In this image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile young stars huddle together against a backdrop of clouds of glowing gas and lanes of dust. The star cluster, known as NGC 3293, would have been just a cloud of gas and dust itself about ten million years ago, but as stars began to form it became the bright group we see here. Clusters like this are celestial laboratories that allow astronomers to learn more about how stars evolve.
Credit:
ESO/G. Beccari
Any human being knows the awe-inspiring wonder of a splash of stars against a dark backdrop. But it takes a skilled someone to truly appreciate a distant object viewed through an eyepiece. Your gut tightens as you realize that the tiny fuzzy blob is really thousands of light-years away.
That wave of amazement is encouraged by understanding and knowledge.
Stunning photographs of the cosmos further convey the beauty that arises from the simple interplay of dust, light and gas on absolutely massive and distant scales. The striking image above from ESO’s La Silla Observatory in Chile is but one example.
Stars are born in enormous clouds of gas and dust. Small pockets in these clouds collapse under the pull of gravity, eventually becoming so hot that they ignite nuclear fusion. The result is a cluster of tens to hundreds of thousands of stars bound together by their mutual gravitational attraction.
Every star in a cluster is roughly the same age and has the same chemical composition. They’re the closest thing astronomers have to a controlled laboratory environment.
This chart shows the location of the bright open star cluster NGC 3293 (marked by a red circle) in the southern constellation of Carina. Image Credit: ESO / IAU / Sky & Telescope
The star cluster, NGC 3293, is located 8000 light-years from Earth in the constellation of Carina. It was first spotted by the French astronomer Nicolas-Louis de Lacaille during his stay in South Africa in 1751. Because it stands as one of the brightest clusters in the southern sky, de Lacaille was able to site it in a tiny telescope with an aperture of just 12 millimeters.
The cluster is less than 10 million years old, as can be seen by the abundance of hot, blue stars. Despite some evidence suggesting that there is still some ongoing star formation, it is thought that most, if not all, of the nearly 50 stars were born in one single event.
But even though these stars are all the same age, they do not all have the dazzling appearance of stars in their infancy. Some look positively elderly. The reason is simple: stars of different size, evolve at different speeds. More massive stars speed through their evolution, dying quickly, while less massive stars can live tens of billions of years.
Take the bright orange star at the bottom right of the cluster. Stars initially draw their energy from burning hydrogen into helium deep within their cores. But this star ran out of hydrogen fuel faster than its neighbors, and quickly evolved into a cool and bright, giant star with a contracted core but an extended atmosphere.
It’s now a cool, red giant, in a new stage of evolution, while its neighbors remain hot, young stars.
Eventually the star will collapse under its own gravity, throwing off its outer layers in a supernova explosion, and leaving behind a neutron star or a black hole. The peppering shock waves will likely initiate further star formation in the ever-changing laboratory.
A collection of images from the Chandra X-Ray Observatory marking its 15th anniversary in space. Top, from left: the crab Nebula, supernova remnant G292.0+1.8 and the Crab Nebula. At bottom, supernova remnant 3C58. Credit: NASA/CXC/SAO
It’s well past the Fourth of July, but you can still easily find fireworks in the sky if you look around. The Chandra X-Ray Observatory has been doing just that for the past 15 years, revealing what the universe looks like in these longer wavelengths that are invisible to human eyes.
Just in time for the birthday, NASA released four pictures that Chandra took of supernova (star explosion) remnants it has observed over the years. The pictures stand as a symbol of what the telescope has shown us so far.
“Chandra changed the way we do astronomy. It showed that precision observation of the X-rays from cosmic sources is critical to understanding what is going on,” stated Paul Hertz, NASA’s Astrophysics Division director, in a press release. “We’re fortunate we’ve had 15 years – so far – to use Chandra to advance our understanding of stars, galaxies, black holes, dark energy, and the origin of the elements necessary for life.”
