Kepler Observes Neptune and Its Moons Triton and Nereid

Seventy days worth of nearby planetary group perceptions from NASA’s Kepler shuttle, taken amid its rethought “K2″ mission, are highlighted in this accelerated film. The planet Neptune shows up on day 15, trailed by its moon Triton, which looks little and weak. Sharp peered toward onlookers can likewise detect Neptune’s minor moon Nereid at day 24. Neptune is not going in reverse but rather seems to do as such due to the changing position of the Kepler rocket as it circles around the sun. Credits: NASA Ames/SETI Institute/J. Rowe

This short feature demonstrates 70 days of Kepler perceptions of Neptune and its moons Triton and Nereid compacted into 34 second.

NASA’s Kepler rocket, known for its planet-chasing ability of different stars, is likewise concentrating on nearby planetary group objects. In its new K2 mission, Neptune and two of its moons, Triton and Nereid, have been imaged. The motion picture delineates 70 days of continuous perception making this one of the more drawn out constant investigations of an external nearby planetary group object.

The film, in view of 101,580 pictures taken from November 2014 through January 2015 amid K2’s Campaign 3, uncovers the never-ending perfect timing of our close planetary system. The 70-day timespan is compacted into 34 seconds with the quantity of days noted in the upper right corner.

Neptune shows up on day 15 however does not travel alone in the feature. The little swoon question nearly circling is its huge moon Triton, which circles Neptune like clockwork. Showing up from the left at day 24, sharp looked at onlookers can likewise detect the small moon Nereid in its moderate 360-day circle around the planet. A couple quick moving space rocks show up in the film, appearing as streaks over the K2 field of perspective. The red spots are a couple of the stars K2 analyzes in its look for traveling planets outside of our close planetary system.

Neptune’s air reflects daylight making a brilliant appearance. The reflected light surges various pixels of the space apparatus’ ready cam, delivering the brilliant spikes reaching out above and beneath the planet. The heavenly bodies in the sewed together pictures are shaded red to speak to the wavelength reaction of the space apparatus’ cam. As a general rule, Neptune is dark blue in shading and its moons and the speeding space rocks are light dim while the foundation stars seem white from a separation.

Relative circle paces clarify the fascinating movement of Neptune and its moons starting at day 42. Internal planets like Earth circle more rapidly than external planets like Neptune. In the film, Neptune’s clear movement in respect to the stationary stars is generally because of the round 372-day circle of the Kepler rocket around the sun. In the event that you take a gander at far off items and move your head forward and backward, you will see that questions near to you will likewise seem to move forward and backward, in respect to protests far away. The same idea is delivering the clear movement of Neptune.

While NASA’s Kepler shuttle is known for its revelations of planets around different stars, a global group of stargazers arrangements to utilize these information to track Neptune’s climate and test the planet’s inward structure by contemplating unpretentious shine variances that must be seen with K2.

NASA’s Ames Research Center in Moffett Field, California, deals with the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA’s Jet Propulsion Laboratory in Pasadena, California, oversaw Kepler mission improvement. Ball Aerospace & Technologies Corp. works the flight framework with backing from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Hubble Reveals Diffusion of Stars Through the Core of the Globular Cluster 47 Tucanae

The heart of the goliath globular star bunch 47 Tucanae in the Hubble Space Telescope picture at left uncovers the shine of 200,000 stars. The green box diagrams the bunch’s swarmed center, where Hubble saw a parade of youthful white midgets beginning their moderate paced 40-million-year adventure to the less populated rural areas. The stellar relics are excessively black out, making it impossible to be seen plainly in noticeable light, as indicated in the Hubble picture at upper right. However, in bright light the stars gleam splendidly on the grounds that they are greatly hot, as indicated in the picture at base right, taken by Hubble’s Wide Field Camera 3. The green circles in the picture plot the brightest of the youthful white diminutive people spied by Hubble.

New pictures from the Hubble Space Telescope show interestingly depictions of white small stars starting their 40-million-year movement from the swarmed focus of an old star bunch to the less populated rural areas.

White diminutive people are the wore out relics of stars that quickly lose mass, chill down and close their atomic heaters. As these gleaming corpses age and shed weight, their circles start to grow outward from the star bunch’s pressed downtown. This relocation is brought about by a gravitational tussle among stars inside the group. Globular star groups deal with stars as per their mass, administered by a gravitational billiard ball game where lower mass stars loot force from more monstrous stars. The outcome is that heavier stars back off and sink to the group’s center, while lighter stars get speed and move over the bunch to the edge. This procedure is known as “mass isolation.” Until these Hubble perceptions, cosmologists had never absolutely seen the dynamical transport line in real life.

