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NASA's Great Observatories Celebrate International Year of Astronomy

A never-before-seen view of the turbulent heart of our Milky Way galaxy is being unveiled by NASA on Nov. 10. This event will commemorate the 400 years since Galileo first turned his telescope to the heavens in 1609. In celebration of this International Year of Astronomy, NASA is releasing images of the galactic center region as seen by its Great Observatories to more than 150 planetariums, museums, nature centers, libraries, and schools across the country.

The Full Story

A never-before-seen view of the turbulent heart of our Milky Way galaxy is being unveiled by NASA on Nov. 10. This event will commemorate the 400 years since Galileo first turned his telescope to the heavens in 1609.

In celebration of this International Year of Astronomy, NASA is releasing images of the galactic center region as seen by its Great Observatories to more than 150 planetariums, museums, nature centers, libraries, and schools across the country.

The sites will unveil a giant, 6-foot-by-3-foot print of the bustling hub of our galaxy that combines a near-infrared view from the Hubble Space Telescope, an infrared view from the Spitzer Space Telescope, and an X-ray view from the Chandra X-ray Observatory into one multiwavelength picture. Experts from all three observatories carefully assembled the final image from large mosaic photo surveys taken by each telescope. This composite image provides one of the most detailed views ever of our galaxy's mysterious core.

Participating institutions also will display a matched trio of Hubble, Spitzer, and Chandra images of the Milky Way's center on a second large panel measuring 3 feet by 4 feet. Each image shows the telescope's different wavelength view of the galactic center region, illustrating not only the unique science each observatory conducts, but also how far astronomy has come since Galileo.

The composite image features the spectacle of stellar evolution: from vibrant regions of star birth, to young hot stars, to old cool stars, to seething remnants of stellar death called black holes. This activity occurs against a fiery backdrop in the crowded, hostile environment of the galaxy's core, the center of which is dominated by a supermassive black hole nearly four million times more massive than our Sun. Permeating the region is a diffuse blue haze of X-ray light from gas that has been heated to millions of degrees by outflows from the supermassive black hole as well as by winds from massive stars and by stellar explosions. Infrared light reveals more than a hundred thousand stars along with glowing dust clouds that create complex structures including compact globules, long filaments, and finger-like "pillars of creation," where newborn stars are just beginning to break out of their dark, dusty cocoons.

The unveilings will take place at 152 institutions nationwide, reaching both big cities and small towns. Each institution will conduct an unveiling celebration involving the public, schools, and local media.

The Astrophysics Division of NASA's Science Mission Directorate supports the International Year of Astronomy Great Observatories image unveiling. The project is a collaboration among the Space Telescope Science Institute in Baltimore, Md., the Spitzer Science Center in Pasadena, Calif., and the Chandra X-ray Center in Cambridge, Mass.

Credits

Credit: NASA, ESA, SSC, CXC, and STScI

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Hubble Uncovers Fading Cinders of Some of Our Galaxy's Earliest Homesteaders
 
About 13 billion years ago, long before our sun formed, the construction of our Milky Way galaxy was just beginning. Young, mostly sun-like stars in the core, or central bulge, provided the building blocks for the galaxy's foundation. Many of these building-block stars have long since burned out, and are now just dying embers. But contained within these dead stars, called white dwarfs, is the early history of our galaxy, providing clues on how it came to be.
 
Finding these stellar relics, however, is a daunting task. Astronomers have had a difficult time picking out these dim objects from among the crowd of bright stars that fill the space between us and the core. Using Hubble Space Telescope images, astronomers have now conducted a "cosmic archaeological dig" of our Milky Way's heart, uncovering the blueprints of our galaxy's early construction phase. Hubble researchers have uncovered for the first time a population of ancient white dwarfs. The Hubble analysis represents the deepest, most detailed study of our galaxy's central bulge of stars.
 
The Full Story
 
Using NASA's Hubble Space Telescope to conduct a "cosmic archaeological dig" at the very heart of our Milky Way galaxy, astronomers have uncovered the blueprints of our galaxy's early construction phase.
 
Peering deep into the Milky Way's crowded central hub of stars, Hubble researchers have uncovered for the first time a population of ancient white dwarfs – smoldering remnants of once-vibrant stars that inhabited the core. Finding these relics at last can yield clues to how our galaxy was built, long before Earth and our sun formed.
 
The observations are the deepest, most detailed study of the galaxy's foundational city structure – its vast central bulge that lies in the middle of a pancake-shaped disk of stars, where our solar system dwells.
 