The telescope launched into space in 1999 aboard the space shuttle and currently works at an altitude as high as 86,500 miles (139,000 miles). It is named after Indian-American astrophysicist Subrahmanyan Chandrasekhar; the name “Chandra” also means “moon” or “luminous” in Sanskrit.
And there’s more to come. You can learn more about Chandra’s greatest discoveries and its future in this Google+ Hangout, which will start at 3 p.m. EDT (7 p.m. EDT) at this link.
Interior of Jupiter. Image Credit: NASA / R. J. Hall
It’s likely that Jupiter-like planets’ origins root back to either the rapid collapse of a dense cloud or small rocky cores that glom together until the body is massive enough to accrete a gaseous envelope.
Although these two competing theories are both viable, astronomers have, for the first time, seen the latter “core accretion” theory in action. By studying the exoplanet’s host star they’ve shed light on the composition of the planet’s rocky core.
“Our results show that the formation of giant planets, as well as terrestrial planets like our own Earth, leaves subtle signatures in stellar atmospheres”, said lead author and PhD student Marcelo Tucci Maia from University of São Paulo, Brazil, in a press release.
Maia and colleagues pointed the 3.5-meter Canada-France-Hawaii Telescope toward the constellation Cygnus, in order to take a closer look at two Sun-like stars in the distant 16 Cyg triple-star system. Both stars, having formed together from the same gaseous disk over 10 billion years ago and having reached the same mass, are nearly solar twins.
But only one star, 16 Cygni B, hosts a giant planet. By decomposing the light from the two stars into their wavelengths and looking at the difference between the two stars, the team was able to detect signatures left from the planet formation process on 16 Cygni B.
It’s the perfect laboratory to study the formation of giant planets.
Difference in chemical composition between the stars 16 Cyg A and 16 Cyg B, versus the condensation temperature of the elements in the proto-planetary nebula. Image Credit: M. Tucci Maia, J. Meléndez, I. Ramírez.
Maia and colleagues found that the star 16 Cygni A is enhanced in all chemical elements relative to 16 Cygni B. Hence, the metals removed from 16 Cygni B were most likely removed from the protoplanetary disk in order to form the planet.
On top of the overall deficiency in all elements, 16 Cygni B has an added deficiency in the refractory elements — those with high condensation temperatures that form dust grains more easily — such as iron, aluminum, nickel, magnesium, scandium, and silicon. This helps verify what astronomers have expected all along: rocky cores are rich in refractory elements.
The team was able to decipher that these missing elements likely created a rocky core with a mass of about 1.5 to 6 Earth masses, which is similar to the estimate of Jupiter’s core.
“16 Cyg is a remarkable system, but certainly not unique,” said coauthor Ivan Ramírez from the University of Texas. “It is special because it is nearby; however, there are many other binary stars with twin components on which this experiment could be performed. This could help us find planet-host stars in binaries in a much more straightforward manner compared to all other planet-finding techniques we have available today.”
The results were accepted for publication in The Astrophysical Journal Letters and are available online.
There’s no doubt the term “Earth-like” is a bit of a misnomer. It requires only that a planet is both Earth-size (less than 1.25 times Earth’s girth and less than twice Earth’s mass) and circles its host star within the habitable zone.
But defining a “Sun-like” star may be just as difficult. A solar twin should have a temperature, mass, age, radius, metallicity, and spectral type similar to the Sun. Although measuring most of these factors isn’t easy, aging a star is extremely difficult, and astronomers tend to ignore it when concluding if a star is Sun-like or not.
This is less than ideal, given that our Sun and all stars change over time. Thankfully a technique — gyrochronology — is allowing astronomers to measure stellar ages based only on spin and find true solar analogues.