Cosmologists utilized Hubble to watch the white-diminutive person departure in the globular star group 47 Tucanae, a thick swarm of countless stars in our Milky Way system. The group lives 16,700 light-years away in the southern heavenly body Tucana.

“We’ve seen the last picture before: white smaller people that have officially gotten themselves straightened out and are circling in an area outside the center that is fitting for their mass,” clarified Jeremy Heyl of the University of British Columbia (UBC), Vancouver, Canada, first creator on the science paper. The group’s outcomes showed up in the May 1 issue of The Astrophysical Journal.

“Anyway, in this study, which involves around a quarter of all the white smaller people in the group, we’re really getting the stars during the time spent moving outward and isolating themselves as indicated by mass,” Heyl said. “The whole process doesn’t take long, just a couple of countless years, out of the 10-billion-year age of the bunch, for the white midgets to achieve their new home in the external rural areas.”

“This outcome hasn’t been seen some time recently, and it provokes a few thoughts regarding a portion of the points of interest of how and when a star loses its mass close to the end of its life,” Added colleague Harvey Richer of UBC.

Utilizing the bright light abilities of Hubble’s sharp-looked at Wide Field Camera 3, the space experts inspected 3,000 white diminutive people, following two populaces with various ages and circles. One gathering was 6 million years of age and had quite recently started their excursion. Another was around 100 million years of age and had officially landed at its new property far from the inside, approximately 1.5 light-years, or almost 9 trillion miles, away.

No one but Hubble can distinguish these stars in light of the fact that bright light is obstructed by Earth’s air and subsequently doesn’t achieve ground-based telescopes. The space experts assessed the white midgets’ ages by examining their hues, which issues them the stars’ temperatures. The most sultry midgets sparkle wildly in bright light.

The midgets were hurled out of the unpleasant and-tumble group focus because of gravitational communications with heftier stars circling the locale. Stars in globular bunches get themselves straightened out by weight, with the heavier stars sinking to the center. Before blazing out as white diminutive people, the relocating stars were among the most huge in the bunch, measuring generally as much as our sun; the more gigantic stars wore out long back.

The moving white midgets, nonetheless, are not in a rush to leave. Their circles extend outward at around 30 miles 60 minutes, generally the normal rate of an auto going in the city. The dead stars will proceed with this pace for around 40 million years, until they achieve an area that is more fitting for their mass.

In spite of the fact that the stargazers were not astonished to see the relocation, they were confused to find that the most youthful white diminutive people were simply leaving on their voyage. This disclosure may be confirmation that the stars shed a lot of their mass at a later stage in their lives than once suspected.

Around 100 million years prior to stars advance into white diminutive people, they swell up and get to be red goliath stars. Numerous space experts imagined that stars lose a large portion of their mass amid this stage by brushing it off into space. Be that as it may, the Hubble perceptions uncover that the stars really dump 40 percent to 50 percent of their mass only 10 million years prior totally wearing out as white smaller people.

“This poor start is proof that these white midgets are losing a lot of mass just before they get to be white diminutive people and not amid the prior red titan stage, as most space experts had thought,” said Richer. “That is the reason we are seeing stars still during the time spent moving gradually far from the focal point of the bunch. It’s when they lose their mass that they get gravitationally pushed out of the center. On the off chance that the stars had shed the vast majority of their weight prior in their lives, we wouldn’t see such an emotional impact between the most youthful white diminutive people and the more seasoned ones that are 100 million years of age.”

Despite the fact that the white diminutive people have depleted the hydrogen fuel that makes them sparkle as stars, these stellar relics are among the brightest stars in this primordial bunch in light of the fact that their splendid hot centers have been uncovered, which are brilliant to a great extent in bright light.

“At the point when a white smaller person structures, they’ve got this put away up warmth in their centers, and the reason we can see a white midget is on account of after some time they transmit their put away warm vitality gradually into space,” Richer clarified. “They’re getting cooler and less iridescent over the long haul in light of the fact that they have no atomic wellsprings of vitality.”

