The Very Large Array

The Karl G. Jansky Very Large Array (VLA) is a radio astronomy observatory located on the Plains of San Agustin, between the towns of Magdalena and Datil, some fifty miles (80 km) west of Socorro, New Mexico, USA. The VLA has made key observations of black holes and protoplanetary disks around young stars, discovered magnetic filaments and traced complex gas motions at the Milky Way’s center, probed the Universe’s cosmological parameters, and provided new knowledge about the physical mechanisms that produce radio emission.

The VLA stands at an elevation of 6970 ft (2124 m) above sea level. It is a component of the National Radio Astronomy Observatory (NRAO).

U.S. Route 60 passes through the complex, which is adjacent to the Boy Scout Double H High Adventure Base.

The observatory consists of 27 independent antennas, each of which has a dish diameter of 25 meters (82 feet) and weighs 209 metric tons (230 Short tons). The antennas are arrayed along the three arms of a Y-shape (each of which measures 21 km/13 miles long). Using the rail tracks that follow each of these arms—and that, at one point, intersect with U.S. Route 60 at a level crossing—and a specially designed lifting locomotive (“Hein’s Trein”), the antennas can be physically relocated to a number of prepared positions, allowing aperture synthesis interferometry with a maximum baseline of 36 km (22 mi): in essence, the array acts as a single antenna with that diameter. The smallest angular resolution that can be reached is about 0.05 arcseconds at a wavelength of 7 mm.

sciencesoup:

A Moving Perspective

Stop for a moment, and let me tell you the story of you. You were born in the heart of a star, in a brilliant white furnace that churned and trembled and dazzled the darkness. Every atom in your body was cooked in a stellar crucible as dense as fifty elephants crammed inside a thimble, and then, as its world raged and shook, the star tore open its own heart for you, exploding suicidal atoms far across the oceans of the universe—atoms that came to reside in you. The remnants of such a dead star—a vast cloud of stellar gas and dust—acted as a nursery for our solar system too, forming the sun and the planets swirling around it over billions of years. You’re just clinging to the crust of this rocky world, encased in the blue skin of its atmosphere. You’re fresh on the crest of of tens of thousands of generations, and you’re moving faster than you could ever imagine. The earth beneath your feet is spinning at 1,600 km/h, the planet is hurtling around the sun at 107,500 km/h, the sun is moving towards Vega at 70,000 km/h, the Orion arm of our spiral galaxy is rotating at 900,000 km/h, and the Milky Way is heading for the Andromeda galaxy at 3,600,000 km/h…. And still here you are—a lovely collection of atoms, a perfect composition of organic molecules, a child of the stars themselves. You are the universe, every speck of you, and in a hundred billion galaxies, there is not another like you. 

Moon Meets Morning Star

Rising in the dark hours before dawn, wandering Venus now shines as the brilliant morning star. Its close conjunction with the Moon on August 13 was appreciated around planet Earth. But skygazers in eastern Asia were also treated to a lunar occultation, the waning crescent Moon passing directly in front of the bright planet in still dark skies from above the city lights and clouds over Taebaek, Korea. The occultation begins near the horizon and progresses as the pair rises. Venus first disappears behind the Moon’s sunlit crescent, emerging before dawn from the dark lunar limb.

Credit & Copyright: Kwon, O Chul (TWAN)

Conjunction Colours 

During the past week, nightfall on planet Earth has featured Mars, Saturn, and Spica in a lovely conjunction near the western horizon. Still forming the corners of a distinctive celestial triangle after sunset and recently joined by a crescent Moon, they are all about the same brightness but can exhibit different colors to the discerning eye. This ingenious star trail image was recorded as the trio set on August 12 with a telephoto lens from the shores of Lake Eppalock, in central Victoria, Australia. Focused on foreground eucalyptus trees, the image slightly blurs the trails to show more saturated colors. Can you guess which trail is which? Of course the reddest trail is Mars, with Saturn on the right a paler echo of the Red Planet’s hue. Left is hot and luminous Spica, bluish alpha star of the constellation Virgo.

Image Credit & Copyright: Phil Hart

Hubble Watches Star Clusters on a Collision Course

Astronomers using data from NASA’s Hubble Space Telescope caught two clusters full of massive stars that may be in the early stages of merging. The 30 Doradus Nebula is 170,000 light-years from Earth. What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus has been found to be a composite of two clusters that differ in age by about one million years. 

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters. The Hubble observations, made with the Wide Field Camera 3, were taken Oct. 20-27, 2009. The blue color is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen. 

