Archive

Archive for the ‘Nebulae’ Category

ALMA Reveals Ghostly Shape Of ‘Coldest Place In The Universe’

October 24, 2013 Leave a comment

Credit: Bill Saxton; NRAO/AUI/NSF; NASA/Hubble; Raghvendra Sahai

Credit: Bill Saxton; NRAO/AUI/NSF; NASA/Hubble; Raghvendra Sahai

At a cosmologically crisp one degree Kelvin (minus 458 degrees Fahrenheit), the Boomerang Nebula is the coldest known object in the Universe – colder, in fact, than the faint afterglow of the Big Bang, which is the natural background temperature of space.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope have taken a new look at this intriguing object to learn more about its frigid properties and to determine its true shape, which has an eerily ghost-like appearance.

As originally observed with ground-based telescopes, this nebula appeared lopsided, which is how it got its name. Later observations with the Hubble Space Telescope revealed a bow-tie-like structure. The new ALMA data, however, reveal that the Hubble image tells only part of the story, and the twin lobes seen in that image may actually be a trick of the light as seen at visible wavelengths.

Link To Full Story

Advertisements

A Close Look At The Toby Jug Nebula

October 9, 2013 Leave a comment

Credit: ESO

Credit: ESO

Located about 1200 light-years from Earth in the southern constellation of Carina (The Ship’s Keel), the Toby Jug Nebula, more formally known as IC 2220, is an example of a reflection nebula. It is a cloud of gas and dust illuminated from within by a star called HD 65750. This star, a type known as a red giant, has five times the mass of our Sun but it is in a much more advanced stage of its life, despite its comparatively young age of around 50 million years.

The nebula was created by the star, which is losing part of its mass out into the surrounding space, forming a cloud of gas and dust as the material cools. The dust consists of elements such as carbon and simple, heat-resistant compounds such as titanium dioxide and calcium oxide (lime). In this case, detailed studies of the object in infrared light point to silicon dioxide (silica) being the most likely compound reflecting the star’s light.

IC 2220 is visible as the star’s light is reflected off the grains of dust. This celestial butterfly structure is almost symmetrical, and spans about one light-year. This phase of a star’s life is short-lived and such objects are thus rare.

Link To Full Story

Coma Cluster: Clues To The Growth Of The Colossus In Coma

September 19, 2013 Leave a comment

Credit: ESO. Acknowledgement: Martin Pugh

Credit: ESO. Acknowledgement: Martin Pugh

Located around 6000 light-years from Earth in the constellation of Scorpius (The Scorpion), the nebula formally known as IC 4628 is a huge region filled with gas and clumps of dark dust. These gas clouds are star-forming regions, producing brilliant hot young stars. In visible light, these stars appear as a blue-white colour, but they also emit intense radiation in other parts of the spectrum — most notably in the ultraviolet.

It is this ultraviolet light from the stars that causes the gas clouds to glow. This radiation strips electrons from hydrogen atoms, which then later recombine and release energy in the form of light. Each chemical element emits light at characteristic colours when this process occurs, and for hydrogen the predominant colour is red. IC 4628 is an example of an HII region.

Over the last few million years this region of sky has formed many stars, both individually and in clusters. There is a large scattered star cluster named Collinder 316 which extends over most of this image. This cluster is a part of a much larger gathering of very hot and luminous stars. Also visible are many dark structures or cavities, where interstellar matter has been blown away by the powerful winds generated by the nearby hot stars.

Link To Full Story.

The World’s First Interferometric Image At 500 GHz With ALMA Band 8 Receivers

September 3, 2013 1 comment

Credit: ALMA (ESO/NAOJ/NRAO)

Credit: ALMA (ESO/NAOJ/NRAO)

ALMA opens another window to the universe in the 500 GHz frequency band. Astronomers successfully synthesized the distribution of atomic carbon around a planetary nebula NGC 6302 in test observations with the ALMA Band 8 receiver, developed by the National Astronomical Observatory of Japan (NAOJ). This is the first 500 GHz band astronomical image captured by a radio interferometer with unprecedentedly high resolution.

NGC 6302 is a planetary nebula, which is in the final stage of the life of a star with a mass several times that of the Sun. Visible light image shows a bipolar shape of gas ejected from the dying star. ALMA with the Band 8 receivers targeted at the center of the nebula and revealed that the distribution of carbon atom is concentrated in a small part, which is similar to a dust and gas disk around the central star that has been found by previous observations with other telescopes. Further observations of carbon atom with better resolution will give us more detailed view of the chemical environment in the nebula.

Full Story: http://www.nao.ac.jp/en/news/topics/2013/20130902-alma-band8.html

Two Very Different Gas Clouds In The Galaxy Next Door


Credit: ESO

Credit: ESO

ESO’s Very Large Telescope has captured an intriguing star-forming region in the Large Magellanic Cloud — one of the Milky Way’s satellite galaxies. This sharp image reveals two distinctive glowing clouds of gas: red-hued NGC 2014, and its blue neighbour NGC 2020. While they are very different, they were both sculpted by powerful stellar winds from extremely hot newborn stars that also radiate into the gas, causing it to glow brightly.

This image was taken by the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile — the best place in the southern hemisphere for astronomical observing. But even without the help of telescopes like the VLT, a glance towards the southern constellation of Dorado (The Swordfish or Dolphinfish [1]) on a clear, dark night reveals a blurry patch which, at first sight, appears to be just like a cloud in the Earth’s atmosphere.

At least, this may have been explorer Ferdinand Magellan’s first impression during his famous voyage to the southern hemisphere in 1519. Although Magellan himself was killed in the Philippines before his return, his surviving crew announced the presence of this cloud and its smaller sibling when they returned to Europe, and these two small galaxies were later named in Magellan’s honour. However, they were undoubtedly seen by both earlier European explorers and observers in the southern hemisphere, although they were never reported.

Full Story and Images: http://www.eso.org/public/news/eso1335/

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.

Full Story, Images, and Links: http://www.chandra.harvard.edu/photo/2013/ngc2392/

Cat’s Paw Nebula “Littered” With Baby Stars


Credit: S. Willis (CfA); NASA/JPL-Caltech/SSC

Credit: S. Willis (CfA); NASA/JPL-Caltech/SSC

Most skygazers recognize the Orion Nebula, one of the closest stellar nurseries to Earth. Although it makes for great views in backyard telescopes, the Orion Nebula is far from the most prolific star-forming region in our galaxy. That distinction may go to one of the more dramatic stellar nurseries like the Cat’s Paw Nebula, otherwise known as NGC 6334, which is experiencing a “baby boom.”

“NGC 6334 is forming stars at a more rapid pace than Orion – so rapidly that it appears to be undergoing what might be called a burst of star formation,” said lead author Sarah Willis of the Harvard-Smithsonian Center for Astrophysics (CfA) and Iowa State University. “It might resemble a ‘mini-starburst,’ similar to a scaled-down version of the spectacular bursts sometimes seen in other galaxies.”

NGC 6334 is a realm of extremes. The nebula contains about 200,000 suns’ worth of material that is coalescing to form new stars, some with up to 30 to 40 times as much mass as our Sun. It houses tens of thousands of recently formed stars, more than 2,000 of which are extremely young and still trapped inside their dusty cocoons. Most of these stars are forming in clusters where the stars are spaced up to a thousand times closer than the stars in the Sun’s neighborhood.

Full Story: http://www.cfa.harvard.edu/news/2013/pr201315.html