As with any archaeological relic, the white dwarfs contain the history of a bygone era. They contain information about the stars that existed about 12 billion years ago that burned out to form the white dwarfs. As these dying embers of once-radiant stars cool, they serve as multi-billion-year-old time pieces that tell astronomers about the Milky Way's groundbreaking years.
 
An analysis of the Hubble data supports the idea that the Milky Way's bulge formed first and that its stellar inhabitants were born very quickly – in less than roughly 2 billion years. The rest of the galaxy's sprawling disk of second- and third-generation stars grew more slowly in the suburbs, encircling the central bulge like the brim of a giant sombrero.
 
"It is important to observe the Milky Way's bulge because it is the only bulge we can study in detail," explained Annalisa Calamida of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, the science paper's lead author. "You can see bulges in distant galaxies, but you cannot resolve the very faint stars, such as the white dwarfs. The Milky Way's bulge includes almost a quarter of the galaxy's stellar mass. Characterizing the properties of the bulge stars can then provide important information to understanding the formation of the entire Milky Way galaxy and that of similar, more distant galaxies."
 
The Hubble survey also found slightly more low-mass stars in the bulge, compared to those in the galaxy's disk population. "This result suggests that the environment in the bulge may have been different than the one in the disk, resulting in a different star-formation mechanism," Calamida said.
 
The observations were so sensitive that the astronomers also used the data to pick out the feeble glow of white dwarfs. The team based its results on an analysis of 70 of the hottest white dwarfs detectable by Hubble in a small region of the bulge among tens of thousands of stars.
 
These stellar relics are small and extremely dense. They are about the size of Earth but 200,000 times denser. A teaspoon of white dwarf material would weigh about 15 tons. Their tiny stature makes them so dim that it would be as challenging as looking for the glow of a pocket flashlight located on the moon. Astronomers used the sharp Hubble images to separate the bulge stars from the myriad stars in the foreground of our galaxy's disk by tracking their movements over time. The team accomplished this task by analyzing Hubble images of the same field of 240,000 stars, taken 10 years apart. The long timespan allowed the astronomers to make very precise measurements of the stars' motion and pick out 70,000 bulge stars. The bulge's stellar inhabitants move at a different rate than stars in the disk, allowing the astronomers to identify them.
 
The region surveyed is part of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field and is located 26,000 light-years away. The unusually dust-free location on the sky offers a keyhole view into the "downtown" bulge. Hubble's Advanced Camera for Surveys made the observations in 2004 and 2011-2013.
 
"Comparing the positions of the stars from now and 10 years ago we were able to measure accurate motions of the stars," said Kailash Sahu of STScI, the study's leader. "The motions allowed us to tell if they were disk stars, bulge stars, or halo stars."
 
The astronomers identified the white dwarfs by analyzing the colors of the bulge stars and comparing them with theoretical models. The extremely hot white dwarfs appear bluer relative to sun-like stars. As white dwarfs age, they become cooler and fainter, becoming difficult even for sharp-eyed Hubble to detect.
 
"These 70 white dwarfs represent the peak of the iceberg," Sahu said. "We estimate that the total number of white dwarfs is about 100,000 in this tiny Hubble view of the bulge. Future telescopes such as NASA's James Webb Space Telescope will allow us to count almost all of the stars in the bulge down to the faintest ones, which today's telescopes, even Hubble, cannot see."
 
The team next plans to increase their sample of white dwarfs by analyzing other portions of the SWEEPS field. This should ultimately lead to a more precise estimate of the age of the galactic bulge. They might also determine if star formation processes in the bulge billions of years ago were different from what's seen in the younger disk of our galaxy.
 
The team's results appeared in the Sept. 1, 2015, issue of The Astrophysical Journal. A companion paper appeared in The Astrophysical Journal in 2014.
 
Credits
 
Credit for Hubble Images: NASA, ESA, A. Calamida and K. Sahu (STScI), and the SWEEPS Science Team
 
Credit for Ground-based Image: A. Fujii
 
 
 
White Dwarf Stars in the Milky Way Bulge 
 
About this image
 
NASA's Hubble Space Telescope has detected for the first time a population of white dwarfs embedded in the hub of our Milky Way galaxy. The Hubble images are the deepest, most detailed study of the galaxy's central bulge of stars. The smoldering remnants of once-vibrant stars can yield clues to our galaxy's early construction stages that happened long before Earth and our sun formed.
 
[Left] – This is a ground-based view of the Milky Way's central bulge, seen in the direction of the constellation Sagittarius. Giant dust clouds block most of the starlight coming from the galactic center. Hubble, however, peered through a region (marked by the arrow) called the Sagittarius Window, which offers a keyhole view into the galaxy's hub.
 
