Suðurland, Iceland
Image Credit: Árni Sæberg
May 20, 2017
Galaxy Cluster MACS J0717.5+3745
This is a NASA/ESA Hubble Space Telescope image of the galaxy cluster MACS J0717.5+3745. Shown in blue on the image is a map of the dark matter found within the cluster. This cluster was part of a study of 72 galaxy cluster collisions which determined that dark matter interacts with other dark matter even less than previously thought.
Image Credit: NASA, ESA
Explanation from: http://spacetelescope.org/images/heic1506f/
Cassiopeia A
Astronomers using NASA's infrared Spitzer Space Telescope have discovered that an exploded star, named Cassiopeia A, blew up in a somewhat orderly fashion, retaining much of its original onion-like layering.
"Spitzer has essentially found key missing pieces of the Cassiopeia A puzzle," said Jessica Ennis of the University of Minnesota, Minneapolis.
"We've found new bits of the 'onion' layers that had not been seen before," said Dr. Lawrence Rudnick, also of the University of Minnesota, and principal investigator of the research. "This tells us that the star's explosion was not chaotic enough to stir its remains into one big pile of mush."
Cassiopeia A, or Cas A for short, is what is known as a supernova remnant. The original star, about 15 to 20 times more massive than our sun, died in a cataclysmic "supernova" explosion relatively recently in our own Milky Way galaxy. Like all mature massive stars, the Cas A star was once neat and tidy, consisting of concentric shells made up of various elements. The star's outer skin consisted of lighter elements, such as hydrogen; its middle layers were lined with heavier elements like neon; and its core was stacked with the heaviest elements, such as iron.
Until now, scientists were not exactly sure what happened to the Cas A star when it ripped apart. One possibility is that the star exploded in a more or less uniform fashion, flinging its layers out in successive order. If this were the case, then those layers should be preserved in the expanding debris. Previous observations revealed portions of some of these layers, but there were mysterious gaps.
Spitzer was able to solve the riddle. It turns out that parts of the Cas A star had not been shot out as fast as others when the star exploded. Imagine an onion blasting apart with some layered chunks cracking off and zooming away, and other chunks from a different part of the onion shooting off at slightly slower speeds.
"Now we can better reconstruct how the star exploded," said Dr. William Reach of NASA's Spitzer Science Center, Pasadena, Calif. "It seems that most of the star's original layers flew outward in successive order, but at different average speeds depending on where they started."
How did Spitzer find the missing puzzle pieces? As the star's layers whiz outward, they are ramming, one by one, into a shock wave from the explosion and heating up. Material that hit the shock wave sooner has had more time to heat up to temperatures that radiate X-ray and visible light. Material that is just now hitting the shock wave is cooler and glowing with infrared light. Consequently, previous X-ray and visible-light observations identified hot, deep-layer material that had been flung out quickly, but not the cooler missing chunks that lagged behind. Spitzer's infrared detectors were able to find the missing chunks -- gas and dust consisting of the middle-layer elements neon, oxygen and aluminum.
Cassiopeia A is the ideal target for studying the anatomy of a supernova explosion. Because it is young and relatively close to our solar system, it is undergoing its final death throes right in front of the watchful eyes of various telescopes. In a few hundred years or so, Cas A's scattered remains will have completely mixed together, forever erasing important clues about how the star lived and died.
Image Credit: NASA/JPL-Caltech/L. Rudnick (University of Minnesota)
Explanation from: http://www.spitzer.caltech.edu/news/245-ssc2006-19-NASA-s-Spitzer-Peels-Back-Layers-of-Star-s-Explosion
Ara Ararauna
The blue-and-yellow macaw (Ara ararauna), also known as the blue-and-gold macaw, is a large South American parrot with blue top parts and yellow under parts. It is a member of the large group of neotropical parrots known as macaws. It inhabits forest (especially varzea, but also in open sections of terra firme or unflooded forest) and woodland of tropical South America. They are popular in aviculture because of their striking color, ability to talk, ready availability in the marketplace, and close bonding to humans.
These birds can reach a length of 76–86 cm (30–34 in) and weigh 0.900–1.5 kg (2–3 lb), making them some of the larger members of their family. They are vivid in appearance with blue wings and tail, dark-blue chin, golden under parts, and a green forehead. Their beaks are black. The naked face is white, turning pink in excited birds, and lined with small, black feathers. Blue-and-yellow macaws live from 30 to 35 years in the wild.
Little variation in plumage is seen across the range. Some birds have a more orange or "butterscotch" underside color, particularly on the breast. This was often seen in Trinidad birds and others of the Caribbean area. The blue-and-yellow macaw uses its powerful beak for breaking nutshells, and for climbing up and hanging from trees.
