Lista över protoplanetariska nebulosor

Egg Nebula.jpg
Resembling a rippling pool illuminated by underwater lights, the Egg Nebula (CRL 2688) offers astronomers a special look at the normally invisible dust shells swaddling an aging star. These dust layers, extending over one-tenth of a light-year from the star, have an onionskin structure that forms concentric rings around the star. A thicker dust belt, running almost vertically through the image, blocks off light from the central star. Twin beams of light radiate from the hidden star and illuminate the pitch-black dust, like a shining flashlight in a smoky room.

The artificial "Easter-Egg" colors in this image are used to dissect how the light reflects off the smoke-sized dust particles and then heads toward Earth.

Dust in our atmosphere reflects sunlight such that only light waves vibrating in a certain orientation get reflected toward us. This is also true for reflections off water or roadways. Polarizing sunglasses take advantage of this effect to block out all reflections, except those that align to the polarizing filter material. It's a bit like sliding a sheet of paper under a door. The paper must be parallel to the floor to pass under the door.

Hubble's Advanced Camera for Surveys has polarizing filters that accept light that vibrates at select angles. In this composite image, the light from one of the polarizing filters has been colored red and only admits light from about one-third of the nebula. Another polarizing filter accepts light reflected from a different swath of the nebula. This light is colored blue. Light from the final third of the nebula is from a third polarizing filter and is colored green. Some of the inner regions of the nebula appear whitish because the dust is thicker and the light is scattered many times in random directions before reaching us. (Likewise, polarizing sunglasses are less effective if the sky is very dusty).

By studying polarized light from the Egg Nebula, scientists can tell a lot about the physical properties of the material responsible for the scattering, as well as the precise location of the central (hidden) star. The fine dust is largely carbon, manufactured by nuclear fusion in the heart of the star and then ejected into space as the star sheds material. Such dust grains are essential ingredients for building dusty disks around future generations of young stars, and possibly in the formation of planets around those stars.

The Egg Nebula is located 3,000 light-years away in the constellation Cygnus. This image was taken with Hubble's Advanced Camera for Surveys in September and October 2002.

Frosty Leo Nebula.jpg
(c) ESA/Hubble & NASA, CC BY 4.0

Frosty Leo Nebula. Picture of IRAS 09371+1212, the Frosty Leo Nebula, a protoplanetary nebula using the Hubble Space Telescope's Advanced Camera for Surveys High-Resolution Channel (HRC).

Three thousand light-years from Earth lies the strange protoplanetary nebula IRAS 09371+1212, nicknamed the Frosty Leo Nebula. Despite their name, protoplanetary nebulae have nothing to do with planets: they are formed from material shed from their aging central star. The Frosty Leo Nebula has acquired its curious name as it has been found to be rich in water in the form of ice grains, and because it lies in the constellation of Leo.

This nebula is particularly noteworthy because it has formed far from the galactic plane, away from interstellar clouds that may block our view. The intricate shape comprises a spherical halo, a disc around the central star, lobes and gigantic loops. This complex structure strongly suggests that the formation processes are complex and it has been suggested that there could be a second star, currently unseen, contributing to the shaping of the nebula.

Protoplanetary nebulae like the Frosty Leo Nebula have brief lifespans by astronomical standards and are precursors to the planetary nebula phase, in which radiation from the star will make the nebula’s gas light up brightly. Their rarity makes studying them a priority for astronomers who seek to understand better the evolution of stars.

This picture was created from images taken with the High Resolution Channel of Hubble’s Advanced Camera for Surveys, which images a small area of sky (only 26 by 29 arcseconds) in high detail.

Redrectangle hst full.jpg
This file is in the public domain because it was created by NASA and ESA. NASA Hubble material (and ESA Hubble material prior to 2009) is copyright-free and may be freely used as in the public domain without fee, on the condition that only NASA, STScI, and/or ESA is credited as the source of the material. This license does not apply if ESA material created after 2008 or source material from other organizations is in use.

The material was created for NASA by Space Telescope Science Institute under Contract NAS5-26555, or for ESA by the Hubble European Space Agency Information Centre. Copyright statement at hubblesite.org or 2008 copyright statement at spacetelescope.org.

For material created by the European Space Agency on the spacetelescope.org site since 2009, use the {{ESA-Hubble}} tag.

Cottoncandynebula.jpg

The Twin Jet Nebula.jpg
(c) ESA/Hubble, CC BY 4.0
The Twin Jet Nebula, or PN M2-9, is a striking example of a bipolar planetary nebula. Bipolar planetary nebulae are formed when the central object is not a single star, but a binary system, Studies have shown that the nebula’s size increases with time, and measurements of this rate of increase suggest that the stellar outburst that formed the lobes occurred just 1200 years ago.