[Upper right] – This is a small section of Hubble's view of the dense collection of stars crammed together in the galactic bulge. The region surveyed is part of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field and is located 26,000 light-years away.
 
[Lower right] – Hubble uncovered extremely faint and hot white dwarfs. This is a sample of 4 out of the 70 brightest white dwarfs spied by Hubble in the Milky Way's bulge. Astronomers picked them out based on their faintness, blue-white color, and motion relative to our sun. The numbers in the inset images correspond to the white dwarfs' location in the larger Hubble view.
 
Hubble's Advanced Camera for Surveys made the observations in 2004 and 2011-2013.
 
 
Credits
 
Credit for Hubble Images: NASA, ESA, A. Calamida and K. Sahu (STScI), and the SWEEPS Science Team;
Credit for Ground-based Image: A. Fujii
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Man, Dog, Sun
 
Explanation: This was supposed to be a shot of trees in front of a setting Sun. Sometimes, though, the unexpected can be photogenic. During some planning shots, a man walking his dog unexpected crossed the ridge. The result was so striking that, after cropping, it became the main shot. The reason the Sun appears so large is that the image was taken from about a kilometer away through a telephoto lens. Scattering of blue light by the Earth's atmosphere makes the bottom of the Sun appear slightly more red that the top. Also, if you look closely at the Sun, just above the man's head, a large group of sunspots is visible. The image was taken just last week in Bad Mergentheim, Germany.
 
Image Credit & Copyright: Jens Hackmann
 
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Dark Nebula LDN 1622 and Barnard's Loop
 
Explanation: The silhouette of an intriguing dark nebula inhabits this cosmic scene. Lynds' Dark Nebula (LDN) 1622 appears below center against a faint background of glowing hydrogen gas only easily seen in long telescopic exposures of the region. LDN 1622 lies near the plane of our Milky Way Galaxy, close on the sky to Barnard's Loop - a large cloud surrounding the rich complex of emission nebulae found in the Belt and Sword of Orion. Arcs along a segment of Barnard's loop stretch across the top of the frame. But the obscuring dust of LDN 1622 is thought to be much closer than Orion's more famous nebulae, perhaps only 500 light-years away. At that distance, this 1 degree wide field of view would span less than 10 light-years.
 
Credit & Copyright: Leonardo Julio (Astronomia Pampeana)
 
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A New Angle on Two Spiral Galaxies for Hubble's 27th Birthday 
 
The Image: 
 
This animation zooms through the Virgo Cluster of nearly 2,000 galaxies into tight Hubble Space Telescope images of spiral galaxies NGC 4302 (left) and NGC 4298 (right) in visible and infrared light. Located approximately 55 million light-years away, the starry pair offers a glimpse of what our Milky Way galaxy would look like to an outside observer.
 
 
Credits: NASA, ESA, and G. Bacon, J. DePasquale, and Z. Levay (STScI) Acknowledgment: A. Fujii; Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO; B. Franke (Focal Point Observatory); and M. Mutchler (STScI)
 
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James Webb Space Telescope Mirror Seen in Full Bloom
 
It's springtime and the deployed primary mirror of NASA's James Webb Space Telescope looks like a spring flower in full bloom.
 
In this photo, NASA technicians lifted the telescope using a crane and moved it inside a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Once launched into space, the Webb telescope’s 18-segmented gold mirror is specially designed to capture infrared light from the first galaxies that formed in the early universe, and will help the telescope peer inside dust clouds where stars and planetary systems are forming today.
 
The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
 
For more information about the Webb telescope visit: www.jwst.nasa.gov or www.nasa.gov/webb
 
Image credit: NASA/Desiree Stover
 
Laura Betz
NASA Goddard Space Flight Center
 
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Stellar Ripple
 
Approximately 100 million years ago, a smaller galaxy plunged through the heart of the Cartwheel galaxy, creating ripples of brief star formation. In this image, the first ripple appears as an ultraviolet-bright blue outer ring so powerful that it may be one of the most powerful UV-emitting galaxies in the nearby universe.
 
This false-color composite image shows the Cartwheel galaxy as seen by the Galaxy Evolution Explorer (GALEX), the Hubble Space Telescope (green); the Spitzer Space Telescope (red); and the Chandra X-ray Observatory (purple).
 
Although astronomers have not identified exactly which galaxy collided with the Cartwheel, two of three candidate galaxies can be seen in this image to the bottom left of the ring, one as a neon blob and the other as a green spiral.
 
Previously, scientists believed the ring marked the outermost edge of the galaxy, but the latest GALEX observations detect a faint disk, not visible in this image, that extends to twice the diameter of the ring.
 