This species occurs in Venezuela, Peru, Brazil, Bolivia, and Paraguay. The range extends slightly into Central America, where it is restricted to Panama. The species' range formerly included Trinidad, but it became extinct there by 1970 as a result of human activities. Between 1999 and 2003, wild-caught blue-and-gold macaws were translocated from Guyana to Trinidad, in an attempt to re-establish the species in a protected area around Nariva swamp. A small breeding population descended from introduced birds is found in Puerto Rico, and another has inhabited Miami-Dade County, Florida, since the mid-1980s.
Explanation from: https://en.wikipedia.org/wiki/Blue-and-yellow_macaw
Two Solar Prominences
At the edge of the Sun, a large prominence and a small prominence began to shift, turn and fall apart in less than one day (May 8-9, 2017). Prominences are notoriously unstable. Competing magnetic forces pulled the plasma back and forth until they dissipated. The images were taken in a wavelength of extreme ultraviolet light.
Image Credit: NASA/GSFC/Solar Dynamics Observatory
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21634
Exoplanet HD 189733b
This illustration shows HD 189733b, a huge gas giant that orbits very close to its host star HD 189733. The planet's atmosphere is scorching with a temperature of over 1000 degrees Celsius, and it rains glass, sideways, in howling 7000 kilometre-per-hour winds.
At a distance of 63 light-years from us, this turbulent alien world is one of the nearest exoplanets to Earth that can be seen crossing the face of its star. By observing this planet before, during, and after it disappeared behind its host star during orbit, astronomers were able to deduce that HD 189733b is a deep, azure blue — reminiscent of Earth's colour as seen from space.
Image Credit: NASA, ESA, M. Kornmesser
Explanation from: https://www.spacetelescope.org/images/heic1312a/
May 19, 2017
Mount Tavurvur Volcano Eruption
Rabaul, New Britain, Papua New Guinea
August 29, 2014
Image Credit: Oliver Bluett/AFP/Getty Images
Andromeda Galaxy
This mosaic of the Andromeda spiral galaxy highlights explosive stars in its interior, and cooler, dusty stars forming in its many rings. The image is a combination of observations from the Herschel Space Observatory taken in infrared light (seen in orange hues), and the XMM-Newton telescope captured in X-rays (seen in blues). NASA plays a role in both of these European Space Agency-led missions.
Herschel provides a detailed look at the cool clouds of star birth that line the galaxy's five concentric rings. Massive young stars are heating blankets of dust that surround them, causing them to glow in the longer-wavelength infrared light, known as far-infrared, that Herschel sees.
In contrast, XMM-Newton is capturing what happens at the end of the lives of massive stars. It shows the high-energy X-rays that come from, among other objects, supernova explosions and massive dead stars rotating around companions. These X-ray sources are clustered in the center of the galaxy, where the most massive stars tend to form.
Andromeda is our Milky Way galaxy's nearest large neighbor. It is located about 2.5 million light-years away and holds up to an estimated trillion stars. Our Milky Way is thought to contain about 200 billion to 400 billion stars.
Image Credit: ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent; X-ray: ESA/XMM Newton/EPIC/W. Pietsch, MPE
Explanation from: https://www.nasa.gov/mission_pages/herschel/pia13771.html
Eta Carinae Nebula
Eta Carinae is one of the most massive and brightest stars in the Milky Way. Compared to our own Sun, it is about 100 times as massive and a million times as bright. This famed variable hypergiant star (upper center) is surrounded by the Carina Nebula. In this composite image spanning the visible and infrared parts of the spectrum, areas that appear blue are not obscured by dust, while areas that appear red are hidden behind dark clouds of dust in visible light. A study combining X-ray and Infrared observations has revealed a new population of massive stars lurking in regions of the nebula that are highly obscured by dust. Adding these new massive stars to the known massive stars suggests that the Carina Nebula will produce twice as many supernova explosions as previously supposed.
Visible light in the blue part of the spectrum from the Digital Sky Survey is represented as blue, near infrared light with a wavelength of 2.2 microns from the Two Micron All Sky Survey (2MASS) is green, and infrared observations from the Infrared Array Camera on NASA's Spitzer Space telescope at 3.6 microns is red.
Image Credit: NASA/JPL-Caltech/M. Povich (Penn State Univ.)
Explanation from: http://www.spitzer.caltech.edu/images/3599-sig11-006-New-View-of-the-Great-Nebula-in-Carina
May 18, 2017
Puyehue-Cordón Caulle Volcano Eruption
Osorno, Los Lagos, Chile
Image Credit & Copyright: Francisco Negroni
Jupiter's Little Red Spot
This view of Jupiter, taken by the JunoCam imager of NASA's Juno spacecraft, highlights Oval BA -- a massive storm known as the Little Red Spot. Despite its unofficial name, the Little Red Spot is about as wide as Earth. The storm reached its current size when three smaller spots collided and merged in the year 2000. The Great Red Spot, which is about twice as wide as the Little Red Spot, may have formed from the same process centuries ago.