IRAS 19024+0044 - Potw1136a.tif
Författare/Upphovsman: ESA/Hubble, NASA and R. Sahai, Licens: CC BY 3.0
In the constellation of Aquila (the Eagle), lies a star nearing the end of its life that is surrounded by a starfish-shaped cloud of gas and dust. A striking image of this object, known as IRAS 19024+0044 has been captured by the NASA/ESA Hubble Space Telescope.

Protoplanetary nebulae offer glimpses of how stars similar to the Sun end their lives and how they make the transition to white dwarfs surrounded by planetary nebulae. As it ages, a Sun-like star eventually sheds its outer layers into space, creating a beautiful and often intricately shaped cloud of gas and dust around it. At first, still relatively cool, the star is unable to ionise this gas, which shines only by reflected and scattered stellar light. Only when the temperature of the star increases enough to ionise this protoplanetary nebula does the pattern of gas and dust become a fully fledged planetary nebula.

Protoplanetary nebulae are relatively rare and short-lived objects that provide astronomers with clues into how the often strangely asymmetric planetary nebulae are formed. Clearly visible in this image are five blue lobes that extend away from the central star and give the nebula its asymmetric starfish shape. While astronomers have come up with theories for the origin of these structures, such as direction-changing jets or explosive ejections of matter from the star, their formation is not entirely understood.

IRAS 19024+0044 is blue in colour as the blue component of the light coming from the star is more easily scattered by the gas and dust in the nebula, while the red and orange rays are relatively unaffected. This is similar to what happens to sunlight in the Earth’s atmosphere, giving the sky its distinctive shade of blue.

This picture was created from images taken with the High Resolution Channel of Hubble’s Advanced Camera for Surveys. It is a composite image created by the combination of exposures taken through a yellow–orange filter (F606W, coloured blue) and a near-infrared filter (F814W, coloured red). The total exposure times were 880 s and 140 s, respectively and the field of view is approximately 13 by 13 arcseconds.

Boomerang nebula.jpg

The Boomerang Nebula is a young planetary nebula and the coldest object found in the Universe so far. The NASA/ESA Hubble Space Telescope image is yet another example of how Hubble's sharp eye reveals surprising details in celestial objects.

This NASA/ESA Hubble Space Telescope image shows a young planetary nebula known (rather curiously) as the Boomerang Nebula. It is in the constellation of Centaurus, 5000 light-years from Earth. Planetary nebulae form around a bright, central star when it expels gas in the last stages of its life.

The Boomerang Nebula is one of the Universe's peculiar places. In 1995, using the 15-metre Swedish ESO Submillimetre Telescope in Chile, astronomers Sahai and Nyman revealed that it is the coldest place in the Universe found so far. With a temperature of -272C, it is only 1 degree warmer than absolute zero (the lowest limit for all temperatures). Even the -270C background glow from the Big Bang is warmer than this nebula. It is the only object found so far that has a temperature lower than the background radiation.

Keith Taylor and Mike Scarrott called it the Boomerang Nebula in 1980 after observing it with a large ground-based telescope in Australia. Unable to see the detail that only Hubble can reveal, the astronomers saw merely a slight asymmetry in the nebula's lobes suggesting a curved shape like a boomerang. The high-resolution Hubble images indicate that 'the Bow tie Nebula' would perhaps have been a better name.

The Hubble telescope took this image in 1998. It shows faint arcs and ghostly filaments embedded within the diffuse gas of the nebula's smooth 'bow tie' lobes. The diffuse bow-tie shape of this nebula makes it quite different from other observed planetary nebulae, which normally have lobes that look more like 'bubbles' blown in the gas. However, the Boomerang Nebula is so young that it may not have had time to develop these structures. Why planetary nebulae have so many different shapes is still a mystery.

The general bow-tie shape of the Boomerang appears to have been created by a very fierce 500 000 kilometre-per-hour wind blowing ultracold gas away from the dying central star. The star has been losing as much as one-thousandth of a solar mass of material per year for 1500 years. This is 10-100 times more than in other similar objects. The rapid expansion of the nebula has enabled it to become the coldest known region in the Universe.

The image was exposed for 1000 seconds through a green-yellow filter. The light in the image comes from starlight from the central star reflected by dust particles.

Silkworm Nebula - Opo9811g.tif
(c) ESA/Hubble & NASA, CC BY 4.0

The Silkworm Nebula

The Hubble Space Telescope's Wide Field and Planetary Camera 2has captured images of the birth of two planetary nebulae as they emerge from wrappings of gas and dust, like butterflies breaking out of their cocoons.

Credit:

Sun Kwok and Kate Su (University of Calgary), Bruce Hrivnak (Valparaiso University), and NASA/ESA