Image Credit: NASA/JPL-Caltech
 
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A Flood of Gas
 
A new feature in the evolution of galaxies has been captured in this image of galactic interactions. The two galaxies seen here -- NGC 3226 at the top, NGC 3227 at the bottom -- are awash in the remains of a departed third galaxy, cannibalized by the gravity of the surviving galaxies. The surge of warm gas flowing into NGC 3226, seen as a blue filament, appears to be shutting down this galaxy's star formation, disrupting the cool gas needed to make fresh stars.
 
The findings come courtesy of the European Space Agency's Herschel space observatory, in which NASA played a key role, and NASA's Spitzer and Hubble space telescopes.
 
Adding material to galaxies often rejuvenates them, triggering new rounds of star birth as gas and dust gel together. Yet data from the three telescopes all indicate that NGC 3226 has a very low rate of star formation.
 
In this instance, material falling into NGC 3226 is heating up as it collides with other galactic gas and dust, quenching star formation instead of fueling it. As this warm gas chills out in the future, though, NGC 3226 should get a second wind in its stalled-out production of new stars.
 
The gray scale in this image shows optical starlight captured by the MegaCam instrument at the Canada France Hawaii Telescope (CFHT) telescope on Mauna Kea in Hawaii, and reveals loops of stars flung about by the galactic cannibalism. The blue color represents cool hydrogen gas seen in radio waves by the Very Large Array near Socorro, New Mexico. The big plume of gas above NGC 3226 is being drawn into the galaxy by its gravity. The red color shows infrared light emissions, captured by Spitzer, from warm gas and dust at the tip of the plume's infalling stream of material into NGC 3226, as well as from features within NGC 3227.
 
Other Spitzer observations reveal a disk of warm molecular gas at the core of NGC 3226, fed by the plume. Herschel observations, not shown in the image, were used to create a galactic star-formation model, which confirms NGC 3226's very low star-formation rate.
 
The interacting galaxies are located 49 million light-years away in the constellation Leo.
 
Visible starlight at wavelengths of 550 to 700 nanometers is shown in gray scale. The infrared glow of dust at 8 microns, as seen by Spitzer, is displayed in red, while the radio glow of hydrogen gas at 21 centimeters, from the VLA, is shown in blue.
 
Credit: NASA/CFHT/NRAO/JPL-Caltech/Duc/Cuillandre
 
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NGC 4696: The Arrhythmic Beating of a Black Hole Heart
 
A black hole has been "beating" about every 5 to 10 million years, pumping material and energy into its environment.
 
This black hole is at the center of a large elliptical galaxy located within the core of the Centaurus Cluster of galaxies.
 
Data from Chandra and other telescopes show evidence for repeated bursts, or eruptions, from the black hole.
 
These bursts created cavities within the hot, X-ray emitting gas that pervades the cluster.
 
 
At the center of the Centaurus galaxy cluster, there is a large elliptical galaxy called NGC 4696. Deeper still, there is a supermassive black hole buried within the core of this galaxy.
 
New data from NASA's Chandra X-ray Observatory and other telescopes has revealed details about this giant black hole, located some 145 million light years from Earth. Although the black hole itself is undetected, astronomers are learning about the impact it has on the galaxy it inhabits and the larger cluster around it.
 
In some ways, this black hole resembles a beating heart that pumps blood outward into the body via the arteries. Likewise, a black hole can inject material and energy into its host galaxy and beyond.
 
By examining the details of the X-ray data from Chandra, scientists have found evidence for repeated bursts of energetic particles in jets generated by the supermassive black hole at the center of NGC 4696. These bursts create vast cavities in the hot gas that fills the space between the galaxies in the cluster. The bursts also create shock waves, akin to sonic booms produced by high-speed airplanes, which travel tens of thousands of light years across the cluster.
 
This composite image contains X-ray data from Chandra (red) that reveals the hot gas in the cluster, and radio data from the NSF's Karl G. Jansky Very Large Array (blue) that shows high-energy particles produced by the black hole-powered jets. Visible light data from the Hubble Space Telescope (green) show galaxies in the cluster as well as galaxies and stars outside the cluster.
 
Astronomers employed special processing to the X-ray data (shown above) to emphasize nine cavities visible in the hot gas. These cavities are labeled A through I in an additional image, and the location of the black hole is labeled with a cross. The cavities that formed most recently are located nearest to the black hole, in particular the ones labeled A and B.
 
The researchers estimate that these black hole bursts, or "beats", have occurred every five to ten million years. Besides the vastly differing time scales, these beats also differ from typical human heartbeats in not occurring at particularly regular intervals.
 