“We have found stars with properties that are close enough to those of the Sun that we can call them ‘solar twins,'” said lead author Jose Dias do Nascimento from the Harvard-Smithsonian Center for Astrophysics (CfA) in a press release.
do Nascimento and colleagues measured the spin of 75 stars by looking for changes in brightness caused by dark star spots, rotating in and out of view. Although this difference is minute, clocking in at a few percent or less, NASA’s Kepler spacecraft excels at extracting such small changes in brightness.
On average, the sampled stars spin once every 19 days, compared to the 25-day rotation period of the Sun. This makes most of the stars slightly younger than the Sun, as younger stars spin faster than older ones.
The relationship between stellar spin and age was determined in previous research by Soren Meibom (CfA) and colleagues, who measured the rotation rates for stars in a one-billion-year-old cluster. Since the stars already had a known age, the team could measure their spin rates and calibrate the previous relationship.
Using this method, do Nascimento and colleagues found 22 true solar analogues within their data set of 75 stars.
“With solar twins we can study the past, present, and future of stars like our Sun,” said do Nascimento. “Consequently, we can predict how planetary systems like our solar system will be affected by the evolution of their central stars.”
The results were accepted for publication in The Astrophysical Journal Letters and are available online.
In this new Hubble image shows two galaxies (yellow, center) from the cluster SDSS J1531+3414 have been found to be merging into one and a "chain" of young stellar super-clusters are seen winding around the galaxies'?? nuclei. The galaxies are surrounded by an egg-shaped blue ring caused by the immense gravity of the cluster bending light from other galaxies beyond it. Credit: NASA/ESA/Grant Tremblay
On a summer night, high above our heads, where the Northern Crown and Herdsman meet, a titanic new galaxy is being born 4.5 billion light years away. You and I can’t see it, but astronomers using the Hubble Space Telescope released photographs today showing the merger of two enormous elliptical galaxies into a future heavyweight adorned with a dazzling string of super-sized star clusters.
The two giants, each about 330,000 light years across or more than three times the size of the Milky Way, are members of a large cluster of galaxies called SDSS J1531+3414. They’ve strayed into each other’s paths and are now helpless against the attractive force of gravity which pulls them ever closer.
A few examples of merging galaxies. NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), K. Noll (STScI), and J. Westphal (Caltech)
Galactic mergers are violent events that strip gas, dust and stars away from the galaxies involved and can alter their appearances dramatically, forming large gaseous tails, glowing rings, and warped galactic disks. Stars on the other hand, like so many pinpoints in relatively empty space, pass by one another and rarely collide.
Elliptical galaxies get their name from their oval and spheroidal shapes. They lack the spiral arms, rich reserves of dust and gas and pizza-like flatness that give spiral galaxies like Andromeda and the Milky Way their multi-faceted character. Ellipticals, although incredibly rich in stars and globular clusters, generally appear featureless.
The differences between elliptical and spiral galaxies is easy to see. M87 at left and M74, both photographed with the Hubble Space Telescope. What look like stars around M87 are really globular star clusters. Credit: NASA/ESA
But these two monster ellipticals appear to be different. Unlike their gas-starved brothers and sisters, they’re rich enough in the stuff needed to induce star formation. Take a look at that string of blue blobs stretching across the center – astronomers call it a great example of ‘beads on a string’ star formation. The knotted rope of gaseous filaments with bright patches of new star clusters stems from the same physics which causes rain or water from a faucet to fall in droplets instead of streams. In the case of water, surface tension makes water ‘snap’ into individual droplets; with clouds of galactic gas, gravity is the great congealer.
Close up of the two elliptical galaxies undergoing a merger. The blue blobs are giant star clusters forming from gas colliding and collapsing into stars during the merger. Click to read the scientific paper on the topic. Credit: NASA/ESA/Grant Tremblay
Nineteen compact clumps of young stars make up the length of this ‘string’, woven together with narrow filaments of hydrogen gas. The star formation spans 100,000 light years, about the size of our galaxy, the Milky Way. Astronomers still aren’t sure if the gas comes directly from the galaxies or has condensed like rain from X-ray-hot halos of gas surrounding both giants.