Subsequent to enduring the gauntlet of gravitational cooperations inside of the swarmed 1.5-light extensive center, the voyaging white smaller people experience couple of connections as they move outward, on the grounds that the thickness of stars reductions. “A considerable measure of activity happens when they’re 30 million to 40 million years of age, and proceeds up to around 100, and afterward as they get more seasoned the white midgets still develop however less drastically,” Heyl said.

The 47 Tucanae group is a perfect spot to study the mass isolation of white diminutive people in light of the fact that it is close-by and has a critical number of halfway thought stars that can be determined by Hubble’s fresh vision.

The Hubble Space Telescope is an undertaking of global participation in the middle of NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, deals with the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is worked for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

Strangulation is the Basic Mechanism for Star Formation Shut Down

Craftsman’s impression of one of the conceivable galaxy strangulation systems: star-shaping universes (sustained by gas inflows) are accumulated into an enormous hot corona, which “strangles” them and prompts their passing.

Utilizing information from the Sloan Digital Sky Survey, space experts from the University of Cambridge subtle element why certain universes can longer deliver stars.

As homicide secrets go, its a major one: how do cosmic systems pass on and what slaughters them? Another study,published today in the diary Nature, has found that the essential driver of galactic passing is strangulation, which happens after cosmic systems are cut off from the crude materials expected to make new stars.

Scientists from the University of Cambridge and the Royal Observatory Edinburgh have found that levels of metals contained in dead cosmic systems give key ‘fingerprints’, making it conceivable to focus the reason for death.

There are two sorts of universes in the Universe: generally half are “alive” cosmic systems which create stars, and the other half are “dead” ones which don’t. Alive universes, for example, our own particular Milky Way are rich vulnerable gas – generally hydrogen – expected to deliver new stars, while dead systems have low supplies. What had been obscure is what’s in charge of murdering the dead ones.

Cosmologists have think of two fundamental theories for galactic demise: either the icy gas expected to create new stars is all of a sudden “drained” out of the systems by interior or outer strengths, or the supply of approaching chilly gas is some way or another halted, gradually strangling the galaxy to death more than a delayed time of time.

Keeping in mind the end goal to get to the base of this secret, the group utilized information from the Sloan Digital Sky Survey to dissect metal levels in more than 26,000 normal measured cosmic systems situated in our side of the universe.

“Metals are an intense tracer of the historical backdrop of star development: the more stars that are framed by a galaxy, the more metal substance you’ll see,” said Dr Yingjie Peng of Cambridge’s Cavendish Laboratory and Kavli Institute of Cosmology, and the paper’s lead creator. “So taking a gander at levels of metals in dead systems ought to have the capacity to let us know how they kicked the bucket.”

On the off chance that cosmic systems are slaughtered by surges abruptly hauling the icy gas out of the universes, then the metal substance of a dead galaxy ought to be the same as just before it passed on, as star arrangement would unexpectedly stop.

On account of death by strangulation nonetheless, the metal substance of the galaxy would continue rising and in the end stop, as star development could proceed until the current chilly gas gets totally spent.

While it is unrealistic to dissect singular universes because of the huge timescales included, by measurably exploring the distinction of metal substance of alive and dead cosmic systems, the scientists had the capacity focus the reason for death for most worlds of normal size.

“We found that for a given stellar mass, the metal substance of a dead galaxy is fundamentally higher than a star-framing galaxy of comparable mass,” said Professor Roberto Maiolino, co-creator of the new study. “This isn’t what we’d hope to see on account of sudden gas evacuation, yet it is reliable with the strangulation situation.”

The scientists were then ready to freely test their outcomes by taking a gander at the stellar age contrast between star-shaping and dead worlds, free of metal levels, and discovered a normal age distinction of four billion years – this is in concurrence with the time it would take for a star-framing galaxy to be strangled to death, as surmised from the metallicity investigation.

“This is the first definitive proof that systems are being strangled to death,” said Peng. “What’s next however, is making sense of what’s bringing on it. Basically, we know the reason for death, however we don’t yet know who the killer is, albeit there are a couple suspects”

