This is a false color image
of the planetary nebula NGC 6778.
«NGC6778,» adds another of the authors, Hektor Monteiro, of the University fo Itajubá, Brazil, «is one
of the planetary nebulae with the brightest recombination lines.
As big planetary nebulae are the most common, we will use our new scale in making an unbiased census
of planetary nebulae in the Milky Way, which will then help answer some important research questions.»
To try to corroborate this theory, an image of the emission
of a planetary nebula in the recombination lines of oxygen has been obtained with the GTC.
That's according to a new explanation of the behaviour
of planetary nebulae — bubbles of gas sloughed off by dying stars (pictured).
Invisible dark matter may have started out as hot white dwarfs like this one in the middle
of planetary nebula NGC 2440.
Astronomers were thrilled when they first saw the Hubble images
of the planetary nebulas ngc 7027 and crl 2688, also known as the Egg nebula.
The astronomers suggest that the orderly behaviour
of the planetary nebulae could have been caused by the presence of strong magnetic fields as the bulge formed.
«Bizarre alignment
of planetary nebulae.»
Many
of these planetary nebulas have a funny kind of inverted mirror symmetry, with their tops and bottoms reflected and then reversed, as in the letter s.
After a few hours or weeks, depending on how super the supercomputer is, a thousand years
of planetary nebula history is waiting in the computer's memory to be studied in detail.
The ESO's Very Large Telescope (VLT) has captured a beautiful image
of a planetary nebula known as NGC 7009, or the Saturn Nebula, as part of a wider study attempting to unravel the processes that give these vast cosmic clouds of dust and glowing gas their distinctive shape.
Hubble's Wide Field Planetary Camera 2 captured this image
of planetary nebula NGC 2440 on Feb. 6, 2007.
The spectacular structure
of the planetary nebula contains the outer layers of a star that were expelled into interstellar space.
The stars which are even older have dissipated into a more diffuse background; this includes intermediate population I stars, older star clusters and the younger representatives
of the planetary nebulae.
NIRES Principal Investigator Keith Matthews of Caltech (left) with W. M. Keck Observatory Director Hilton Lewis (right) after successfully achieving «first light» with a spectral image
of planetary nebula NGC 7027.
Dense knots of gas and dust seem to be a natural part of the evolution
of planetary nebulae.
NGC 3132 is a striking example
of a planetary nebula.
The Keck Observatory - Caltech NIRES team just completed the instrument's first set of commissioning observations and achieved «first light» with a spectral image
of the planetary nebula NGC 7027.
With this image of NGC 6210, the Hubble telescope has added another bizarre form to the rogues» gallery
of planetary nebulae: a turtle swallowing a seashell.
The star lies at a center
of a planetary nebula, formed after the star's red giant stage about 8,300 years ago.
Not exact matches
At that point, it will partly collapse, blow its outer shells
of plasmatic gas into space, turn into a white dwarf, and begin to form a
planetary nebula in its surroundings.
In contrast, Immanuel Kant and Pierre de Laplace argued that
planetary development was part
of a normal process to be expected in the life
of almost every star: they assumed the young sun was surrounded by a thin lens - shaped gaseous envelope (solar
nebula) which later condensed into planets.
Chemical calculations show that helium hydride should be visible in clouds around distant galaxies and supernovas, or even in modern
planetary nebulas (shells
of gas expelled by aged, sunlike stars).
Ghostly and beautiful
planetary nebulae» have nothing to do with planets but acquired this name because these glowing spheres
of ionized gas resembled planets to early observers.
More accurate distances between the most common type
of «
planetary nebulae» and the Earth can be estimated simply with three sets
of data: firstly, the size
of the object on the sky taken from the latest high resolution surveys; secondly, an accurate measurement
of how bright the object is in the red hydrogen - alpha emission line; and thirdly, an estimate
of the dimming toward the
nebula caused by so called interstellar - reddening.
«To do this,» explains Antonio Cabrera Lavers, head
of astronomy at the GTC and one
of the authors
of the paper, «we have used for the first time the blue tunable filter
of OSIRIS to take a deep image centred on the emission from the recombination lines
of one
of the oxygen ions in the
planetary nebula 6778.»
That phase is called the proto -
planetary nebula, and is so short that only a few
of these objects are known.
Dr David Frew, Professor Quentin Parker and Dr Ivan Bojicic, based on a culmination
of ten years
of research work, developed a new method for measuring more accurate distances between «
planetary nebulae» and the Earth.
Very soon, perhaps in the next millennium or two, the star you can see in the center will shed those last bits
of gas on top
of it, exposing it fully to space, and the weird lobes
of material will glow far more brightly, becoming a
planetary nebula proper.
«The first image
of a new gaseous component in a
planetary nebula.»
This is combined with the use
of the authors» own robust techniques to effectively remove «doppelgangers» and mimics that have seriously contaminated previous
planetary nebulae catalogues, which added considerable scatter to previous statistical distance scales.
«During the past few years our group,» says David Jones, an astrophysicist at the IAC and another
of the authors on the paper, «has discovered that the
planetary nebulae with the biggest discrepancies in their abundances are usually associated with binary central stars which have been through a phase with a common envelope, that is to say the process
of expansion
of the more massive
of the two stars has meant that the other star is orbiting within its outer atmosphere, and the viscosity has brought the stars very close to one another.
Based on a culmination
of ten years
of research work, the new method to estimate more accurate distances between
planetary nebulae and the Earth developed by HKU astronomers promises a new era in scientists» ability to study and understand the fascinating if brief period in the final stages
of the lives
of low - and mid-mass stars.
After shining for many millions
of years, stars end their lives, mainly, in two ways: very high mass stars die very violently as supernovae, while low mass stars end as
planetary nebulae.
While globular clusters are billions
of years old, the
planetary nebula phase
of a star's life only lasts for a few thousand years, so it's exceedingly rare to find them in globulars.
The first author
of this research Dr David Frew, Research Assistant Professor, Department
of Physics said: «measuring distances to Galactic «
planetary nebulae» has been an intractable problem for many decades, because
of the extremely diverse nature
of both the
nebulae themselves and their central stars.
Planetary nebulae, which got their name after being misidentified by early astronomers, are formed when an ageing star weighing up to eight times the mass
of the sun ejects its outer layers as clouds
of luminous gas (see Why stars go out in a blaze
of glory).
This is because pockets
of gas rich in heavy elements would be created if a comet in the outer regions
of a solar system got vaporised by a dying star in its red giant phase or by the expanding
planetary nebula that follows it (arxiv.org/abs/1001.4513).
For this shot
of the Ant
Nebula, Schmidt started with typical Hubble data sets and combined them to achieve these colors, while also adjusting the color balance and sharpening the details to create an original view of the symmetrical planetary nebula, the remains of a star that blew itself to p
Nebula, Schmidt started with typical Hubble data sets and combined them to achieve these colors, while also adjusting the color balance and sharpening the details to create an original view
of the symmetrical
planetary nebula, the remains of a star that blew itself to p
nebula, the remains
of a star that blew itself to pieces.
[5] Since the discovery
of Pease 1, only three other globular clusters have been found to host
planetary nebulae: Messier 22, NGC 6441, and Palomar 6.
As well as this black hole, Messier 15 is known to house a
planetary nebula, Pease 1 [4]-- and it was the first globular known to contain one
of these objects [5].
By studying the jets from pre-
planetary and
planetary nebulae, Blackman and Lucchini were able to connect the energy and momentum involved in the accretion process with that in the jets; the process
of accretion is what in effect provides the fuel for these jets.
In
planetary nebulae, thought to be the evolved stage
of pre-
planetary nebula, the core is exposed and the hotter radiation it emits ionises the gas in the now weaker jets, which in turn glow.
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.
«Pre-
planetary» and «
planetary»
nebulae are different in the nature
of the light they produce; pre-
planetary nebulae reflect light, whereas mature
planetary nebulae shine through ionisation (where atoms lose or gain electrons).
Soon it collides with the slower, cooler gas ahead
of it, piling it up into a bright, dense cloud called a
planetary nebula.
Its ultraviolet light detectors will reveal the composition
of interstellar gas, the cores
of galaxies and quasars, the outer atmospheres
of cool stars and planets,
planetary nebulas, and supernovas.
Hubble observations over the past two decades have revealed an enormous complexity and diversity
of structure in
planetary nebulae.
For decades, astronomers have suspected that
planetary nebulae — dazzlingly colorful shrouds
of gas cast off by dying stars — owe their weird but often symmetrical shapes to the sculpting magnetic forces
of two stars orbiting each other at the
nebula's center.