The blue arcs framing the merger have to do with the galaxy cluster’s enormous gravity, which warps the fabric of space like a lens, bending and focusing the light of more distant background galaxies into curvy strands of blue light. Each represents a highly distorted image of a real object.
Simulation of the Milky Way-Andromeda collision 4 billion years from now
Four billion years from now, Milky Way residents will experience a merger of our own when the Andromeda Galaxy, which has been heading our direction at 300,000 mph for millions of years, arrives on our doorstep. After a few do-si-dos the two galaxies will swallow one another up to form a much larger whirling dervish that some have already dubbed ‘Milkomeda’. Come that day, perhaps our combined galaxies will don a string a blue pearls too.
It’s one of the most iconic images of the modern Space Age. In 1995, the Hubble Space Telescope team released an image of towering columns of gas and dust that contained newborn stars in the midst of formation. Dubbed the “Pillars of Creation,” these light-years long tendrils captivated the public imagination and now grace everything from screensavers to coffee mugs. This is a cosmic portrait of our possible past, and the essence of the universe giving birth to new stars and worlds in action.
Now, a study out on Thursday from the 2014 National Astronomy Meeting of the Royal Astronomical Society has shed new light on just how these pillars may have formed. The announcement comes out of Cardiff University, where astronomer Scott Balfour has run computer simulations that closely model the evolution and the outcome of what’s been observed by the Hubble Space Telescope.
The ‘Pillars’ lie in the Eagle Nebula, also known as Messier 16 (M16), which is situated in the constellation Serpens about 7,000 light years distant. The pillars themselves have formed as intense radiation from young massive stars just beginning to shine erode and sculpt the immense columns.
The location of Messier 16 and the Pillars of Creation in the night sky. Credit: Stellarium.
But as is often the case in early stellar evolution, having massive siblings nearby is bad news for fledgling stars. Such large stars are of the O-type variety, and are more than 16 times as massive as our own Sun. Alnitak in Orion’s belt and the stars of the Trapezium in the Orion Nebula are examples of large O-type stars that can be found in the night sky. But such stars have a “burn fast and die young” credo when it comes to their take on nuclear fusion, spending mere millions of years along the Main Sequence of the Hertzsprung Russell diagram before promptly going supernova. Contrast this with a main sequence life expectancy of 10 billion years for our Sun, and life spans measured in the trillions of years — longer than the current age of the universe — for tiny red dwarf stars. The larger a star you are, the shorter your life span.
A capture from the simulation, showing a cross-section 25 by 25 light years square and 0.2 light years thick. The simulation shows how the O-type star “sculpts” its surroundings over the span of 1.6 million years, carving out, in some cases, the famous “pillars”. Credit: S. Balfour/ University of Cardiff.
Such O-Type stars also have surface temperatures at a scorching 30,000 degrees Celsius, contrasted with a relatively ‘chilly’ 5,500 degree Celsius surface temperature for our Sun.
This also results in a prodigious output in energetic ultraviolet radiation by O-type stars, along with a blustery solar wind. This carves out massive bubbles in a typical stellar nursery, and while it may be bad news for planets and stars attempting to form nearby any such tempestuous stars, this wind can also compress and energize colder regions of gas and dust farther out and serve to trigger another round of star formation. Ironically, such stars are thus “cradle robbers” when it comes to potential stellar and planetary formation AND promoters of new star birth.
In his study, Scott looked at the way gas and dust would form in a typical proto-solar nebula over the span of 1.6 million years. Running the simulation over the span of several weeks, the model started with a massive O-type star that formed out of an initial collapsing smooth cloud of gas.
That’s not bad, a simulation where 1 week equals a few hundred million years…
As expected, said massive star did indeed carve out a spherical bubble given the initial conditions. But Scott also found something special: the interactions of the stellar winds with the local gas was much more complex than anticipated, with three basic results: either the bubble continued to expand unimpeded, the front would expand, contract slightly and then become a stationary barrier, or finally, it would expand and then eventually collapse back in on itself back to the source.
