Posts Tagged ‘planetary nebula’

Chance Meeting Creates Celestial Diamond Ring

Credit: ESO

Credit: ESO

Astronomers using ESO’s Very Large Telescope in Chile have captured this eye-catching image of planetary nebula PN A66 33 — usually known as Abell 33. Created when an aging star blew off its outer layers, this beautiful blue bubble is, by chance, aligned with a foreground star, and bears an uncanny resemblance to a diamond engagement ring. This cosmic gem is unusually symmetric, appearing to be almost circular on the sky.

Most stars with masses similar to that of our Sun will end their lives as white dwarfs — small, very dense, and hot bodies that slowly cool down over billions of years. On the way to this final phase of their lives the stars throw their atmospheres out into the space and create planetary nebulae, colourful glowing clouds of gas surrounding the small, bright stellar relics.

This image, captured by ESO’s Very Large Telescope (VLT), shows the remarkably round planetary nebula Abell 33, located roughly 2500 light-years from Earth. Being perfectly round is uncommon for these objects — usually something disturbs the symmetry and causes the planetary nebula to display irregular shapes.

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How Stellar Death Can Lead To Twin Celestial Jets

February 13, 2014 Leave a comment

Credit: NASA/ESA & Valentin Bujarrabal

Credit: NASA/ESA & Valentin Bujarrabal

Astronomers know that while large stars can end their lives as violently cataclysmic supernovae, smaller stars end up as planetary nebulae – colourful, glowing clouds of dust and gas. In recent decades these nebulae, once thought to be mostly spherical, have been observed to often emit powerful, bipolar jets of gas and dust. But how do spherical stars evolve to produce highly aspherical planetary nebulae?

In a theoretical paper published this week in the Monthly Notices of the Royal Astronomical Society, a University of Rochester professor and his undergraduate student conclude that only “strongly interacting” binary stars – or a star and a massive planet – can feasibly give rise to these powerful jets.

When these smaller stars run out of hydrogen to burn they begin to expand and become Asymptotic Giant Branch (AGB) stars. This phase in a star’s life lasts at most 100,000 years. At some point some of these AGB stars, which represent the distended last spherical stage in the lives of low mass stars, become “pre-planetary” nebula, which are aspherical.

“What happens to change these spherical AGB stars into non-spherical nebulae, with two jets shooting out in opposite directions?” asks Eric Blackman, professor of physics and astronomy at Rochester. “We have been trying to come up with a better understanding of what happens at this stage.”

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Magnetic Jet Shows How Stars Begin Their Final Transformation

September 19, 2013 Leave a comment

Credits: E. Lagadec/ESO/A. Pérez Sánchez

Credits: E. Lagadec/ESO/A. Pérez Sánchez

An international team of astronomers have for the first time found a jet of high-energy particles emanating from a dying star. The discovery, by a collaboration of scientists from Sweden, Germany and Australia, is a crucial step in explaining how some of the most beautiful objects in space are formed – and what happens when stars like the sun reach the end of their lives. The researchers publish their results in the journal Monthly Notices of the Royal Astronomical Society.

At the end of their lives, stars like the sun transform into some of the most beautiful objects in space: amazing symmetric clouds of gas called planetary nebulae. But how planetary nebulae get their strange shapes has long been a mystery to astronomers.

Scientists at Chalmers University of Technology in Sweden have together with colleagues from Germany and Australia discovered what could be the key to the answer: a high-speed, magnetic jet from a dying star.

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NGC 2392: A Beautiful End To A Star’s Life

Credit: X-ray (NASA/CXC/IAA-CSIC/N.Ruiz et al,); Optical (NASA/STScI)

Credit: X-ray (NASA/CXC/IAA-CSIC/N.Ruiz et al,); Optical (NASA/STScI)

Stars like the Sun can become remarkably photogenic at the end of their life. A good example is NGC 2392, which is located about 4,200 light years from Earth. NGC 2392, (nicknamed the “Eskimo Nebula”) is what astronomers call a planetary nebula. This designation, however, is deceiving because planetary nebulas actually have nothing to do with planets. The term is simply a historic relic since these objects looked like planetary disks to astronomers in earlier times looking through small optical telescopes.