A different type of processing of the X-ray data reveals a sequence of curved and approximately equally spaced features in the hot gas. These may be caused by sound waves generated by the black hole's repeated bursts. In a galaxy cluster, the hot gas that fills the cluster enables sound waves — albeit at frequencies far too low for the human hear to detect — to propagate. (Note that both images showing the labeled cavities and this image are rotated slightly clockwise to the main composite.)
 
The features in the Centaurus Cluster are similar to the ripples seen in the Perseus cluster of galaxies. The pitch of the sound in Centaurus is extremely deep, corresponding to a discordant sound about 56 octaves below the notes near middle C. This corresponds to a slightly higher (by about one octave) pitch than the sound in Perseus. Alternative explanations for these curved features include the effects of turbulence or magnetic fields.
 
The black hole bursts also appear to have lifted up gas that has been enriched in elements generated in supernova explosions. The authors of the study of the Centaurus cluster created a map (shown above) showing the density of elements heavier than hydrogen and helium. The brighter colors in the map show regions with the highest density of heavy elements and the darker colors show regions with a lower density of heavy elements. Therefore, regions with the highest density of heavy elements are located to the right of the black hole. A lower density of heavy elements near the black hole is consistent with the idea that enriched gas has been lifted out of the cluster's center by bursting activity associated with the black hole. The energy produced by the black hole is also able to prevent the huge reservoir of hot gas from cooling. This has prevented large numbers of stars from forming in the gas.
 
A paper describing these results was published in the March 21st 2016 issue of the Monthly Notices of the Royal Astronomical Society and is available online. The first author is Jeremy Sanders from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.
 
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.
 
Credit X-ray: NASA/CXC/MPE/J.Sanders et al.; Optical: NASA/STScI; Radio: NSF/NRAO/VLA
 
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Spiral Galaxy Pair NGC 4302 and NGC 4298
 
About this image
 
In celebration of the 27th anniversary of the launch of NASA’s Hubble Space Telescope on April 24, 1990, astronomers used the legendary telescope to take a portrait of a stunning pair of spiral galaxies. This starry pair offers a glimpse of what our Milky Way galaxy would look like to an outside observer.
 
The edge-on galaxy is called NGC 4302, and the tilted galaxy is NGC 4298. These galaxies look quite different because we see them angled at different positions on the sky. They are actually very similar in terms of their structure and contents.
 
From our view on Earth, researchers report an inclination of 90 degrees for NGC 4302, which is exactly edge on. NGC 4298 is tilted 70 degrees.
 
In NGC 4298, the telltale, pinwheel-like structure is visible, but it’s not as prominent as in some other spiral galaxies. In the edge-on NGC 4302, dust in the disk is silhouetted against rich lanes of stars. Absorption by dust makes the galaxy appear darker and redder than its companion. A large blue patch appears to be a giant region of recent star formation.
 
Both galaxies are approximately 55 million light-years away. They reside in the constellation Coma Berenices in the Virgo Cluster of nearly 2,000 galaxies. Both were discovered in 1784 by astronomer William Herschel. Such objects were first simply called “spiral nebulas,” because it wasn’t known how far away they were. In the early 20th century, Edwin Hubble discovered that galaxies are other island cities of stars far outside our Milky Way.
 
A typical spiral galaxy has arms of young stars that wind outward from its center. The bright arms are regions of intense star formation. Such galaxies have a central bulge and are surrounded by a faint halo of stars. Many spiral galaxies also have bars that extend from the central bulge to the arms.
 
The edge-on NGC 4302 is about 87,000 light-years in diameter, which is about 60 percent the size of the Milky Way. It is about 110 billion solar masses, approximately one-tenth of the Milky Way’s mass.
 
The tilted NGC 4298 is about 45,000 light-years in diameter, about one third the size of the Milky Way. At 17 billion solar masses, it is less than 2 percent of the Milky Way galaxy’s 1 trillion solar masses.
 
The Hubble observations were taken between January 2 and January 22, 2017 with the Wide Field Camera 3 (WFC3) instrument in three visible light bands.
 
The Hubble Space Telescope was launched aboard the Space Shuttle Discovery on April 24, 1990 and deployed into low-Earth orbit the next day. From its perch high above the distorting effects of Earth’s atmosphere, Hubble observes the universe i near-ultraviolet, visible, and near-infrared light. Over the past 27 years, the space telescope’s breakthrough discoveries have revolutionized the fields of astronomy and astrophysics.
 
 
Credits
NASA, ESA, and M. Mutchler (STScI)
 
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