The study was notable because it’s only in the second circumstance that the situation is favorable for a new round of star formation that is seen in the Pillars of Creation.
“If I’m right, it means that O-type and other massive stars play a much more complex role than we previously thought in nursing a new generation of stellar siblings to life,” Scott said in a recent press release. “The model neatly produces exactly the same kind of structures seen by astronomers in the classic 1995 image, vindicating the idea that giant O-type stars have a major effect in sculpting their surroundings.”
Such visions as the Pillars of Creation give us a snapshot of a specific stage in stellar evolution and give us a chance to study what we may have looked like, just over four billion years ago. And as simulations such as those announced in this week’s study become more refined, we’ll be able to use them as a predictor and offer a prognosis for a prospective stellar nebula and gain further insight into the secret early lives of stars.
The band of the Milky Way stretches from Cygnus (left) to the Sagittarius in this wide-angle, guided photo. Credit: Bob King
Look east on a dark June night and you’ll get a face full of stars. Billions of them. With the moon now out of the sky for a couple weeks, the summer Milky Way is putting on a grand show. Some of its members are brilliant like Vega, Deneb and Altair in the Summer Triangle, but most are so far away their weak light blends into a hazy, luminous band that stretches the sky from northeast to southwest. Ever wonder just where in the galaxy you’re looking on a summer night? Down which spiral arm your gaze takes you?
Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. HurtTwo different perspectives on our galaxy help us better understand its shape. A face-on artist’s view at left reveals the core, spiral arms and the sun’s position. At right, we see an edge-on perspective photographed by the Cosmic Background Explorer probe. Because the sun and planets orbit in the galaxy’s plane, we’re ‘stuck’ with an edge-on view until we build a fast-enough rocket to take us above our galactic home. Credit: NASA/JPL et. all (left) and NASA
Because all stars are too far away for us to perceive depth, they appear pasted on the sky in two dimensions. We know this is only an illusion. Stars shine from every corner of the galaxy, congregating in its bar-shaped core, outer halo and along its shapely spiral arms. The trick is using your mind’s eye to see them that way.
Employing optical, infrared and radio telescopes, astronomers have mapped the broad outlines of the home galaxy, placing the sun in a minor spiral arm called the Orion or Local Arm some 26,000 light years from the galactic center. Spiral arms are named for the constellation(s) in which they appear. The grand Perseus Arm unfurls beyond our local whorl and beyond it, the Outer Arm. Peering in the direction of the galaxy’s core we first encounter the Sagittarius Arm, home to sumptuous star clusters and nebulae that make Sagittarius a favorite hunting ground for amateur astronomers.
Further in lies the massive Scutum-Centaurus Arm and finally the inner Norma Arm. Astronomers still disagree on the number of major arms and even their names, but the basic outline of the galaxy will serve as our foundation. With it, we can look out on a dark summer night at the Milky Way band and get a sense where we are in this magnificent celestial pinwheel.
The Milky Way band arches across the east and south as seen about 11:30 p.m. in mid-late June. The center of the galaxy is in the direction of the constellation Sagittarius. The dark ‘rift’ that appears to cleave the Milky Way in two is formed of clouds of interstellar dust that blocks the light of stars beyond it. Stellarium
We’ll start with the band of the Milky Way itself. Its ribbon-like form reflects the galaxy’s flattened, lens-like profile shown in the edge-on illustration above. The sun and planets are located within the galaxy’s plane (near the equator) where the stars are concentrated in a flattened disk some 100,000 light years across. When we look into the galaxy’s plane, billions of stars pile up across thousands of light years to create a narrow band of light we call the Milky Way. The same term is applied to the galaxy as a whole.