The Changing Frequency of Galaxy Collisions

New research from the Illustris project examines the changing frequency of galaxy collisions, as the universe evolves from the big bang to the present day. Our knowledge of the big bang has increased dramatically in the past decade, as satellites and ground-based studies of the cosmic microwave background have refined parameters associated with the very early universe, achieving amazing precisions (though not necessarily accuracies) of a few percent. Unfortunately, our knowledge of what happened after that – from those first few hundred thousand years until today, 13.7 billion years later – is very much a work-in-progress. We know that galaxies and their stars formed out of the cooling, filamentary network of matter from that early era. They re-ionized the hydrogen gas, and then continued to evolve, and collide with one another as the universe steadily expanded. Distant galaxies are faint and hard to detect, however, and although observations have made excellent progress in piecing together the story line, astronomers have turned to theory and computer simulations to try to complete the picture. There are three main theoretical approaches to study the cosmic frequency of galaxy mergers, which differ in how they model galaxies. The first approach does not attempt to model galaxy formation from first principles, and instead “paints” galaxies onto the dark matter environment (they are called “halos”) according to constraints set by observations. The second approach models galaxy formation by means of simple mathematical recipes, again using dark matter halos as the backbone of the model. The third method, hydrodynamic simulations, attempts to model everything (dark matter, gas and stars) self-consistently, a task that until recently had been computationally too difficult. https://youtu.be/NjSFR40SY58 The Illustris simulation is the most ambitious computer simulation of our Universe yet performed. The calculation tracks the expansion of the universe, the gravitational pull of matter onto itself, the motion of cosmic gas, as well as the formation of stars and black holes. These physical components and processes are all modeled starting from initial conditions resembling the very young universe 300,000 years after the Big Bang and until the present day, spanning over 13.8 billion years of cosmic evolution. The simulated volume contains tens of thousands of galaxies captured in high-detail, covering a wide range of masses, rates of star formation, shapes, sizes, and with properties that agree well with the galaxy population observed in the real universe. The simulations were run on supercomputers in France, Germany, and the US. The largest was run on 8,192 compute cores, and took 19 million CPU hours. A single state-of-the-art desktop computer would require more than 2000 years to perform this calculation.Find out more at: http://www.illustris-project.org CfA astronomers Vicente Rodriguez-Gomez, Shy Genel, Annalisa Pillepich, Dylan Nelson, and Lars Hernquist and their colleagues have developed a new theoretical framework for calculating the frequency of galaxy mergers in the Illustris Project, a cosmological hydrodynamic simulation which models the formation of galaxies in cosmic volumes about three hundred million light-years in size, huge enough to replicate many known properties of galaxies and clusters both locally and at earlier epochs. The large volume, the self-consistent treatment of normal matter, and the realistic galaxy formation model used, allows the Illustris simulation to provide an unprecedented and precise study of mergers over cosmic time. The astronomers find clear evidence for steadily decreasing galaxy merger rates (the merger frequency three billion years after the big bang was about fifteen times higher than it is today), and they clarify the nature of mergers, for example, finding the most useful definition for the mass ratio of the merging galaxies and constraining the epoch of mass infall during a collision. They report some sharp differences between their results and those predicted by some other popular theories, as well as some ambiguities in the (still imprecise) observed datasets. Their important research marks the start of a more detailed series of investigations into the cosmic evolution of galaxies. Publication: Vicente Rodriguez-Gomez, et al., “The Merger Rate of Galaxies in the Illustris Simulation: A Comparison with Observations and Semi-empirical Models,” MNRAS (May 1, 2015) 449 (1): 49-64; doi: 10.1093/mnras/stv264 Source: Harvard-Smithsonian Center for Astrophysics Image: The Illustris Project

Serene Saturn – Cassini Image of Saturn and Mimas

Taken by NASA’s Cassini Spacecraft, this image shows Saturn and Mimas using a spectral filter centered at 752 nanometers, in the near-infrared portion of the spectrum.

From a distance Saturn seems to exude an aura of serenity and peace.

In spite of this appearance, Saturn is an active and dynamic world. Its atmosphere is a fast-moving and turbulent place with wind speeds in excess of 1,100 miles per hour (1,800 km per hour) in places. The lack of a solid surface to create drag means that there are fewer features to slow down the wind than on a planet like Earth.

Mimas, to the upper-right of Saturn, has been brightened by a factor of 2 for visibility.

In this view, Cassini was at a subspacecraft latitude of 19 degrees North. The image was taken with the Cassini spacecraft wide-angle camera on February 4, 2015 using a spectral filter centered at 752 nanometers, in the near-infrared portion of the spectrum.

The view was obtained at a distance of approximately 1.6 million miles (2.5 million kilometers) from Saturn. Image scale is 96 miles (150 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Source: NASA

Image: NASA/JPL-Caltech/Space Science Institute

New Images by NASA’s Dawn Spacecraft Show Mysterious Bright Spots on Ceres

A new sequence of images taken by NASA’s Dawn spacecraft shows the mysterious bright spots on the dwarf planet Ceres. The images were taken on May 3 and 4, 2015 from a distance of 8,400 miles (13,600 kilometers).

