. An unrelated, bright, foreground star is near center in this close-up, telescopic view, while the Medusa’s transforming central star is actually the dimmer star below center and toward the right-hand part of the frame. The Medusa Nebula is estimated to be over 4 light-years across.

Astronomy Picture of the Day for December 27th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 December 27
See Explanation. Clicking on the picture will download the highest resolution version available.

M27: The Dumbbell Nebula
Image Credit & Copyright: Bill Snyder (Bill Snyder Photography) 

Explanation: The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier’s list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen toward the constellation of the Fox (Vulpecula) with binoculars. It takes light about 1000 years to reach us from M27, shown above in colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star’s gaseous outer-envelope, leaving an X-ray hot white dwarf.

NASA Image of the Day for Oct. 4th – Ring Holds a Delicate Flower

Ring Holds a Delicate Flower

NASA’s Spitzer Space Telescope finds a delicate flower in the Ring Nebula, as shown in this image. The outer shell of this planetary nebula looks surprisingly similar to the delicate petals of a camellia blossom. (A planetary nebula is a shell of material ejected from a dying star.) Located about 2,000 light years from Earth in the constellation Lyra, the Ring Nebula is also known as Messier Object 57 and NGC 6720. It is one of the best examples of a planetary nebula and a favorite target of amateur astronomers.

The “ring” is a thick cylinder of glowing gas and dust around the doomed star. As the star begins to run out of fuel, its core becomes smaller and hotter, boiling off its outer layers. Spitzer’s infrared array camera detected this material expelled from the withering star. Previous images of the Ring Nebula taken by visible-light telescopes usually showed just the inner glowing loop of gas around the star. The outer regions are especially prominent in this new image because Spitzer sees the infrared light from hydrogen molecules. The molecules emit the infrared light that they have absorbed ultraviolet radiation from the star or have been heated by the wind from the star.

Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA