supernova Archives

February 19, 2013December 23, 2015 by Bob King

Bright New Supernova Shines in Southern Skies

New supernova 2013aa, discovered by Stu Parker on February 13, 2013, is southwest of the spiral galaxy NGC 5643 in the southern constellation Lupus. This photo was taken three days later. Credit: Joseph Brimacombe

I live in the frozen north by choice, but occasionally I yearn for warmer places like Tucson and Key West. These feelings usually start in late February, when after nearly four months of winter, the season feels endless. Today I wish I could head down south for another reason – to see a very bright supernova in a galaxy in Lupus.

SN 2013aa popped off in the barred spiral galaxy NGC 5643 in the constellation Lupus the Wolf 34 million years ago, but no one knew its light was wiggling its way across the cosmos to Earth until New Zealand amateur astronomer Stu Parker nailed it during one of his regular supernovae hunts. Parker recorded it on Feb. 13, 2013. Since it was so far from the galaxy, he thought at first it was a hot pixel (electronic artifact) or an asteroid. Another look at the galaxy 5 minutes later confirmed it was really there.

Good thing. It turned out upon confirmation to be the brightest supernova he and his band of supernova hunters had ever discovered.

Stu is a member of a 6-man amateur supernova search team from Australia and New Zealand called BOSS (Backyard Observatory Supernova Search). They’ve been working together since 2008 with the goal of searching for and reporting supernovae in the southern sky. When a member finds a candidate, they contact profession astronomers who follow up using large telescopes. To date the group has found 56 supernovae with Stu discovering or co-discovering 45 of them!

Map showing the sky looking south around 5 a.m. local time from Tuscon, Arizona. The new supernova in galaxy NGC 5643 is low in the southern sky before dawn for observers in the southern U.S. and points south. Created with Stellarium

From the northern U.S., much of Lupus and especially the supernova never make it above the horizon, but from about 35 degrees north and points south, SN 2013aa is fair game. The “new star” lies southwest of the core of galaxy NGC 5643, which shines at magnitude 10, bright enough to see in a 6-inch telescope from a dark sky. The supernovae is still climbing in brightness and today gleams at about 11.6 magnitude – no problem in that 6-inch if you’re equipped with a good map or photo to help get you there.

In this annotated version of the Joseph Brimacombe's photo, I've suggested a straightforward "star hop" from the galaxy's nucleus to the supernova. — In this annotated version of the Joseph Brimacombe’s photo, I’ve suggested a straightforward “star hop” from the galaxy’s core to 2013aa using brighter foreground stars.

Based on the study of 2013aa’s light, astronomers have classified it as Type Ia. Before the explosion, the star was a white dwarf, a superdense, planet-sized object with the mass of the sun. Tiny but mighty, the white dwarf’s powerful gravity pulled material from a nearby companion star down to its surface. When a dwarf puts on enough pounds to exceed 1.4 times the sun’s mass, the extra material increases the pressure and temperature of the core and the star burns explosively.

In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to collapse and then explosion. — In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to runaway burning and a catastrophic explosion that obliterates the star.

The energy released increases the star’s brightness to 5 billion times that of the sun. Matter from the blast streaks into space at speeds of 3,000-12,000 miles per second. Yes, this is a BIG deal and one of the most energetic events the universe has to offer. No wonder amateurs like myself can’t get enough of them.

NGC 5643 is best placed in the southern sky around 5 a.m. local time. From Lexington, KY. (latitude 38 degrees N.) it’s only 8 degrees high or slightly less than one fist held at arm’s length. Tuscon’s better at 14 degrees and Key West (latitude 25 N) best at 21. Farther south, your views will continue to improve. And the pleasant temperatures can’t hurt either.

You can start with the bright pair of Saturn and Spica midway up in the southern sky. Look about two outstretched fists below them to find Theta Centauri and from there “three fingers” to the lower left (southeast) to Eta Centauri. The galaxy is about 1 1/2 degrees southwest of Eta. The supernova will look like an 11 1/2 magnitude star 74″ west and 180″ south of the galaxy’s bright core. Use the annotated photo to help guide you straight to it.