Image Credit: NASA, ESA, and E. Sabbi (ESA/STScI)

discoverynews:

Yikes! I thought that was a big old hairy spider for a moment. It’s actually a nebula. A nebula that’s hatching some baby stars. Lovely.

Dark and foreboding the nebula may look, but its wispy tendrils hold the promise of new life — newborn stars. Looking closely at the image you can see the glow of young stars shortly after pockets of gas from the nebula collapsed under gravity, sparking fusion, giving birth to new suns.

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IC 1396: Emission Nebula in Cepheus
Stunning emission nebula IC 1396 mixes glowing cosmic gas and dark dust clouds in the high and far off constellation of Cepheus. Energized by the bright, bluish central star seen here, this star forming region sprawls across hundreds of light-years — spanning over three degrees on the sky while nearly 3,000 light-years from planet Earth. Among the intriguing dark shapes within IC 1396, the winding Elephant’s Trunk nebula lies just below center. The gorgeous color view is a composition of digitized black and white photographic plates recorded through red and blue astronomical filters. The plates were taken using the Samuel Oschin Telescope, a wide-field survey instrument at Palomar Observatory, between 1989 and 1993.
Image Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator, Davide De Martin (Skyfactory)

The Bubble Nebula 

Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble’s center is a hot, O star, several hundred thousand times more luminous and around 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia. This view of the cosmic bubble is composed of narrowband and broadband image data, capturing details in the emission region while recording a natural looking field of stars.

Image Credit & Copyright: Yves Van den Broek

Messier 5

“Beautiful Nebula discovered between the Balance [Libra] & the Serpent [Serpens] …” begins the description of the 5th entry in 18th century astronomer Charles Messier’s famous catalog of nebulae and star clusters. Though it appeared to Messier to be fuzzy and round and without stars, Messier 5 (M5) is now known to be a globular star cluster, 100,000 stars or more, bound by gravity and packed into a region around 165 light-years in diameter. It lies some 25,000 light-years away. Roaming the halo of our galaxy, globular star clusters are ancient members of the Milky Way. M5 is one of the oldest globulars, its stars estimated to be nearly 13 billion years old. The beautiful star cluster is a popular target for earthbound telescopes. Even close to its dense core, the cluster’s red and blue giant stars stand out with yellowish and blue hues in this sharp color image.

Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, University of Arizona

South Pole Star Trails

No star dips below the horizon and the Sun never climbs above it in this remarkable image of 24 hour long star trails. Showing all the trails as complete circles, such an image could be achieved only from two places on planet Earth. This example was recorded during the course of May 1, 2012, the digital camera in a heated box on the roof of MAPO, the Martin A. Pomerantz Observatory at the South Pole. Directly overhead in the faint constellation Octans is the projection of Earth’s rotational axis, the South Celestial Pole, at the center of all the star trail circles. Not so well placed as Polaris and the North Celestial Pole, the star leaving the small but still relatively bright circle around the South Celestial Pole is Beta Hydri. The inverted umbrella structure on the horizon at the right of the allsky field of view is the ground shield for the SPUD telescope. A shimmering apparition of the aurora australis also visited on this 24 hour night.

Image Credit & Copyright: Robert Schwarz (South Pole Station)

Field of Stars

The Hubble Space Telescope captured a crowd of stars that looks rather like a stadium darkened before a show, lit only by the flashbulbs of the audience’s cameras. Yet the many stars of this object, known as Messier 107, are not a fleeting phenomenon, at least by human reckoning of time — these ancient stars have gleamed for many billions of years.

Messier 107 is one of more than 150 globular star clusters found around the disc of the Milky Way galaxy. These spherical collections each contain hundreds of thousands of extremely old stars and are among the oldest objects in the Milky Way. The origin of globular clusters and their impact on galactic evolution remains somewhat unclear, so astronomers continue to study them.

Messier 107 can be found in the constellation of Ophiuchus (The Serpent Bearer) and is located about 20,000 light-years from our solar system.

French astronomer Pierre Méchain first noted the object in 1782, and British astronomer William Herschel documented it independently a year later. A Canadian astronomer, Helen Sawyer Hogg, added Messier 107 to Charles Messier’s famous astronomical catalogue in 1947.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. 

