This is an image of MyCn18, a young planetary nebula located about 8,000 light-years away, taken with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). This Hubble image reveals the true shape of MyCn18 to be an hourglass withThe sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief but spectacular closing phase of MyCn18 - better known as the Engraved Hourglass Nebula - occurs as its outer layers are ejected. Located 8,000 light-years away from Earth in the southern constellation Musca, the sun-like star's core is in the process of becoming a cooling, fading white dwarf.
Astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae in the mid-1990s, including this one.
Delicate rings of colourful glowing gas - nitrogen-red, hydrogen-green, and oxygen-blue - outline the tenuous walls of the hourglass.
The unprecedented sharpness of Hubble's image has revealed surprising details of the nebula ejection process.
And it is these that are helping scientists to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebula.
MyCn18 was discovered by Annie Jump Cannon and Margaret W Mayall during their research on an extended Henry Draper Catalogue, an astronomical star encyclopedia compiled between 1918 and 1924.
The astronomers described it as a small faint planetary nebula, but the march of technology allowed scientists Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory to capture this stunning image using Hubble in January 1996. MyCn18's hourglass shape is thought to have arisen from the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles.
Life on Earth was made possible by the death of stars. Atoms like carbon and oxygen were expelled in the last few dying gasps of stars after their final supplies of hydrogen fuel were used up. How this star-stuff came together to form life is still a mystery, but scientists know that certain atomic combinations were necessary. Water – two hydrogen atoms linked to one oxygen atom -was vital to the development of life on Earth, and so NASA missions now search for water on other worlds in the hopes of finding life elsewhere. Organic molecules built mostly of carbon atoms are also thought to be important, since all life on Earth is carbon-based.
The most popular theories of the origin of life say the necessary chemistry occurred at hydrothermal vents on the ocean floor or in some sunlit shallow pool. However, discoveries in the past few years have shown that many of the basic materials for life form in the cold depths of space, where life as we know it is not possible.
After dying stars belch out carbon, some of the carbon atoms combine with hydrogen to form polycyclic aromatic hydrocarbons (PAHs). PAHs — a kind of carbon soot similar to the scorched portions of burnt toast — are the most abundant organic compounds in space, and a primary ingredient of carbonaceous chondrite meteorites. Although PAHs aren’t found in living cells, they can be converted into quinones, molecules that are involved in cellular energy processes. For instance, quinones play an essential role in photosynthesis, helping plants turn light into chemical energy.
The transformation of PAHs occurs in interstellar clouds of ice and dust. After floating through space, PAH soot eventually condenses into these "dense molecular clouds." The material in these clouds blocks out some but not all of the harsh radiation of space. The radiation that does filter through modifies the PAHs and other material in the clouds.
Infrared and radio telescope observations of the clouds have detected the PAHs, as well as fatty acids, simple sugars, faint amounts of the amino acid glycine, and over 100 other molecules, including water, carbon monoxide, ammonia, formaldehyde, and hydrogen cyanide.
The clouds have never been sampled directly — they’re too far away — so to confirm what is occurring chemically in the clouds, a research team led by Max Bernstein and Scott Sandford at the Astrochemistry Laboratory at NASA’s Ames Research Center set up experiments to mimic the cloud conditions.
In one experiment, a PAH/water mixture is vapor-deposited onto salt and then bombarded with ultraviolet (UV) radiation. This allows the researchers to observe how the basic PAH skeleton turns into quinones. Irradiating a frozen mixture of water, ammonia, hydrogen cyanide, and methanol (a precursor chemical to formaldehyde) generates the amino acids glycine, alanine and serine — the three most abundant amino acids in living systems.
For the award-winning writer George Saunders, the process of crafting a good story means not condescending to your reader. It means creating sentences that clue them into something unnoticed about the character, and allowing them to figure it out. “A bad story is one where you know what the story is and you're sure of it," he says in this short film, George Saunders: On Story. For Saunders, storytelling is a stand-in for day-to-day life—and the same considerations you take when approaching how to tell a story mirror the freedom to self-determined identity that you give your loved ones.
I love shopping online. No lines, no crowds, no searching for my size in a ransacked store display. Now, I don't spend a lot of money, as a general rule. But when I have to shop for other people, it's so easy to say, Oh, I should go ahead and buy this for myself while I'm at it. You can imagine the
PsychCentral.com (blog) The Power of the Written Word: Healing Through Journal-Writing PsychCentral.com (blog) The Power of the Written Word At the age of 18, I was sexually molested and exploited by my coach's husband.
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