To keep track of the 2013aa’s progress as well as view many more photos, I highly recommend David Bishop’s Latest Supernovae site.

February 15, 2013December 23, 2015 by Tammy Plotner

Supernovae Seed Universe With Cosmic Rays

In a wave of media releases, the latest studies performed by NASA’s Fermi Gamma-ray Space Telescope are lighting up the world of particle astrophysics with the news of how supernovae could be the progenitor of cosmic rays. These subatomic particles are mainly protons, cruising along through space at nearly the speed of light. The rest are electrons and atomic nuclei. When they meet up with a magnetic field, their paths change like a bumper car in an amusement park – but there’s nothing amusing about not knowing their origins. Now, four years of hard work done by scientists at the Kavli Institute for Particle Astrophysics and Cosmology at the Department of Energy’s (DOE) SLAC National Accelerator Laboratory has paid off. There is evidence of how cosmic rays are born.

“The energies of these protons are far beyond what the most powerful particle colliders on Earth can produce,” said Stefan Funk, astrophysicist with the Kavli Institute and Stanford University, who led the analysis. “In the last century we’ve learned a lot about cosmic rays as they arrive here. We’ve even had strong suspicions about the source of their acceleration, but we haven’t had unambiguous evidence to back them up until recently.”

Until now, scientists weren’t clear on some particulars – such as what atomic particles could be responsible for the emissions from interstellar gas. To aid their research, they took a very close look at a pair of gamma ray emitting supernova remnants – known as IC 443 and W44. Why the discrepancy? In this case gamma rays share similar energies with cosmic ray protons and electrons. To set them apart, researchers have uncovered the neutral pion, the product of cosmic ray protons impacting normal protons. When this happens, the pion rapidly decays into a set of gamma rays, leaving a signature decline – one which provides proof in the form of protons. Created in a process known as Fermi Acceleration, the protons remain captive in the rapidly moving shock front of the supernova and aren’t affected by magnetic fields. Thanks to this property, the astronomers were able to trace them back directly to their source.

“The discovery is the smoking gun that these two supernova remnants are producing accelerated protons,” said lead researcher Stefan Funk, an astrophysicist with the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California. “Now we can work to better understand how they manage this feat and determine if the process is common to all remnants where we see gamma-ray emission.”

Are they little speedsters? You betcha. Every time the particle passes across the shock front, it gains about 1% more speed – eventually enough to break free as cosmic ray. “Astronauts have documented that they actually see flashes of light associated with cosmic rays,” Funk noted. “It’s one of the reasons I admire their bravery – the environment out there is really quite tough.” The next step in this research, Funk added, is to understand the exact details of the acceleration mechanism and also the maximum energies to which supernova remnants can accelerate protons.

However, the studies don’t end there. More new evidence of supernovae remnants acting like particle accelerators emerged during careful observational analysis by the Serbian astronomer Sladjana Nikolic (Max Planck Institute for Astronomy). They took a look at the composition of the light. Nikolic explains: “This is the first time we were able to take a detailed look at the microphysics in and around the shock region. We found evidence for a precursor region directly in front of the shock, which is thought to be a prerequisite of cosmic ray production. Also, the precursor region is being heated in just the way one would expect if there were protons carrying away energy from the region directly behind the shock.”

Nikolic and her colleagues employed the spectrograph VIMOS at the European Southern Observatory’s Very Large Telescope in Chile to observe and document a short section of the shock front of the supernova SN 1006. This new technique is known as integral field spectroscopy – a first-time process which allows astronomers to thoroughly examine the composition of the light from the supernova remnant. Kevin Heng of the University of Bern, one of the supervisors of Nikolic’s doctoral work, says: “We are particularly proud of the fact that we managed to use integral field spectroscopy in a rather unorthodox way, since it is usually used for the study of high-redshift galaxies. In doing so, we achieved a level of precision that far exceeds all previous studies.”