In this closest-yet view, the brightest spots within a crater in the northern hemisphere are revealed to be composed of many smaller spots. However, their exact nature remains unknown.

“Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice,” said Christopher Russell, principal investigator for the Dawn mission from the University of California, Los Angeles.

These images offer scientists new insights into crater shapes and sizes, and a host of other intriguing geological features on the surface. The image resolution is 0.8 mile (1.3 kilometers) per pixel.

Dawn has now concluded its first mapping orbit, in which it completed one 15-day full circle around Ceres while making a host of new observations with its scientific instruments. On May 9, the spacecraft powered on its ion engine to begin the month-long descent toward its second mapping orbit, which it will enter on June 6. In this next phase, Dawn will circle Ceres about every three days at an altitude of 2,700 miles (4,400 kilometers) — three times closer than the previous orbit. During this phase, referred to as Dawn’s survey orbit, the spacecraft will comprehensively map the surface to begin unraveling Ceres’ geologic history and assess whether the dwarf planet is active. The spacecraft will pause twice to take images of Ceres as it spirals down into this new orbit.

Dawn is the first mission to visit a dwarf planet, and the first to orbit two distinct solar system targets. It studied giant asteroid Vesta for 14 months in 2011 and 2012, and arrived at Ceres on March 6, 2015.

Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

Source: Elizabeth Landau, NASA’s Jet Propulsion Laboratory

Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Hubble Views Elliptical Galaxy NGC 3923

This Hubble image of the week shows elliptical galaxy NGC 3923, which is located over 90 million light-years away in the constellation of Hydra.

NGC 3923 is an example of a shell galaxy where the stars in its halo are arranged in layers.

Finding concentric shells of stars enclosing a galaxy is quite common and is observed in many elliptical galaxies. In fact, every tenth elliptical galaxy exhibits this onion-like structure, which has never been observed in spiral galaxies. The shell-like structures are thought to develop as a consequence of galactic cannibalism, when a larger galaxy ingests a smaller companion. As the two centers approach, they initially oscillate about a common center, and this oscillation ripples outwards forming the shells of stars just as ripples on a pond spread when the surface is disturbed.

NGC 3923 has over twenty shells, with only a few of the outer ones visible in this image and its shells are much more subtle than those of other shell galaxies. The shells of this galaxy are also interestingly symmetrical, while other shell galaxies are more skewed.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.

Source: Hubble Space Telescope

Image: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt

Halo Around the Andromeda Galaxy is Larger Than Previously Thought

Using the Hubble Space Telescope, astronomers have discovered that the immense halo of gas enveloping the Andromeda galaxy is about six times larger and 1,000 times more massive than previously thought.

The dark, nearly invisible halo stretches about a million light-years from its host galaxy, halfway to our own Milky Way galaxy. This finding promises to tell astronomers more about the evolution and structure of majestic giant spirals, one of the most common types of galaxies in the universe.

“Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies according to models of galaxy formation,” explained the lead investigator Nicolas Lehner of the University of Notre Dame, Indiana. The gargantuan halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of a hot, diffuse gas. If it could be viewed with the naked eye, the halo would be 100 times the diameter of the full moon in the sky. This is equivalent to the patch of sky covered by two basketballs held at arm’s length.

The Andromeda galaxy lies 2.5 million light-years away and looks like a faint spindle, about 6 times the diameter of the full moon. It is considered a near-twin to the Milky Way galaxy.

Because the gas in Andromeda’s halo is dark, the team looked at bright background objects through the gas and observed how the light changed. This is a bit like looking at a glowing light at the bottom of a pool at night. The ideal background “lights” for such a study are quasars, which are very distant bright cores of active galaxies powered by black holes. The team used 18 quasars residing far behind Andromeda to probe how material is distributed well beyond the visible disk of the galaxy. Their findings were published in the May 4, 2015 edition of the Astrophysical Journal.

Earlier research from Hubble Cosmic Origins Spectrograph (COS)-Halos program studied 44 distant galaxies and found halos like Andromeda’s, but never before has such a massive halo been seen in a neighboring galaxy. Because the previously studied galaxies were much farther away, they appeared much smaller on the sky. Only one quasar could be detected behind each faraway galaxy, providing only one light anchor point to map their halo size and structure. With its close proximity to Earth and its correspondingly large footprint on the sky, Andromeda provides a far more extensive sampling of a lot of background quasars.

“As the light from the quasars travels toward Hubble, the halo’s gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range,” explains co-investigator J. Christopher Howk, also of Notre Dame. “By measuring the dip in brightness in that range, we can tell how much gas there is between us and that quasar.”

The scientists used Hubble’s unique capability to study the ultraviolet light from the quasars. Ultraviolet light is absorbed by Earth’s atmosphere, which makes it difficult to observe with a ground-based telescope. The team drew from about 5 years worth of observations stored in the Hubble data archive to conduct this research. Many previous Hubble campaigns have used quasars to study gas much farther away than — but in the general direction of — Andromeda, so a treasure trove of data already existed.

But where did the giant halo come from? Large-scale simulations of galaxies suggest that the halo formed at the same time as the rest of Andromeda. The team also determined that it is enriched in elements much heavier than hydrogen and helium, and the only way to get these heavy elements is from exploding stars called supernovae. The supernovae erupt in Andromeda’s star-filled disk and violently blow these heavier elements far out into space. Over Andromeda’s lifetime, nearly half of all the heavy elements made by its stars have been expelled far beyond the galaxy’s 200,000 light-year diameter stellar disk.

What does this mean for our own galaxy? Because we live inside the Milky Way, scientists cannot determine whether or not such an equally massive and extended halo exists around our galaxy. It’s a case of not being able to see the forest for the trees. If the Milky Way does possess a similarly huge halo, the two galaxies’ halos may be nearly touching already and quiescently merging long before the two massive galaxies collide. Hubble observations indicate that the Andromeda and Milky Way galaxies will merge to form a giant elliptical galaxy beginning about 4 billion years from now.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

Publication: Nicolas Lehner, et al., “Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy,” 2015, ApJ, 804, 79; doi:10.1088/0004-637X/804/2/79

Source: Rob Gutro, NASA’s Goddard Space Flight Center

Image: NASA/STScI

NASA’s NuSTAR Finds Evidence of a Lopsided Star Explosion

By mapping the radioisotope titanium-44, NASA’s NuStar reveals evidence of an asymmetrical explosion from supernova 1987A and helps to explain the mechanics of SN 1987A and of core-collapse supernovae in general.

NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has found evidence that a massive star exploded in a lopsided fashion, sending ejected material flying in one direction and the core of the star in the other.

The findings offer the best proof yet that star explosions of this type, called Type II or core-collapse supernovae, are inherently asymmetrical, a phenomenon that had been difficult to prove before now.

“Stars are spherical objects, but apparently the process by which they die causes their cores to be turbulent, boiling and sloshing around in the seconds before their demise,” said Steve Boggs of the University of California, Berkeley, lead author of a new study on the findings, appearing in the May 8 issue of Science. “We are learning that this sloshing leads to asymmetrical explosions.”

The supernova remnant in the study, called 1987A, is 166,000 light-years away. Light from the blast that created the remnant lit up skies above Earth in 1987. While other telescopes had found hints that this explosion was not spherical, NuSTAR found the “smoking gun” in the form of a radioisotope called titanium-44.

“Titanium is produced in the very heart of the explosion, so it traces the shape of the engine driving the disassembly of the star,” said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology in Pasadena. “By looking at the shift of the energy of the X-rays coming from titanium, the NuSTAR data revealed that, surprisingly, most of the material is moving away from us.”

Last year, NuSTAR created detailed titanium-44 maps of another supernova remnant, called Cassiopeia A, also finding evidence of an asymmetrical explosion, though not to as great an extent as in 1987A. Together, these results suggest that lopsidedness is at the very root of core-collapse supernova.

When supernova 1987A first lit up our skies decades ago, telescopes around the world had a unique opportunity to watch the event unfold and evolve. Outer, ejected materials lit up first, followed by the innermost materials powered by radioactive isotopes, such as cobalt-56, which decayed into iron-56. In 2012, the European Space Agency’s Integral satellite detected titanium-44 in 1987A. Titanium-44 continues to blaze in the supernova remnant due to its long lifetime of 85 years.

“In some ways, it is as if 1987A is still exploding in front of our eyes,” said Boggs.

