Protostar IRAS 20324+4057

This light-year-long knot of interstellar gas and dust resembles a caterpillar on its way to a feast. But the meat of the story is not only what this cosmic caterpillar eats for lunch, but also what's eating it. Harsh winds from extremely bright stars located 15 light-years away from the knot towards the right edge of the image, are blasting ultraviolet radiation at this "wanna-be" star and sculpting the gas and dust into its long shape.

The caterpillar-shaped knot, called IRAS 20324+4057, is a protostar in a very early evolutionary stage. It is still in the process of collecting material from an envelope of gas surrounding it.

This image is a composite of Hubble Advanced Camera for Surveys (ACS) data taken in green and infrared light in 2006, and ground-based hydrogen data from the Isaac Newton Telescope in 2003, as part of the IPHAS H-alpha survey. The object lies 4500 light-years away in the constellation of Cygnus (The Swan).

Image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and IPHAS

Sagittarius A*

Sagittarius A*: The supermassive black hole located 26,000 light years from Earth in the center of the Milky Way.

One of the biggest observing campaigns ever performed by Chandra has provided new understanding into why gas near the giant black hole at the center of the Milky Way is extraordinarily faint in X-rays. The large image contains X-rays from Chandra (blue) and infrared emission from the Hubble (red and yellow). The inset shows a close-up of Sgr A* in X-rays only, covering a region half a light year wide. The diffuse X-ray emission is from hot gas captured by the black hole and being pulled inwards. The new results indicate that less than 1% of the material that is initially within the black hole’s gravitational grasp reaches the event horizon, or, point of no return.

Scale: Wide-field: 1 arcmin across (about 7.5 light years); Close-up: about 4 arcsec (about 0.5 light year).

Image credit: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI

Note: For more information, see Sagittarius A*: NASA'S Chandra Catches Our Galaxy's Giant Black Hole Rejecting Food.

The Life Cycle of a Sun-Like Star

This image tracks the life of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant star on the right. On the left the star is seen as a protostar, embedded within a dusty disc of material as it forms. It later becomes a star like our Sun. After spending the majority of its life in this stage, the star's core begins to gradually heat up, the star expands and becomes redder until it transforms into a red giant.

Following this stage, the star will push its outer layers into the surrounding space to form an object known as a planetary nebula, while the core of the star itself will cool into a small, dense remnant called a white dwarf star.

Marked on the lower timeline are where our Sun and solar twins 18 Sco and HIP 102152 are in this life cycle. The Sun is 4.6 billion years old and 18 Sco is 2.9 billion years old, while the oldest solar twin is some 8.2 billion years old — the oldest solar twin ever identified. By studying HIP 102152, we can get a glimpse of what the future holds for our Sun.

This image is illustrative; the ages, sizes, and colors are approximate (not to scale). The protostar stage, on the far left of this image, can be some 2000 times larger than our Sun. The red giant stage, on the far right of this image, can be some 100 times larger than the Sun.

Illustration credit: ESO/M. Kornmesser

Note: For more information, see Oldest Solar Twin Identified.

Orion A

The Orion A star-formation cloud seen by ESA’s Herschel space observatory. The Orion Nebula is located within the central bright region of this scene, where massive star formation is most intense. Cooler gas and dust is seen in red and yellow, with point-like sources the seeds of new stars.

The image is a composite of the wavelengths of 70 microns (blue), 160 microns (green) and 250 microns (red) and spans about 1.3 x 2.4 degrees. North is up and east is to the left.

Image credit: ESA/Herschel/Ph. André, D. Polychroni, A. Roy, V. Könyves, N. Schneider for the Gould Belt survey Key Program

Carina Nebula

Massive stars can wreak havoc on their surroundings, as can be seen in this new view of the Carina nebula from NASA's Spitzer Space Telescope. The bright star at the center of the nebula is Eta Carinae, one of the most massive stars in the galaxy. Its blinding glare is sculpting and destroying the surrounding nebula.