It really is an intriguing time to be taking closer looks at supernovae remnants – especially in respect to cosmic rays. As Nikolic explains: “This was a pilot project. The emissions we observed from the supernova remnant are very, very faint compared to the usual target objects for this type of instrument. Now that we know what’s possible, it’s really exciting to think about follow-up projects.” Glenn van de Ven of the Max Planck Institute for Astronomy, Nikolic’s other co-supervisor and an expert in integral field spectroscopy, adds: “This kind of novel observational approach could well be the key to solving the puzzle of how cosmic rays are produced in supernova remnants.”

Kavli Institute Director Roger Blandford, who participated in the Fermi analysis, said, “It’s fitting that such a clear demonstration showing supernova remnants accelerate cosmic rays came as we celebrated the 100th anniversary of their discovery. It brings home how quickly our capabilities for discovery are advancing.”

Original Story Sources and Further Reading: Novel approach in hunt for cosmic particle accelerator, NASA’s Fermi Proves Supernova Remnants Produce Cosmic Rays, and Proof: Cosmic Rays Come from Exploding Stars.

December 18, 2012December 23, 2015 by Jason Major

One of the Largest Astronomical Images Ever Made

The northern portion of the Cygnus Loop, as seen in an enormous new panorama from the National Optical Astronomy Observatory (NOAO) and WIYN partners

Looking for a stunning new desktop image to wrap up the year? Try this: it’s an amazing panorama of the Cygnus Loop, a supernova remnant located 1,500 light-years away in the constellation (you guessed it) Cygnus. The full-size image, acquired with the wide-field Mosaic camera on the WIYN 0.9-meter telescope at Kitt Peak, Arizona, is a staggering 600 million pixels in size — over 1.68 gigabytes — making it one of the largest astronomical images ever made!

See the full image (and links to download larger versions) below:

2000-pixel-wide version of the full Cygnus Loop panorama

The entire structure of the Cygnus Loop, the gaseous remains of a supernova that occurred 5,000 – 10,000 years ago, covers an area nearly 45 times the size of the full Moon in the sky.

In the image, hydrogen alpha, sulphur, and oxygen ions correspond to the red, green, and blue color values, respectively.

“Images like this are amazing because they can remind you of the big picture and beauty that surrounds us.”

– Dr. Richard Cool, MMT Observatory

From the NOAO press release:

Astronomers estimate the supernova explosion that produced the nebula occurred between 5,000 to 10,000 years ago. First noted in 1784 by William Herschel, it is so large that its many parts have been catalogued as separate objects, including NGC 6992, NGC 6995 and IC 1340 along the eastern (left) side of the image, NGC 6974 and NGC 6979 near the top-center, and the Veil Nebula (NGC 6960) and Pickering’s Triangle along the western (right) edge. The bright star near the western edge of the image, known as 52 Cygnus, is not associated with the supernova.

“Often, astronomical research reduces images to dry tables of numerical information that we analyze in order to more deeply understand our universe,” said Dr. Richard Cool, astronomer at the MMT Observatory in Arizona, who originally obtained the images in 2003 while still a graduate student. “Images like this are amazing because they can remind you of the big picture and beauty that surrounds us.”

This incredible image demonstrates that even relatively small telescopes are capable of producing cutting-edge research, when equipped with modern cameras.

Got bandwidth to spare? Download the full-size 1686.5 MB TIFF image here, or find other versions on the NOAO page here.

Image Credit: T.A. Rector (University of Alaska Anchorage), Richard Cool (University of Arizona) and WIYN/NOAO/AURA/NSF. Inset image: original dome of the Kitt Peak 0.9-meter telescope. (NOAO/AURA/NSF)

December 8, 2012December 23, 2015 by Jason Major

X-ray Burst May Be the First Sign of a Supernova

GRB 080913, a distant supernova detected by Swift. This image merges the view through Swift’s UltraViolet and Optical Telescope, which shows bright stars, and its X-ray Telescope. Credit: NASA/Swift/Stefan Immler

The first moments of a massive star going supernova may be heralded by a blast of x-rays, detectable by space telescopes like Swift, which could then tell astronomers where to look for the full show in gamma rays and optical wavelengths. These findings come from the University of Leicester in the UK where a research team was surprised by the excess of thermal x-rays detected along with gamma ray bursts associated with supernovae.