Image credit: ESA/NASA

(via Field of Stars)

The Milky Way Over Monument Valley

You don’t have to be at Monument Valley to see the Milky Way arch across the sky like this — but it helps. Only at Monument Valley USA would you see a picturesque foreground that includes these iconic rock peaks called buttes. Buttes are composed of hard rock left behind after water has eroded away the surrounding soft rock. In the above image taken about two months ago, the closest butte on the left and the butte to its right are known as the Mittens, while Merrick Butte can be seen just further to the right. High overhead stretches a band of diffuse light that is the central disk of our spiral Milky Way Galaxy. The band of the Milky Way can be spotted by almost anyone on almost any clear night when far enough from a city and surrounding bright lights.

Image Credit & Copyright: Wally Pacholka (AstroPics.com, TWAN)

X-rays From A Young Supernova Remnant

More than fifty years ago, a supernova was discovered in M83, a spiral galaxy about 15 million light years from Earth. Astronomers have used NASA’s Chandra X-ray Observatory to make the first detection of X-rays emitted by the debris from this explosion.

Named SN 1957D because it was the fourth supernova to be discovered in the year 1957, it is one of only a few located outside of the Milky Way galaxy that is detectable, in both radio and optical wavelengths, decades after its explosion was observed. In 1981, astronomers saw the remnant of the exploded star in radio waves, and then in 1987 they detected the remnant at optical wavelengths, years after the light from the explosion itself became undetectable.

A relatively short observation — about 14 hours long — from NASA’s Chandra X-ray Observatory in 2000 and 2001 did not detect any X-rays from the remnant of SN 1957D. However, a much longer observation obtained in 2010 and 2011, totaling nearly 8 and 1/2 days of Chandra time, did reveal the presence of X-ray emission. The X-ray brightness in 2000 and 2001 was about the same as or lower than in this deep image.

This new Chandra image of M83 is one of the deepest X-ray observations ever made of a spiral galaxy beyond our own. This full-field view of the spiral galaxy shows the low, medium, and high-energy X-rays observed by Chandra in red, green, and blue respectively.

The new X-ray data from the remnant of SN 1957D provide important information about the nature of this explosion that astronomers think happened when a massive star ran out of fuel and collapsed. The distribution of X-rays with energy suggests that SN 1957D contains a neutron star, a rapidly spinning, dense star formed when the core of pre-supernova star collapsed. This neutron star, or pulsar, may be producing a cocoon of charged particles moving at close to the speed of light known as a pulsar wind nebula.

If this interpretation is confirmed, the pulsar in SN 1957D is observed at an age of 55 years, one of the youngest pulsars ever seen. The remnant of SN 1979C in the galaxy M100 contains another candidate for the youngest pulsar, but astronomers are still unsure whether there is a black hole or a pulsar at the center of SN 1979C.

Image Credits: X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI

(via X-rays From A Young Supernova Remnant)

Pink Aurora Over Crater Lake 

Why is this aurora strikingly pink? When photographing picturesque Crater Lake in Oregon, USA last month, the background sky lit up with auroras of unusual colors. Although much is known about the physical mechanisms that create auroras, accurately predicting the occurrence and colors of auroras remains a topic of investigation. Typically, it is known, the lowest auroras appear green. These occur at about 100 kilometers high and involve atmospheric oxygen atoms excited by fast moving plasma from space. The next highest auroras — at about 200 kilometers up — appear red, and are also emitted by resettling atmospheric oxygen. Some of the highest auroras visible — as high as 500 kilometers up — appear blue, and are caused by sunlight-scattering nitrogen ions. When looking from the ground through different layers of distant auroras, their colors can combine to produce unique and spectacular hues, in this case rare pink hues seen above. As Solar Maximum nears over the next two years, particle explosions from the Sun are sure to continue and likely to create even more memorable nighttime displays.

Image Credit & Copyright: Brad Goldpaint (Goldpaint Photography)

Dawn of the Dish 

Wandering planets Venus and Jupiter were joined by an old crescent Moon near the eastern horizon on July 15. This serene southern skyview of the much anticipated predawn conjunction includes the lovely Pleiades star cluster and bright stars Aldebaran and Betelgeuse in the celestial lineup. For help identifying the stars and constellations, just slide your cursor over the image. Of course, the radio telescope in the foreground is the Parkes 64 meter dish of New South Wales, Australia. Known for its exploration of the distant Universe at radio wavelengths, the large, steerable antenna is also famous for its superior lunar television reception. On July 21, 1969 the dish received broadcasts from the Moon that allowed denizens of planet Earth to watch the Apollo 11 moonwalk.

Image Credit & Copyright: Alex Cherney (Terrastro, TWAN)