Eta Carinae is a true giant of a star. It is around 100 times the mass of our sun and is burning its nuclear fuel so quickly that it is at least one million times brighter than the sun. It has brightened and faded over the years, and some astronomers think it could explode as a supernova in the not-too-distant future.

Such a tremendous outflow of energy comes at a great cost to the surrounding nebula. The infrared light from the star destroys particles of dust, sculpting cavities and leaving pillars of denser material that point back to the star. Spitzer's infrared vision lets us see the dust, shown in red, as well as clouds of hot, glowing gas that appear green.

Spitzer released an image of a small part of this nebula in 2005. Subsequent observations greatly expanded our view of the entire region, and the data were combined and reprocessed as part of the extended Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) project.

The infrared images were captured with the Spitzer's infrared array camera. The pictures are three-channel composites, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), and 8.0 microns (red).

Image credit: NASA/JPL-Caltech

NGC 253

The spectacular swirling arms and central bar of the Sculptor galaxy are revealed in this new view from NASA's Spitzer Space Telescope. This image is an infrared composite combining data from two of Spitzer's detectors taken during its early cold, or cryogenic, mission.

Also known as NGC 253, the Sculptor galaxy is part of a cluster of galaxies visible to observers in the Southern hemisphere. It is known as a starburst galaxy for the extraordinarily strong star formation in its nucleus. This activity warms the surrounding dust clouds, causing the brilliant yellow-red glow in the center of this infrared image.

Figure 1 is split into two constituent parts on the right. On the top is a blue glow primarily from the light of stars as seen at the shorter wavelengths of infrared light. In this view, the disk, spiral arms and central bar are easy to see. The lower right image shows the glow of dust at longer infrared wavelengths in green and red. Regions of star formation glow especially bright at the longest wavelengths (red).

While Spitzer is now operating without any onboard cryogen, it can still operate its shorter-wavelength detectors to produce images equivalent to the star map on the upper right. Spitzer continues to be a valuable tool for studying the infrared properties of galaxies near and far.

Infrared light with wavelengths of 3.6 and 4.5 microns is shown as blue/cyan. Eight-micron light is rendered in green, and 24-micron emission is red.

Image credit: NASA/JPL-Caltech

Note: For more information, see NASA's Spitzer Telescope Celebrates 10 Years in Space.

HH 46/47

This unprecedented image of Herbig-Haro object HH 46/47 combines radio observations acquired with the Atacama Large Millimeter/submillimeter Array (ALMA) with much shorter wavelength visible light observations from ESO’s New Technology Telescope (NTT). The ALMA observations (orange and green, lower right) of the newborn star reveal a large energetic jet moving away from us, which in the visible is hidden by dust and gas. To the left (in pink and purple) the visible part of the jet is seen, streaming partly towards us.

Image credit: ESO/ALMA (ESO/NAOJ/NRAO)/H. Arce. Acknowledgements: Bo Reipurth

Note: For more information, see ALMA Takes Close Look at Drama of Starbirth.

Asteroid 2005 WK4

This collage of radar images of near-Earth asteroid 2005 WK4 was collected by NASA scientists using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California, on August 8, 2013. The asteroid is between 660 and 980 feet (200 and 300 meters) in diameter; it has a rounded and slightly asymmetric shape. As it rotates a number of features are evident that suggest the presence of some flat regions and a bulge near the equator. The data were obtained between 12:40 and 7:10 a.m. PDT (3:40 and 10:10 a.m. EDT). At the time of the observations, the asteroid's distance was about 1.93 million miles (3.1 million kilometers), which is 8.2 lunar distances away. The data were obtained over an interval of 6.5 hours as the asteroid completed about 2.4 rotations. The resolution is 12 feet (3.75 meters) per pixel.

Image credit: NASA/JPL-Caltech/GSSR

Note: For more information, see Radar Images of Asteroid 2005 WK4.

ESO 489-056

Astronomical pictures sometimes deceive us with tricks of perspective. Right in the center of this image, two spiral galaxies appear to be suffering a spectacular collision, with a host of stars appearing to flee the scene of the crash in a chaotic stampede.