“The most massive stars can be tens to a hundred times larger than the Sun,” said Dr. Rhaana Starling of the University of Leicester Department of Physics and Astronomy. “When one of these giants runs out of hydrogen gas it collapses catastrophically and explodes as a supernova, blowing off its outer layers which enrich the Universe.

“But this is no ordinary supernova; in the explosion narrowly confined streams of material are forced out of the poles of the star at almost the speed of light. These so-called relativistic jets give rise to brief flashes of energetic gamma-radiation called gamma-ray bursts, which are picked up by monitoring instruments in space, that in turn alert astronomers.”

Powerful gamma ray bursts — GRBs — emitted from supernovae can be detected by both ground-based observatories and NASA’s Swift telescope. Within seconds of detecting a burst (hence its name) Swift relays its location to ground stations, allowing both ground-based and space-based telescopes around the world the opportunity to observe the burst’s afterglow.

But the actual moment of the star’s collapse, when its collapsing core reacts with its surface, isn’t observed — it happens too quickly, too suddenly. If these “shock breakouts” are the source of the excess thermal x-rays (a.k.a. black body emission) that have been recently identified in Swift data, some of the galaxy’s most energetic supernovae could be pinpointed and witnessed at a much earlier moment in time — literally within the first seconds of their birth.

“This phenomenon is only seen during the first thousand seconds of an event, and it is challenging to distinguish it from X-ray emission solely from the gamma-ray burst jet,” Dr. Starling said. “That is why astronomers have not routinely observed this before, and only a small subset of the 700+ bursts we detect with Swift show it.”

More observations will be needed to determine if the thermal emissions are truly from the initial collapse of stars and not from the GRB jets themselves. Even if the x-rays are determined to be from the jets it will provide valuable insight to the structure of GRBs… “but the strong association with supernovae is tantalizing,” according to Dr. Starling.

Read more on the University of Leicester press release here, and see the team’s paper in the Nov. 28 online issue of the Monthly Notices of the Royal Astronomical Society here (Full PDF on arXiv.org here.)

Inset image: An artist’s rendering of the Swift spacecraft with a gamma-ray burst going off in the background. Credit: Spectrum Astro. Find out more about the Swift telescope’s instruments here.

November 27, 2012December 23, 2015 by Jason Major

Unraveling the Secrets of Type Ia Supernovae: a New Two-Minute Thesis

The folks over at PHD Comics have put together a new video in their Two-Minute Thesis series, this one featuring Ph.D candidate Or Graur of the University of Tel Aviv and the American Museum of Natural History discussing the secret lives — and deaths — of astronomers’ “standard candles” of universal distance, Type Ia supernovae.

Judging distances across intergalactic space isn’t easy, so in order to figure out how far away galaxies are astronomers have learned to use the light from Type Ia supernovae, which flare up with the brilliance of 5 billion Suns… and rather precisely so.

Type Ia supernovae are thought to be created from a pairing of two stars: one super-dense white dwarf which draws in material from a binary companion until a critical mass — about 40% more mass than the Sun – is reached. The overpacked white dwarf suddenly undergoes a rapid series of thermonuclear reactions and explodes in an incredibly bright outburst of material and energy.

But exactly what sorts of stellar pairs lead to Type Ia supernovae and how frequently they occur aren’t known, and that’s what Ph.D candidate Or Graur is aiming to learn more about.

“We don’t really know what kind of star it is that leads to these explosions, which is kind of embarrassing,” says Graur. “The companion star could be a regular star like our Sun, a red giant or supergiant, or another white dwarf.”

Because stars age at certain rates, by looking deeper into space with the Hubble and Subaru telescopes Graur hopes to determine how often and when in the Universe’s history Type Ia supernovae occur, and thus figure out what types of stars are most likely responsible.

“My rate measurements favor a second white dwarf as the binary companion,” Graur says, “but the issue is far from settled.”

Watch the video for the full story, and visit PHD TV and PHD Comics for more great science illustrations.

Video: PHDComics. Animation: Jorge Cham. Series Producer: Meg Rosenburg. Inset image: merging white dwarfs causing a Type Ia supernova. (NASA/CXC/M Weiss)

November 2, 2012April 26, 2016 by Nancy Atkinson

Rare Supernova Pair are Most Distant Ever

High-resolution simulation of a galaxy hosting a super-luminous supernova and its chaotic environment in the early Universe. Credit: Adrian Malec and Marie Martig (Swinburne University)

Some of the earliest stars were massive and short-lived, destined to end their lives in huge explosions. Astronomers have detected some of the earliest and most distant of these exploding stars, called ‘super-luminous’ supernovae — stellar explosions 10–100 times brighter than other supernova types. The duo sets a record for the most distant supernova yet detected, and offers clues about the very early Universe.

“The light of these supernovae contains detailed information about the infancy of the Universe, at a time when some of the first stars are still condensing out of the hydrogen and helium formed by the Big Bang,” said Dr. Jeffrey Cooke, an astrophysicist from Swinburne University of Technology in Australia, whose team made the discovery.

The team used a combination of data from the Canada-France-Hawaii Telescope and the Keck 1 Telescope, both located in Hawaii.

“The type of supernovae we’ve found are extremely rare,” Cooke said. “In fact, only one has been discovered prior to our work. This particular type of supernova results from the death of a very massive star (about 100 – 250 times the mass of our Sun) and explodes in a completely different way compared to other supernovae. Discovering and studying these events provides us with observational examples to better understand them and the chemicals they eject into the Universe when they die.”

Super-luminous supernovae were discovered only a few years ago, and are rare in the nearby Universe. Their origins are not well understood, but a small subset of them are thought to occur when extremely massive stars, 150 to 250 times more massive than our Sun, undergo a nuclear explosion triggered by the conversion of photons into electron-positron pairs. This process is completely different compared to all other types of supernovae. Such events are expected to have occurred more frequently in the early Universe, when massive stars were more common.

This, and the extreme brightness of these events, encouraged Cooke and colleagues to search for super-luminous supernovae at redshifts, z, greater than 2, when the Universe was less than one-quarter of its present age.

“We used LRIS (Low Resolution Imaging Spectrometer) on Keck I to get the deep spectroscopy to confirm the host redshifts and to search for late-time emission from the supernovae,” Cooke said. “The initial detections were found in the CFHT Legacy Survey Deep fields. The light from the supernovae arrived here on Earth 4 to 6 years ago. To confirm their distances, we need to get a spectrum of their host galaxies which are very faint because of their extreme distance. The large aperture of Keck and the high sensitivity of LRIS made this possible. In addition, some supernovae have bright enough emission features that persist for years after they explode. The deep Keck spectroscopy is able to detect these lines as a further means of confirmation and study.”

Cooke and co-workers searched through a large volume of the Universe at z greater than or equal to 2, and found two super-luminous supernovae, at redshifts of 2.05 and 3.90 — breaking the previous supernova redshift record of 2.36, and implying a production rate of super-luminous supernovae at these redshifts at least 10 times higher than in the nearby Universe. Although the spectra of these two objects make it unlikely that their progenitors were among the first generation of stars, the present results suggest that detection of those stars may not be far from our grasp.

Detecting the first stars allows us much greater understanding of the first stars in the Universe, Cooke said.

“Shortly after the Big Bang, there was only hydrogen and helium in the Universe,” he said. “All the other elements that we see around us today, such as carbon, oxygen, iron, and silicon, were manufactured in the cores of stars or during supernova explosions. The first stars to form after the Big Bang laid the framework for the long process of enriching the Universe that eventually produced the diverse set of galaxies, stars, and planets we see around us today. Our discoveries probe an early time in the Universe that overlaps with the time we expect to see the first stars.”