Juno acquired this image on February 2, 2017, at 6:13 a.m. PDT (9:13 a.m. EDT), as the spacecraft performed a close flyby of Jupiter. When the image was taken, the spacecraft was about 9,000 miles (14,500 kilometers) from the planet.
Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Bjorn Jonsson
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21391
Star IRAS 13481-6124
This star-forming region, captured by NASA's Spitzer Space Telescope, is dominated by the bright, young star IRAS 13481-6124 (upper left), which is about twenty times the mass of our Sun and five times its radius, and is surrounded by its pre-natal cocoon. It is the first massive baby star for which astronomers could obtain a detailed look at the dusty disk closely encircling it. The research provides direct evidence that massive stars do form in the same way as their smaller brethren.
From this archival Spitzer image, as well as from observations done with the APEX 12-metre sub-millimetre telescope, astronomers discovered the presence of a jet, hinting at the presence of a disk. This was then confirmed by observations made with the European Southern Observatory Very Large Telescope Interferometer.
This picture was taken with Spitzer's infrared array camera. It is a four-color composite, in which light with a wavelength of 3.6 microns is blue; 4.5-micron light is green; 5.8-micron light is orange; and 8-micron light is red. Dust appears red-orange and most stars are blue, though ones deeply embedded within dust (like IRAS 13481-6124) take on greenish-yellow tints.
Image Credit: ESO/NASA/JPL-Caltech/S. Kraus
Explanation from: http://www.spitzer.caltech.edu/images/3206-sig10-011-A-Massive-Star-and-Its-Cradle
May 17, 2017
Copahue Volcano Eruption
Caviahue, Neuquen Province, Argentina
December 22, 2012
Image Credit: AFP/Getty Images
Super Star Cluster Westerlund 1
This new picture from the VLT Survey Telescope (VST) at ESO's Paranal Observatory shows the remarkable super star cluster Westerlund 1. This exceptionally bright cluster lies about 16 000 light-years from Earth in the southern constellation of Ara (The Altar). It contains hundreds of very massive and brilliant stars, all of which are just a few million years old — babies by stellar standards. But our view of this cluster is hampered by gas and dust that prevents most of the visible light from the cluster's stars from getting to Earth.
Now, astronomers studying images of Westerlund 1 from a new survey of the southern skies have spotted something unexpected in this cluster. Around one of the stars — known as W26, a red supergiant and possibly the biggest star known— they have discovered clouds of glowing hydrogen gas, shown as green features in this new image.
Such glowing clouds around massive stars are very rare, and are even rarer around a red supergiant— this is the first ionised nebula discovered around such a star. W26 itself would be too cool to make the gas glow; the astronomers speculate that the source of the ionising radiation may be either hot blue stars elsewhere in the cluster, or possibly a fainter, but much hotter, companion star to W26.
W26 will eventually explode as a supernova. The nebula that surrounds it is very similar to the nebula surrounding SN1987A, the remnants of a star that went supernova in 1987. SN1987A was the closest observed supernova to Earth since 1604, and as such it gave astronomers a chance to explore the properties of these explosions. Studying objects like this new nebula around W26 will help astronomers to understand the mass loss processes around these massive stars, which eventually lead to their explosive demise.
Image Credit: ESO/VPHAS+ Survey/N. Wright
Explanation from: https://www.eso.org/public/images/potw1341a/
The Tarantula Nebula
This composite of 30 Doradus, aka the Tarantula Nebula, contains data from Chandra (blue), Hubble (green), and Spitzer (red). Located in the Large Magellanic Cloud, the Tarantula Nebula is one of the largest star-forming regions close to the Milky Way. Chandra's X-rays detect gas that has been heated to millions of degrees by stellar winds and supernovas. This high-energy stellar activity creates shock fronts, which are similar to sonic booms. Hubble reveals the light from massive stars at various stages of star birth, while Spitzer shows where the relatively cooler gas and dust lie.
Image Credit: X-ray: NASA/CXC/PSU/L.Townsley et al.; Optical: NASA/STScI; Infrared: NASA/JPL/PSU/L.Townsley et al.
Explanation from: http://www.spitzer.caltech.edu/images/5130-sig12-004-A-New-View-of-the-Tarantula-Nebula
May 16, 2017
Landslides on Ceres
NASA's Dawn spacecraft has revealed many landslides on Ceres, which researchers interpret to have been shaped by a significant amount of water ice. A 2017 study in the journal Nature Geoscience classifies three types of these debris flows.
Image 1 shows an example of "Type I" flow features, which are relatively round and large, have thick "toes" at their ends. They look similar to rock glaciers and icy landslides on Earth. Type I landslides are mostly found at high latitudes, which is also where the most ice is thought to reside near Ceres' surface.