However, this is just a trick of perspective. It is true that two spiral galaxies are colliding, but they are millions of light-years away, far beyond the cloud of blue and red stars near the merging spiral. This sprinkling of stars is actually an isolated, irregular dwarf galaxy named ESO 489-056. The dwarf galaxy is actually much more distant than many bright stars in the foreground of the image, which are located much closer to us, in the Milky Way.

ESO 489-056 is located 16 million light-years from Earth in the constellation of Canis Major (The Greater Dog), in our local Universe. It is composed of a few billion red and blue stars — a very small number when compared to galaxies like the Milky Way, which is estimated to contain around 200 to 400 billion stars, or the Andromeda Galaxy, which contains a mind-boggling one trillion.

Photo credit: ESA/Hubble & NASA

Magnetar SGR 0418+5729 With a Magnetic Loop

This image shows an artist's impression of the magnetar SGR 0418+5729.

Magnetars are peculiar pulsars – the spinning remnants of massive stars – that are characterised by unusually intense magnetic fields. Astronomers discovered them through their exceptional behavior at X-ray wavelengths, including sudden outbursts of radiation and occasional giant flares. These peculiar features of magnetars are caused by their extremely strong magnetic fields, which range between 1014 and 1015 Gauss (G) and are hundreds or thousands of times more intense than those of regular pulsars.

Since it was discovered in 2009, SGR 0418+5729 has been puzzling astronomers. Its dipolar magnetic field – the most direct manifestation of a magnetar's average magnetic field, which can be estimated from its spin-down rate – is about two orders of magnitude lower than other magnetars. Astronomers believed that this magnetar concealed, in its interior, a very strong magnetic field. A study based on data from ESA's XMM-Newton X-ray Observatory has found evidence to confirm this, revealing that the magnetar's internal field may even exceed 1015 G, removing any lingering doubts about the object's true identity.

The strong internal magnetic field of this magnetar reveals itself only in a small feature emerging from its surface, where protons absorb some of the X-rays emitted by the magnetar. The protons are confined in this region by a strong and localized magnetic field, with lines that are probably shaped like a series of adjacent arcs, resembling the appearance of loops on the surface of the Sun.

Illustration credit: ESA/ATG medialab

Note: For more information, see Weakling Magnetar Reveals Hidden Strength; also, Magnetic Loop on Magnetar SGR 0418.

The Hubble Sequence Throughout the Universe's History

This image shows "slices" of the Universe at different times throughout its history (present day, and at 4 and 11 billion years ago). Each slice goes further back in time, showing how galaxies of each type appear. The shape is that of the Hubble tuning fork diagram, which describes and separates galaxies according to their morphology into spiral (S), elliptical (E), and lenticular (S0) galaxies. On the left of this diagram are the ellipticals, with lenticulars in the middle, and the spirals branching out on the right side. The spirals on the bottom branch have bars cutting through their centers.

The present-day Universe shows big, fully formed and intricate galaxy shapes. As we go further back in time, they become smaller and less mature, as these galaxies are still in the process of forming.

This image is illustrative. the Hubble images of nearby and distant galaxies used were selected based on their appearance; their individual distances are only approximate.

Illustration credit: NASA, ESA, M. Kornmesser

Note: For more information, see Hubble Explores the Origins of Modern Galaxies - Astronomers See True Shapes of Galaxies 11 Billion Years Back in Time.

NGC 1232

NGC 1232: A collision between galaxies about 60 million light years from Earth.

A massive multimillion-degree cloud of gas has been revealed in X-ray data from Chandra (purple) that have been combined with optical data from the Very Large Telescope (blue and white) in this new composite image. The hot gas cloud is likely caused by a collision between a dwarf galaxy and a much larger galaxy called NGC 1232. If confirmed, this discovery would mark the first time such a collision has been detected only in X-rays, and could have implications for understanding how galaxies grow through similar collisions.

Scale: Image is 6.8 arcmin across (About 120,000 light years).