Instead, planetary nebulas form when a star uses up all of the hydrogen in its core — an event our Sun will go through in about five billion years. When this happens, the star begins to cool and expand, increasing its radius by tens to hundreds of times its original size. Eventually, the outer layers of the star are carried away by a 50,000 kilometer per hour wind, leaving behind a hot core. This hot core has a surface temperature of about 50,000 degrees Celsius, and is ejecting its outer layers in a much faster wind traveling six million kilometers per hour. The radiation from the hot star and the interaction of its fast wind with the slower wind creates the complex and filamentary shell of a planetary nebula. Eventually the remnant star will collapse to form a white dwarf star.

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A Valentine Rose

February 12, 2013 1 comment

Credit: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

Credit: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

This image of a planetary nebula, which may suggest a rose to some, was obtained with the wide-field view of the National Optical Astronomy Observatory (NOAO) Mosaic 1 camera on the Mayall 4-meter telescope at Kitt Peak National Observatory.

Sh2-174 is an unusual ancient planetary nebula. A planetary nebula is created when a low-mass star blows off its outer layers at the end of its life. The core of the star remains and is called a white dwarf. Usually the white dwarf can be found very near the center of the planetary nebula. But in the case of Sh2-174 it is off to the right.

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Born-Again Star Foreshadows Fate Of Solar System

November 21, 2012 Leave a comment

Credit: NASA/ESA Hubble Space Telescope and X-ray data from ESA’s XMM-Newton and NASA’s Chandra space telescopes

Astronomers have found evidence for a dying Sun-like star coming briefly back to life after casting its gassy shells out into space, mimicking the possible fate our own Solar System faces in a few billion years. This new picture of the planetary nebula Abell 30, located 5500 light-years from Earth, is a composite of visible images.

‘Planetary nebula’ is the name given to the often-concentric shells of stellar material cast into space by dying stars. To astronomers of the 18th century, these objects looked like the colourful ‘blob’ of a planet through their telescopes, and the name stuck.

Astronomers now know that as a star with less than eight times the mass of the Sun swells into a red giant towards the end of its life, its outer layers are expelled via pulsations and winds.

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NASA’s SOFIA Captures Images of the Planetary Nebula M2-9

Image Credit: NASA / DLR / USRA / DSI / FORCAST team / M. Werner, J. Rho

Image Credit: NASA / DLR / USRA / DSI / FORCAST team / M. Werner, J. Rho

Researchers using NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) have captured infrared images of the last exhalations of a dying sun-like star.

The object observed by SOFIA, planetary nebula Minkowski 2-9, or M2-9 for short, is seen in this three-color composite image. The SOFIA observations were made at the mid-infrared wavelengths of 20, 24, and 37 microns. The 37-micron wavelength band detects the strongest emissions from the nebula and is impossible to observe from ground-based telescopes.

Objects such as M2-9 are called planetary nebulae due to a mistake made by early astronomers who discovered these objects while sweeping the sky with small telescopes. Many of these nebulae have the color, shape and size of Uranus and Neptune, so they were dubbed planetary nebulae. The name persists despite the fact that these nebulae are now known to be distant clouds of material, far beyond our solar system, that are shed by stars about the size of our sun undergoing upheavals during their final life stages.

Although the M2-9 nebular material is flowing out from a spherical star, it is extended in one dimension, appearing as a cylinder or hourglass. Astronomers hypothesize that planetary nebulae with such shapes are produced by opposing flows of high-speed material caused by a disk of material around the dying star at the center of the nebula. SOFIA’s observations of M2-9 were designed to study the outflow in detail with the goal of better understanding this stellar life cycle stage that is important in our galaxy’s evolution.

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The Helix in New Colours

January 19, 2012 Leave a comment

ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit

ESO’s VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.

The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image.

The nebula itself is a complex object composed of dust, ionised material as well as molecular gas, arrayed in a beautiful and intricate flower-like pattern and glowing in the fierce glare of ultraviolet light from the central hot star.

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