Sources: Keck Observatory, Nature

October 18, 2012December 23, 2015 by Jenny Winder

Integral: Ten Years Tracking Extreme Radiation Across the Universe

Caption: Artist’s impression of ESA’s orbiting gamma-ray observatory Integral. Image credit: ESA

Integral, ESA’s International Gamma-Ray Astrophysics Laboratory launched ten years ago this week. This is a good time to look back at some of the highlights of the mission’s first decade and forward to its future, to study at the details of the most sensitive, accurate, and advanced gamma-ray observatory ever launched. But the mission has also had some recent exciting research of a supernova remnant.

Integral is a truly international mission with the participation of all member states of ESA and United States, Russia, the Czech Republic, and Poland. It launched from Baikonur, Kazakhstan on October 17th 2002. It was the first space observatory to simultaneously observe objects in gamma rays, X-rays, and visible light. Gamma rays from space can only be detected above Earth’s atmosphere so Integral circles the Earth in a highly elliptical orbit once every three days, spending most of its time at an altitude over 60 000 kilometres – well outside the Earth’s radiation belts, to avoid interference from background radiation effects. It can detect radiation from events far away and from the processes that shape the Universe. Its principal targets are gamma-ray bursts, supernova explosions, and regions in the Universe thought to contain black holes.

5 metres high and more than 4 tonnes in weight Integral has two main parts. The service module is the lower part of the satellite which contains all spacecraft subsystems, required to support the mission: the satellite systems, including solar power generation, power conditioning and control, data handling, telecommunications and thermal, attitude and orbit control. The payload module is mounted on the service module and carries the scientific instruments. It weighs 2 tonnes, making it the heaviest ever placed in orbit by ESA, due to detectors’ large area needed to capture sparse and penetrating gamma rays and to shield the detectors from background radiation in order to make them sensitive. There are two main instruments detecting gamma rays. An imager producing some of the sharpest gamma-ray images and a spectrometer that gauges gamma-ray energies very precisely. Two other instruments, an X-ray monitor and an optical camera, help to identify the gamma-ray sources.

During its extended ten year mission Integral has has charted in extensive detail the central region of our Milky Way, the Galactic Bulge, rich in variable high-energy X-ray and gamma-ray sources. The spacecraft has mapped, for the first time, the entire sky at the specific energy produced by the annihilation of electrons with their positron anti-particles. According to the gamma-ray emission seen by Integral, some 15 million trillion trillion trillion pairs of electrons and positrons are being annihilated every second near the Galactic Centre, that is over six thousand times the luminosity of our Sun.

A black-hole binary, Cygnus X-1, is currently in the process of ripping a companion star to pieces and gorging on its gas. Studying this extremely hot matter just a millisecond before it plunges into the jaws of the black hole, Integral has discovered that some of it might be escaping along structured magnetic field lines. By studying the alignment of the waves of high-energy radiation originating from the Crab Nebula, Integral found that the radiation is strongly aligned with the rotation axis of the pulsar. This implies that a significant fraction of the particles generating the intense radiation must originate from an extremely organised structure very close to the pulsar, perhaps even directly from the powerful jets beaming out from the spinning stellar core.

Just today ESA reported that Integral has made the first direct detection of radioactive titanium associated with supernova remnant 1987A. Supernova 1987A, located in the Large Magellanic Cloud, was close enough to be seen by the naked eye in February 1987, when its light first reached Earth. Supernovae can shine as brightly as entire galaxies for a brief time due to the enormous amount of energy released in the explosion, but after the initial flash has faded, the total luminosity comes from the natural decay of radioactive elements produced in the explosion. The radioactive decay might have been powering the glowing remnant around Supernova 1987A for the last 20 years.