Image credit: X-ray: NASA/CXC/Huntingdon Inst. for X-ray Astronomy/G.Garmire, Optical: ESO/VLT

Note: For more information, see NGC 1232: Dwarf Galaxy Caught Ramming Into a Large Spiral

The Sun's Magnetic Field is About to Flip

Something big is about to happen on the sun. According to measurements from NASA-supported observatories, the sun's vast magnetic field is about to flip.

"It looks like we're no more than 3 to 4 months away from a complete field reversal," says solar physicist Todd Hoeksema of Stanford University. "This change will have ripple effects throughout the solar system."

The sun's magnetic field changes polarity approximately every 11 years. It happens at the peak of each solar cycle as the sun's inner magnetic dynamo re-organizes itself. The coming reversal will mark the midpoint of Solar Cycle 24. Half of 'Solar Max' will be behind us, with half yet to come.

Hoeksema is the director of Stanford's Wilcox Solar Observatory, one of the few observatories in the world that monitor the sun's polar magnetic fields. The poles are a herald of change. Just as Earth scientists watch our planet's polar regions for signs of climate change, solar physicists do the same thing for the sun. Magnetograms at Wilcox have been tracking the sun's polar magnetism since 1976, and they have recorded three grand reversals—with a fourth in the offing.

Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun's polar magnetic fields weaken, go to zero, and then emerge again with the opposite polarity. This is a regular part of the solar cycle."

A reversal of the sun's magnetic field is, literally, a big event. The domain of the sun's magnetic influence (also known as the "heliosphere") extends billions of kilometers beyond Pluto. Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.

When solar physicists talk about solar field reversals, their conversation often centers on the "current sheet." The current sheet is a sprawling surface jutting outward from the sun's equator where the sun's slowly-rotating magnetic field induces an electrical current. The current itself is small, only one ten-billionth of an amp per square meter (0.0000000001 amps/m2), but there’s a lot of it: the amperage flows through a region 10,000 km thick and billions of kilometers wide. Electrically speaking, the entire heliosphere is organized around this enormous sheet.

During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a baseball. As Earth orbits the sun, we dip in and out of the current sheet. Transitions from one side to another can stir up stormy space weather around our planet.

Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy. Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth. The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a better shield against these energetic particles from deep space.

As the field reversal approaches, data from Wilcox show that the sun's two hemispheres are out of synch.

"The sun's north pole has already changed sign, while the south pole is racing to catch up," says Scherrer. "Soon, however, both poles will be reversed, and the second half of Solar Max will be underway."

When that happens, Hoeksema and Scherrer will share the news with their colleagues and the public.

Video credit: NASA

Tracing the Origin of the Magellanic Stream

These images show wide and close-up views of a long ribbon of gas called the Magellanic Stream, which stretches nearly halfway around the Milky Way.

In the combined radio and visible-light image at the top, the gaseous stream is shown in pink. The radio observations from the Leiden/Argentine/Bonn (LAB) Survey have been combined with the Mellinger All-Sky Panorama in visible light. The Milky Way is the light blue band in the center of the image. The brown clumps are interstellar dust clouds in our galaxy. The Magellanic Clouds, satellite galaxies of the Milky Way, are the white regions at the bottom right.

The image at the bottom, taken at radio wavelengths, is a close-up map of the Magellanic Stream that also was generated from the LAB Survey. Researchers determined the chemistry of the gas filament by using Hubble's Cosmic Origins Spectrograph (COS) to measure the amount of heavy elements, such as oxygen and sulfur, at six locations (marked with an "x") along the Magellanic Stream. COS observed light from faraway quasars that passed through the stream, and detected the spectral fingerprints of these elements from the way they absorb ultraviolet light. Quasars are the brilliant cores of active galaxies.

These observations show that most of the gas was stripped from the Small Magellanic Cloud about two billion years ago – but surprisingly, a second region of the stream was formed more recently from the Large Magellanic Cloud. The pink circles to the right mark the location of the Small and Large Magellanic Clouds.

Image credits: Credit for the radio/visible light image: David L. Nidever, et al., NRAO/AUI/NSF and Mellinger, LAB Survey, Parkes Observatory, Westerbork Observatory, and Arecibo Observatory. Credit for the radio image: LAB Survey.