Image 2 shows an example of a "Type II" flow feature. Type II features are often thinner and longer than Type I, and are the most common type of landslide on Ceres. They appear more like the avalanches seen on Earth.
Image 3 shows an example of a "Type III" flow feature at Datan Crater. The study authors interpret Ceres' Type III landslides to involve melted ice, although scientists do not know if they actually contain liquid water. The authors think Type III landslides are related to impact craters, and may have formed during impact events into the ice on Ceres. The features resemble fluid material ejected from craters in the icy regions of Mars and Jupiter's moon Ganymede.
Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21471
Exoplanet HD 80606b
The turbulent atmosphere of a hot, gaseous planet known as HD 80606b is shown in this simulation based on data from NASA's Spitzer Space Telescope. The planet spends most of its time far away from its star, but every 111 days, it swings extremely close to the star, experiencing a massive burst of heat. Spitzer measured the whole heating cycle of this planet, determining its coolest (less than 400 degrees Fahrenheit) and hottest (2,000 degrees Fahrenheit) temperatures.
Image Credit: NASA/JPL-CalTech
Explanation from: https://www.nasa.gov/image-feature/jpl/simulated-atmosphere-of-a-hot-gas-giant
Protoplanetary Disk HH 212
This intriguing image may look like a collection of coloured blobs, but it is actually a high-resolution snapshot of a newborn star enshrouded in dust. Just 1300 light-years away in the Orion Nebula, the star, named HH 212, is remarkably young. The average lifespan of such a low-mass star is around 100 billion years, but this star is only 40 000 years old — truly an infant in stellar terms.
In the cores of the vast molecular clouds in star formation regions, an ongoing battle rages; gravity versus the pressure of gas and dust. If gravity wins, it forces the gas and dust to collapse into a hot dense core that eventually ignites — forming a protostar. All the leftover gas and dust form a spinning disc around this baby star, and in many star systems they eventually coalesce to make planets. Such very young protostellar discs have been hard to image because of their relatively small size, but now the exceedingly high resolution of the Atacama Large Millimeter/submillimeter Array (ALMA) makes it possible to understand the intricate details of star and planet formation.
A closer look at HH 212 reveals a prominent, cool, dark dust lane running through the disc, sandwiched between two brighter regions that are heated by the protostar. The result resembles a cosmic “hamburger”. This is the very first time astronomers have spotted such a dust lane in the earliest phases of star formation, and so it may provide clues as to how planetary systems are born.
Image Credit: ALMA (ESO/NAOJ/NRAO)/ Lee et al.
Explanation from: https://www.eso.org/public/images/potw1720a/
May 15, 2017
Spiral Galaxy NGC 1097
Two galaxies, about 50 million light-years away, are locked in a galactic embrace — literally. The Seyfert galaxy NGC 1097, in the constellation of Fornax (The Furnace), is seen in this image taken with the VIMOS instrument on ESO’s Very Large Telescope (VLT). A comparatively tiny elliptical companion galaxy, NGC 1097A, is also visible in the top left. There is evidence that NGC 1097 and NGC 1097A have been interacting in the recent past.
Although NGC 1097 seems to be wrapping its companion in its spiral arms, this is no gentle motherly giant. The larger galaxy also has four faint jets — too extended and faint to be seen in this image — that emerge from its centre, forming an X-shaped pattern, and which are the longest visible-wavelength jets of any known galaxy. The jets are thought to be the remnants of a dwarf galaxy that was disrupted and cannibalised by the much larger NGC 1097 up to a few billion years ago.
These unusual jets are not the galaxy’s only intriguing feature. As previously mentioned, NGC 1097 is a Seyfert galaxy, meaning that it contains a supermassive black hole in its centre. However, the core of NGC 1097 is relatively faint, suggesting that the central black hole is not currently swallowing large quantities of gas and stars. Instead, the most striking feature of the galaxy’s centre is the ring of bright knots surrounding the nucleus. These knots are thought to be large bubbles of glowing hydrogen gas about 750–2500 light-years across, ionised by the intense ultraviolet light of young stars, and they indicate that the ring is a site of vigorous star formation
With this distinctive central star-forming ring, and the addition of numerous bluish clusters of hot, young stars dotted through its spiral arms, NGC 1097 makes a stunning visual object.
The data were originally taken in 2004 with the VIMOS instrument on the VLT, and additional colour information from an image taken by amateur astronomer Robert Gendler has been superimposed. The VLT data were taken through three visible-light filters: R (at a wavelength of 652 nanometres, and shown here in red), V (a wavelength of 540 nanometres, shown in green), and B (456 nanometres, shown in blue). The image covers a region of approximately 7.7 x 6.6 arcminutes on the sky.
Image Credit: ESO/R. Gendler
Explanation from: https://www.eso.org/public/images/potw1128a/