Since the average thickness of the galaxy is only about 1,000 light years, if you look above or below the band, your gaze penetrates a relatively short distance – and fewer stars – until entering intergalactic (starless) space. That why the rest of the sky outside of the Milky Way band has so few stars compared to the hordes we see within the band.
Here’s the galactic big picture showing the outline of the galaxy with constellations added. In this edge-on view, we see that the summertime Milky Way from Cassiopeia to Sagittarius includes the central bulge (in the direction of Sagittarius) and a hefty portion of one side of the flattened disk:
The outline of the Milky Way viewed edge-on is shown in gray. The yellow box includes the summer portion of the Milky Way from Cassiopeia to Scorpius with a red dot marking the galaxy’s center. This is the section we see crossing the eastern sky in June. Click to enlarge. Credit: Richard Powell with additions by the author
If you enlarge the map, you’ll see lines of galactic latitude and longitude much like those used on Earth but applied to the entire galaxy. Latitude ranges from +90 degrees at the North Galactic Pole to -90 at the South Galactic Pole. Likewise for longitude. 0 degrees latitude, o degrees longitude marks the galactic center. The summer Milky Way band extends from about longitude 340 degrees in Scorpius to 110 in Cassiopeia.
Now that we know what section of the Milky Way we peer into this time of year, let’s take an imaginary rocket journey and see it all from above:
Viewed from above, we can now see that our gaze (red arrows) reaches down the Perseus Arm (toward the constellation Cygnus) and across the Sagittarius and Scutum-Centaurus arms (toward the constellations Scutum, Sagittarius and Ophiuchus) and directly into the central bar. Interstellar dust obscures much of the center of the galaxy. Blue arrows show the direction we face during the winter months. Credit: NASA et. all with additions by the author.
Wow! The hazy arch of June’s Milky Way takes in a lot of galactic real estate. A casual look on a dark night takes us from Cassiopeia in the outer Perseus Arm across Cygnus in our Local Arm clear over to Sagittarius, the next arm in. Interstellar dust deposited by supernovae and other evolved stars obscures much of the center of the galaxy. If we could vacuum it all up, the galaxy’s center – where so many stars are concentrated – would be bright enough to cast shadows.
A view showing the summer Milky Way from mid-northern latitudes with three prominent constellations and the spiral arms we peer into when we face them. Stellarium
Here and there, there are windows or clearings in the dust cover that allow us to see star clouds in the Scutum-Centaurus and Norma Arms. In the map, I’ve also shown the section of Milky Way we face in winter. If you’ve ever compared the winter Milky Way band to the summer’s you’ve noticed it’s much fainter. I think you can see the reason why. In winter, we face away from the galaxy’s core and out into the fringes where the stars are sparser.
Look up the next dark night and contemplate the grand architecture of our home galaxy. If you close your eyes, you might almost feel it spinning.
Hubble Space Telescope picture of galaxy NGC 3081. Credit: ESA/Hubble & NASA; acknowledgement: R. Buta (University of Alabama)
Let’s just casually look at this image of a galaxy 86 million light-years away from us. In the center of this incredible image is a bright loop that you can see surrounding the heart of the galaxy. That is where stars are being born, say the scientists behind this new Hubble Space Telescope image.
“Compared to other spiral galaxies, it looks a little different,” NASA stated. “The galaxy’s barred spiral center is surrounded by a bright loop known as a resonance ring. This ring is full of bright clusters and bursts of new star formation, and frames the supermassive black hole thought to be lurking within NGC 3081 — which glows brightly as it hungrily gobbles up in-falling material.”
A “resonance ring” refers to an area where gravity causes gas to stick around in certain areas, and can be the result of a ring (like you see in NGC 3081) or close-by objects with a lot of gravity. Scientists added that NGC 3081, which is in the constellation Hydra or the Sea Serpent, is just one of many examples of barred galaxies with this type of resonance.