Note: For more information, see Hubble finds source of Magellanic Stream - Astronomers Explore Origin of Gas Ribbon Wrapped Around Our Galaxy.

NGC 2014 and NGC 2020

ESO's Very Large Telescope has captured a detailed view of a star-forming region in the Large Magellanic Cloud — one of the Milky Way's satellite galaxies. This sharp image reveals two glowing clouds of gas. NGC 2014 (right) is irregularly shaped and red and its neighbor, NGC 2020, is round and blue. These odd and very different forms were both sculpted by powerful stellar winds from extremely hot newborn stars that also radiate into the gas, causing it to glow brightly.

Photo credit: ESO

Note: For more information, see The Odd Couple.

Kilonova GRB 130603B

This sequence illustrates the kilonova model for the formation of a short-duration gamma-ray burst. 1. A pair of neutron stars in a binary system spiral together. 2. In the final milliseconds, as the two objects merge, they kick out highly radioactive material. This material heats up and expands, emitting a burst of light called a kilonova. 3. The fading fireball blocks visible light but radiates in infrared light. 4. A remnant disk of debris surrounds the merged object, which may have collapsed to form a black hole.

NASA's Hubble Space Telescope has detected a new kind of stellar blast called a kilonova, which happens when a pair of compact objects such as neutron stars crash together. Hubble observed the fading fireball from a kilonova last month, following a short gamma ray burst (GRB) in a galaxy almost 4 billion light-years from Earth.

"This observation finally solves the mystery of short gamma ray bursts," says Nial Tanvir of the University of Leicester in the United Kingdom, who led a team of researchers conducting this research.

Gamma ray bursts are flashes of intense high-energy radiation that appear from random directions in space. They come in two flavors--long and short. "Many astronomers, including our group, have already provided a great deal of evidence that long-duration gamma ray bursts (those lasting more than two seconds) are produced by the collapse of extremely massive stars," explains Tanvir.

The short bursts, however, were more mysterious.

"We only had weak circumstantial evidence that short bursts [might be] produced by the merger of compact objects," he adds. "This result now appears to provide definitive proof."

Astrophysicists have predicted short-duration GRBs are created when a pair of super-dense neutron stars in a binary system spiral together. This event happens as the system emits gravitational radiation, creating tiny waves in the fabric of space-time. The energy dissipated by the waves causes the two stars to sweep closer together. In the final milliseconds before the explosion, the two stars merge into a death spiral that kicks out highly radioactive material. This material heats up and expands, emitting a burst of light.

The resulting "kilonova" is about 1,000 times brighter than a regular nova, which is caused by the eruption of a white dwarf.

In a recent science paper Jennifer Barnes and Daniel Kasen of the University of California at Berkeley and the Lawrence Berkeley National Laboratory presented new calculations predicting how kilonovas should look. They predicted the same hot plasma producing the radiation also will block the visible light, causing the gusher of energy from the kilonova to flood out in near-infrared light over several days.

An unexpected opportunity to test this model came June 3 when NASA' s Swift space telescope picked up the extremely bright gamma ray burst, cataloged as GRB 130603B. Although the initial blast of gamma rays lasted just one-tenth of a second, it was roughly 100 billion times brighter than the subsequent kilonova flash.

From June 12-13, Hubble searched the location of the initial burst, spotting a faint red object. An independent analysis of the data from another research team confirmed the detection. Subsequent Hubble observations on July 3 revealed the source had faded away, therefore providing the key evidence the infrared glow was from an explosion accompanying the merger of two objects.

The team's results appeared August 3 in a special online publication of the journal Nature.

Text credit: NASA; Image credit (top): NASA, ESA, and A. Feild (STScI); (bottom): NASA, ESA, N. Tanvir (University of Leicester), A. Fruchter (STScI), and A. Levan (University of Warwick)

Protostar RNO 91 in Nebula LDN 43

A very young star, RNO 91, is being born in the guts of the dark cloud LDN 43, 520 light-years from Earth in the constellation of Ophiuchus. The newborn star is hidden in this image, revealed only by light reflected onto the plumes of the dark cloud. A dusty, icy disc surrounding it may host planet embryos.