NuSTAR brought a new tool to the study of 1987A. Thanks to the observatory’s sharp high-energy X-ray vision, it has made the most precise measurements of titanium-44 yet. This radioactive material is produced at the core of a supernova, so it provides astronomers with a direct probe into the mechanisms of a detonating star.

The NuSTAR spectral data reveal that titanium-44 is moving away from us with a velocity of 1.6 million mph (2.6 million kilometers per hour). That indicates ejected material flung outward in one direction, while the compact core of the supernova, called a neutron star, seems to have kicked off in the opposite direction.

“These explosions are driven by the formation of a compact object, the remaining core of the star, and this seems to be connected to the core blasting one direction, and the ejected material, the other,” said Boggs.

Previous observations have hinted at the lopsided nature of supernova blasts, but it was impossible to confirm. Telescopes like NASA’s Chandra X-ray Observatory, which sees lower-energy X-rays than NuSTAR, had spotted iron that had been heated in the 1987A blast, but it was not clear if the iron was generated in the explosion or just happened to have been in the vicinity.

“Radioactive titanium-44 glows in the X-rays no matter what and is only produced in the explosion,” said Brian Grefenstette, a co-author of the study at Caltech. “This means that we don’t have to worry about how the environment influenced the observations. We are able to directly observe the material ejected in the explosion.”

Future studies by NuSTAR and other telescopes should further illuminate the warped nature of supernovae. Is 1987A particularly askew, or in line with other objects in its class? A decades-old mystery continues to unravel before our eyes.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington.

Publication: S. E. Boggs, et al., “44Ti gamma-ray emission lines from SN1987A reveal an asymmetric explosion,” Science 8 May 2015: Vol. 348 no. 6235 pp. 670-671; DOI: 10.1126/science.aaa2259

Source: Whitney Clavin, Jet Propulsion Laboratory

Images: ESA/Hubble & NASA; NASA/JPL-Caltech/UC Berkeley

Activity on Enceladus Could Be ‘Curtain Eruptions’

A newly published study reveals that most of the eruptions from Saturn’s moon Enceladus might be diffuse curtains rather than discrete jets.

Many features that appear to be individual jets of material erupting along the length of prominent fractures in Enceladus’ south polar region might be phantoms created by an optical illusion, according to a new study published on Thursday, May 7, in the journal Nature.

“We think most of the observed activity represents curtain eruptions from the ‘tiger stripe’ fractures, rather than intermittent geysers along them,” said Joseph Spitale, lead author of the study and a participating scientist on the Cassini mission at the Planetary Science Institute in Tucson, Arizona. “Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets.”

In analyzing Cassini’s images of the eruptions on Enceladus, Spitale and colleagues took particular note of the faint background glow present in most images. The brightest eruption features, which appear to be discrete jets, look to them to be superimposed intermittently upon this background structure.

Recent research suggests much of the eruption activity on the surface of Saturn’s moon Enceladus could be in the form of broad, curtain-like eruptions, rather than discrete jets.

The researchers modeled eruptions on Enceladus as uniform curtains along the tiger stripe fractures. They found that phantom brightness enhancements appear in places where the viewer is looking through a “fold” in the curtain. The folds exist because the fractures in Enceladus’ surface are more wavy than perfectly straight. The researchers think this optical illusion is responsible for most of what appear to be individual jets.

“The viewing direction plays an important role in where the phantom jets appear,” said Spitale. “If you rotated your perspective around Enceladus’ south pole, such jets would seem to appear and disappear.”

Phantom jets in simulated images produced by the scientists line up nicely with some of the features in real Cassini images that appear to be discrete columns of spray. The correspondence between simulation and spacecraft data suggests that much of the discrete-jet structure is an illusion, according to the researchers.

Curtain eruptions occur on Earth where molten rock, or magma, gushes out of a deep fracture. These eruptions, which often create spectacular curtains of fire, are seen in places such as Hawaii, Iceland and the Galapagos Islands.

“Our understanding of Enceladus continues to evolve, and we’ve come to expect surprises along the way,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, who was not involved in the study. “This little ice world is becoming more exciting, not less, as we tease out new details about its subsurface ocean and astonishing geophysical activity.”

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Publication: Joseph N. Spitale, et al., “Curtain eruptions from Enceladus’ south-polar terrain,” Nature 521, 57–60 (07 May 2015); doi:10.1038/nature14368

Source: Preston Dyches, Jet Propulsion Laboratory

Image: NASA/JPL-Caltech/SSI/PSI