During the peak of the explosion elements from oxygen to calcium were detected, which represent the outer layers of the ejecta. Soon after, signatures of the material from the inner layers could be seen in the radioactive decay of nickel-56 to cobalt-56, and its subsequent decay to iron-56. Now, after more than 1000 hours of observation by Integral, high-energy X-rays from radioactive titanium-44 in supernova remnant 1987A have been detected for the first time. It is estimated that the total mass of titanium-44 produced just after the core collapse of SN1987A’s progenitor star amounted to 0.03% of the mass of our own Sun. This is close to the upper limit of theoretical predictions and nearly twice the amount seen in supernova remnant Cas A, the only other remnant where titanium-44 has been detected. It is thought both Cas A and SN1987A may be exceptional cases

Christoph Winkler, ESA’s Integral Project Scientist says “Future science with Integral might include the characterisation of high-energy radiation from a supernova explosion within our Milky Way, an event that is long overdue.”

Find out more about Integral here
and about Integral’s study of Supernova 1987A here

August 27, 2012December 23, 2015 by Jason Major

A New Species of Type Ia Supernova?

Artist’s conception of a binary star system that produces recurrent novae, and ultimately, the supernova PTF 11kx. (Credit: Romano Corradi and the Instituto de Astrofísica de Canarias)

Although they have been used as the “standard candles” of cosmic distance measurement for decades, Type Ia supernovae can result from different kinds of star systems, according to recent observations conducted by the Palomar Transient Factory team at California’s Berkeley Lab.

Judging distances across intergalactic space from here on Earth isn’t easy. Within the Milky Way — and even nearby galaxies — the light emitted by regularly pulsating stars (called Cepheid variables) can be used to determine how far away a region in space is. Outside of our own local group of galaxies, however, individual stars can’t be resolved, and so in order to figure out how far away distant galaxies are astronomers have learned to use the light from much brighter objects: Type Ia supernovae, which can flare up with a brilliance equivalent to 5 billion Suns.

Type Ia supernovae are created from a special pairing of two stars orbiting each other: one super-dense white dwarf drawing material in from a companion until a critical mass — about 40% more massive than the Sun — is reached. The overpacked white dwarf suddenly undergoes a rapid series of thermonuclear reactions, exploding in an incredibly bright outburst of material and energy… a beacon visible across the Universe.

Because the energy and luminance of Type Ia supernovae have been found to be so consistently alike, distance can be gauged by their apparent brightness as seen from Earth. The dimmer one is when observed, the farther away its galaxy is. Based on this seemingly universal similarity it’s been thought that these supernovae must be created under very similar situations… especially since none have been directly observed — until now.

An international team of astronomers working on the Palomar Transient Factory collaborative survey have observed for the first time a Type Ia supernova-creating star pair — called a progenitor system — located in the constellation Lynx. Named PTF 11kx, the system, estimated to be some 600 million light-years away, contains a white dwarf and a red giant star, a coupling that has not been seen in previous (although indirect) observations.

“It’s a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars,” says Andy Howell, a staff scientist at the Las Cumbres Observatory Global Telescope Network (LCOGT) and a co-author on the paper, published in the August 24 issue of Science. “How could these events look so similar, if they had different origins?”

The initial observations of PTF 11kx were made possible by a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at California’s Palomar Observatory as well as a high-speed data pipeline provided by the NSF, NASA and Department of Energy. The supernova was identified on January 16, 2011 and supported by subsequent spectrography data from Lick Observatory, followed up by immediate “emergency” observations with the Keck Telescope in Hawaii.

“We basically called up a fellow UC observer and interrupted their observations in order to get time critical spectra,” said Peter Nugent, a senior scientist at the Lawrence Berkeley National Laboratory and a co-author on the paper.

The Keck observations showed the PTF 11kx post-supernova system to contain slow-moving clouds of gas and dust that couldn’t have come from the recent supernova event. Instead, the clouds — which registered high in calcium in the Lick spectrographic data — must have come from a previous nova event in which the white dwarf briefly ignited and blew off an outer layer of its atmosphere. This expanding cloud was then seen to be slowing down, likely due to the stellar wind from a companion red giant.

(What’s the difference between a nova and a supernova? Read NASA’s STEREO Spots a New Nova)

Eventually the decelerating nova cloud was impacted by the rapidly-moving outburst from the supernova, evidenced by a sudden burst in the calcium signal which had gradually diminished in the two months since the January event. This calcium burst was, in effect, the supernova hitting the nova and causing it to “light up”.