Photo credit: ESA/Hubble & NASA; Acknowledgement: J. Schmidt

Orbits of Potentially Hazardous Asteroids (PHAs)

This graphic shows the orbits of all the known Potentially Hazardous Asteroids (PHAs), numbering over 1,400 as of early 2013. These are the asteroids considered hazardous because they are fairly large (at least 460 feet or 140 meters in size), and because they follow orbits that pass close to the Earth's orbit (within 4.7 million miles or 7.5 million kilometers). But being classified as a PHA does not mean that an asteroid will impact the Earth: None of these PHAs is a worrisome threat over the next hundred years. By continuing to observe and track these asteroids, their orbits can be refined and more precise predictions made of their future close approaches and impact probabilities.

Image credit: NASA/JPL-Caltech

Abell 2199 and ISCS 1433.9+3330

This image shows two of the galaxy clusters observed by NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope missions. Galaxy clusters are among the most massive structures in the universe. The central and largest galaxy in each grouping, called the brightest cluster galaxy or BCG, is seen at the center of each image.

Figure 1 shows the cluster known as Abell 2199, which is relatively nearby at a distance of 400 million light-years from Earth (redshift of 0.0302). This image combines infrared data from WISE (in red) with shorter wavelengths of light extending into the visible spectrum from the Sloan Digital Sky Survey (in blue and green).

Figure 2 is the cluster ISCS 1433.9+3330, which is significantly farther away at a distance of 4.4 billion light-years (redshift of 0.42). Infrared data from Spitzer (red) is combined with similar shorter wavelength data taken by the Mayall Telescope on Kitt Peak, Arizona.

Photo credit: NASA/JPL-Caltech/SDSS/NOAO

Note: For more information, see Monster Galaxies Lose Their Appetite With Age.

Tagus Valles

In the ancient cratered southern highlands of Mars, the faint traces of a wet past are seen in the form of channels (lower center), fluidized debris around craters (bottom right) and blocks of eroded sediments (top left). Volcanic activity may have deposited the fine dusting of dark material visible in the top left.

The image was taken by the High Resolution Stereo Camera on ESA’s Mars Express on 15 January 2013 (orbit 11504), with a ground resolution of approximately 22 m per pixel. The image center lies at about 4°S / 114°E, close to Tagus Valles in an unnamed region north of Hesperia Planum.

Photo credit: ESA/DLR/FU Berlin (G. Neukum)

Note: For more information, see Tagus Valles Topography and Tagus Valles 3D.

Quenched Galaxies in the COSMOS Survey

This image shows 20 of the quenched galaxies - galaxies that are no longer forming stars - seen in the Hubble COSMOS observations. Each galaxy is identified by a crosshair at the center of each frame.

Quenched galaxies in the distant Universe are much smaller than those seen nearby. It was thought that these small galaxies merged with other smaller, gas-free galaxies to grow bigger, but it turns out that larger galaxies were "switching off" at later times and adding their numbers to those of their smaller and older siblings, giving the mistaken impression of individual galaxy growth over time.

Image credit: NASA, ESA, M. Carollo (ETH Zurich)

Note: For more information, see When Galaxies Switch Off - Hubble's COSMOS Survey Solves 'Quenched' Galaxy Mystery.

"Blinking" Binary Star System YLW 16A

In this artist's impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to "blink" every 93 days.

The dusty hula hoop itself is misaligned from the central star pair, thanks to the disrupting gravitational presence of a third star orbiting at the periphery of the system. The light yellow arcs near the two central stars indicate their movement relative to each other and the disk. It is believed that this disk will go on to spawn planets and the other celestial bodies that make up a solar system.

NASA's Spitzer Space Telescope observed this system, called YLW 16A, in the infrared light emitted by the disk's warmed gas and dust.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Spitzer Discovers Young Stars with a 'Hula Hoop.'