By the way, this image is a combination of several types of light: optical, infrared and ultraviolet.
A new study by Brazilian astronomers details the discoveries of some 300 new star clusters using the WISE space telescope (credit NASA/JPL-Caltech/UCLA).
Brazilian astronomers have discovered some 300+ star clusters that were largely overlooked owing to sizable obscuration by dust. The astronomers, from the Universidade Federal do Rio Grande do Sul, used data obtained by NASA’s WISE (Wide-Field Infrared Survey Explorer) space telescope to detect the clusters.
“WISE is a powerful tool to probe … young clusters throughout the Galaxy”, remarked the group. The clusters discovered were previously overlooked because the constituent stars are deeply embedded in their parent molecular cloud, and are encompassed by dust. Stars and star clusters can emerge from such environments.
The group added that, “The present catalog of new clusters will certainly become a major source for future studies of star cluster formation.” Indeed, WISE is well-suited to identify new stars and their host clusters because infrared radiation is less sensitive to dust obscuration. The infrared part of the electromagnetic spectrum is sampled by WISE.
An optical (DSS) and infrared (WISE) image of the same field. A cluster of young stars is not apparent in the optical (left) image owing to obscuration by dust. However, a young star cluster is readily apparent in the right image because dust obscuration is significantly less at infrared wavelengths. A new study by a team of astronomers highlights the discovery of numerous star clusters using WISE data (image credit: DSS/NASA/IPAC and assembly by D. Majaess).
Historically, new star clusters were often identified while inspecting photographic plates imaged at (or near) visible wavelengths (i.e., the same wavelengths sampled by the eye). Young embedded clusters were consequently under-sampled since the amount of obscuration by dust is wavelength dependent. As indicated in the figure above, the infrared observations penetrate the dust by comparison to optical observations.
The latest generation of infrared survey telescopes (e.g., Spitzer and WISE) are thus excellent instruments for detecting clusters embedded in their parent cloud, or hidden from detection because of dust lying along the sight-line. The team notes that, “The Galaxy appears to contain 100000 open clusters, but only some 2000 have established astrophysical parameters.” It is hoped that continued investigations using WISE and Spitzer will help astronomers minimize that gap.
An infrared image of N103B, the remainders of a supernova that exploded about 1,000 years ago in the Large Magellanic Cloud, which is one of the closest galaxies to the Milky Way. Credit: NASA/JPL-Caltech/Goddard
It might be a bad idea to get close to dead stars. Like a White Walker from Game of Thrones, this “cosmic zombie” white dwarf star was dangerous even though it was just a corpse of a star like our own. The result from this violence is still visible in the Spitzer Space Telescope picture you see above.
Astronomers believe the giant star was shedding material (a common phenomenon in older stars), which fell on to the white dwarf star. As the gas built up on the white dwarf over time, the mass became unstable and the dwarf exploded. What’s left is still lying in a pool of gas about 160,000 light-years away from us.
“It’s kind of like being a detective,” stated Brian Williams of NASA’s Goddard Space Flight Center, who led the research. “We look for clues in the remains to try to figure out what happened, even though we weren’t there to see it.”
This explosion in the Large Magellanic Cloud — one of the closest satellite galaxies to Earth — is known as a Type 1a supernova, but it’s a rare breed of that kind. Type 1as are best known as “standard candles” because their explosions have a consistent luminosity. Knowing how luminous the supernova type is allows astronomers to estimate distance based on its apparent brightness; the fainter the supernova is, the further away it is.
Most Type 1as happen when two orbiting white dwarfs smash into each other, but this scenario is more akin to something that Earthlings saw in 1604. Informally called Kepler’s supernova, because it was discovered by astronomer Johannes Kepler, astronomers believe this arose from a red giant and white dwarf interaction. The evidence left for this conclusion showed the supernova leftovers embedded in dust and gas.
Investigators have submitted their results to the Astrophysical Journal.