The observations of PTF 11kx show that Type Ia supernova can occur in progenitor systems where the white dwarf has undergone nova eruptions, possibly repeatedly — a scenario that many astronomers had previously thought couldn’t happen. This could even mean that PTF 11kx is an entirely new species of Type Ia supernova, and while previously unseen and rare, not unique.

Which means our cosmic “standard candles” may need to get their wicks trimmed.

“We know that Type 1a supernovae vary slightly from galaxy to galaxy, and we’ve been calibrating for that, but this PTF 11kx observation is providing the first explanation of why this happens,” Nugent said. “This discovery gives us an opportunity to refine and improve the accuracy of our cosmic measurements.”

Source: Berkeley Lab news center

Inset images: PTF 11kx observation (BJ Fulton, Las Cumbres Observatory Global Telescope Network) / The 48-inch Samuel Oschin Telescope dome at Palomar Observatory. Video: Romano Corradi and the Instituto de Astrofísica de Canarias

June 30, 2012April 26, 2016 by Jason Major

Pulsar Sets New Speed Record

A pulsar may have been spotted racing through space at over 6 million miles per hour (9.65 million km/h), setting a new speed record for these curious cosmic objects. If observations are what they appear to be, astronomers will have to recalculate the incredible forces created by supernova explosions.

Seen in observations made with 3 different telescopes — NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and the Parkes radio telescope in Australia — the x-ray-emitting object IGR J11014-6103 appears to be racing away from the remnants of a supernova in the constellation Carina, 30,000 light-years from Earth.

The comet-shaped object is thought to be a pulsar, the rapidly-spinning, superdense remains of a star. The facts that it’s dim in optical and infrared wavelengths and hasn’t changed in x-ray brightness between XMM-Newton observations in 2003 and Chandra measurements in 2011 support the claim.

IGR J11014’s comet-like shape may be the result of its breakneck speed through space as its pulsar wind nebula gets blown back by the high-energy bow shock created at the forefront of its passage.

Pulsar wind nebulae are the results of charged particles streaming out from the pulsar itself. The particles, traveling at nearly light-speed, are rapidly decelerated by the interstellar medium and create a visible shock wave. In the case of IGR J11014, the pulsar wind is formed into a “tail” by its bow shock — effectively a sonic boom in front of it.

Further observations will be needed to confirm that IGR J11014 is indeed a pulsar, especially considering that actual pulsations have not yet been detected. If it is a pulsar, and is really traveling at the record-breaking speeds it appears to be — between 5.4 and 6.5 million miles per hour, more than 12 times faster than the Sun travels around the center of the galaxy — a new model of supernova explosions may be required.

Read more on the Chandra news release here.

Image: X-ray: NASA/CXC/UC Berkeley/J.Tomsick et al & ESA/XMM-Newton, Optical: DSS; IR: 2MASS/UMass/IPAC-Caltech/NASA/NSF. Video: NASA/CXC/A. Hobart.

June 22, 2012December 23, 2015 by Nancy Atkinson

Astrophoto: Supernova PTF11kly During and After

It was literally an event of stellar proportions! In August 2011, a new Type Ia supernova was seen in spiral galaxy M101 a.k.a the Pinwheel Galaxy, located 25 million light-years away. Called PTF11kly, the bright supernova was a target for many astrophotographers. But what does it look like now? Here is a side-by-side comparison by Bill Schlosser from Ohio. It shows his image of the supernova on Sept. 26th, 2011 and then more recently, on June 9th, 2012. “The first was taken through my Astro Tech 10″ RC (I have since sold it) and the second through my TEC 140mm APO,” Bill wrote, and it clearly shows the supernova at its height (brightest object in the left picture, in the lower left side of the galaxy) to what it is today — a small blue blob in the right-hand image. Bill is wondering if it is possibly a becoming nebula now?

Great comparison shots! Check out Bill’s Flickr page for more great photos.

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