New supernova detected

[Delta4Embassy]

Well, 'new' in astronomical terms as it's 12 million ly away so happened 12 million years ago.

SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids

"SUPERNOVA! Approximately 12 million years ago, a white dwarf star in the galaxy M82 exploded. This week, light from the distant supernova finally reached Earth. Amateur astronomers can see it through backyard telescopes as a fireball of magnitude +11.2 in one of the galaxy's dusty spiral arms. Leonard Ellul-Mercer photographed it from his observatory in Malta on Jan. 22nd:

Although it is 12 million light years away, M82 is considered to be a next-door neighbor of the Milky Way. Indeed, this is the nearest supernova to Earth since SN 1993J exploded 21 years ago. The relative proximity of the blast makes it an attractive target for astronomers to study. Light curves from previous supernovas of this type suggest that the fireball could continue to brighten for the next two weeks.

If you have a GOTO telescope, this evening command it to slew to the "cigar galaxy" or "M82," and watch the explosion unfold."

 

[Mr. H.]

Yeah, saw this on the internets news this morning.

 

[waltky]

Supernova may come from white dwarf...

Dead stars 'can re-ignite' and explode
28 August 2014 ~ Astronomers have shown that dead stars known as white dwarfs can re-ignite and explode as supernovas.

The discovery appears to solve a mystery surrounding the nature of a particular category of stellar explosions known as Type Ia supernovas. Theorists suspected that white dwarfs could explode due to a disruptive interaction with a companion star, but lacked definitive evidence until now. Details of the research appear in the journal Nature. The "smoking gun" in this case was the detection of radioactive nuclei being generated by nuclear fusion in the cosmic blast. Astronomers have long had the tools to detect the signature of this fusion, but had to wait for a supernova to explode nearby in order to begin their observations. Towards the end of its life, a star with the mass of the Sun will shed its outer layers as its core shrinks down to become a white dwarf. Left to their own devices, single white dwarfs will just cool off slowly over time.

This artist's impression shows a possible mechanism for a Type Ia supernova

But there is a maximum mass at which a white dwarf can remain stable - a property known as the Chandrasekhar limit, after the Indian-American astrophysicist Subrahmanyan Chandrasekhar. If a white dwarf steals matter from a stellar companion, or collides with another white dwarf, the extra weight can compress the carbon in the star's core until this element undergoes nuclear fusion. The carbon is fused into heavier elements with a sudden release of energy that tears the star apart. Although Type Ia supernovas are expected to occur frequently across the Universe, they are rare occurrences in any one galaxy, with typical rates of one every few hundred years. But an opportunity to observe one of these events came on 21 January 2014, when students at the University College London's teaching observatory at Mill Hill in the UK detected a type Ia supernova, later named SN2014J, in the nearby galaxy M82. Theorists propose that the carbon and oxygen found in a white dwarf should be fused into radioactive nickel during a supernova.

This nickel should then quickly decay into radioactive cobalt, which would itself subsequently decay, on a somewhat longer timescale, into stable iron. Type Ia supernovas that exploded long ago are the cosmic sources of the iron in the Sun, the Earth and in our blood. This decay chain generates gamma-rays that give rise to bright emission from the location of the supernova. Eugene Churazov and colleagues studied gamma-ray data gathered by the European Space Agency's Integral spacecraft between 50 and 100 days after the explosion. By this time, Dr Churazov explained, "the white dwarf has already expanded to a size larger than our solar system". He told BBC News: "The envelope of ejecta (debris) is semi-transparent, so no matter where the gamma-rays are produced, they are able to escape through the ejecta with a probability on the order of 60-70%."

Type Ia supernovas are relatively rare occurrences in any one galaxy

They looked for - and found - the signature of cobalt decay in the profile of gamma-ray emission from the supernova. Moreover, the observed amount of gamma-ray emission was also an excellent match for theoretical models of a white dwarf explosion. However, the researchers were not able to distinguish between the two theoretical scenarios for the initiation of a white dwarf supernova. Dr Churazov explained: "It is perfectly consistent with the simplest scenario, of a single white dwarf with a mass close to the Chandrasekhar limit. But we cannot exclude with this data that this event was caused by a merger [of two white dwarfs]." In a viewpoint piece in the same edition of Nature, Robert P Kirshner, from the Harvard-Smithsonian Center for Astrophysics in Massachusetts, wrote: "Upsetting the conventional wisdom is always a joy in science. You can get prizes for that." But, he explained, "there is also a deep pleasure in showing decisive evidence on an important physical idea that has been used without proof for decades," adding: "It is a wonderful result."

BBC News - Dead stars can re-ignite and explode

 

[Delta4Embassy]

The good news about supernovas is by the time you notice one, if not already dead you're okay.

 

[mudwhistle]

The good news about supernovas is by the time you notice one, if not already dead you're okay.

Tell that to the Klingons.

 

[Vikrant]

The good news about supernovas is by the time you notice one, if not already dead you're okay.

There is another good thing about supernova. Once the massive star explodes in what we call supernova. The heavy materials that were formed at its core may begin to consolidate into planets. The left over hydrogen may be enough to form a small star like our Sun. So it has potential to give birth to another system just like our solar system. It is kind of strange to imagine that life is an outcome of such a violent even in the cosmos for it is hard to imagine anything more explosive than supernova.

 

[Delta4Embassy]

There is another good thing about supernova. Once the massive star explodes in what we call supernova. The heavy materials that were formed at its core may begin to consolidate into planets. The left over hydrogen may be enough to form a small star like our Sun. So it has potential to give birth to another system just like our solar system. It is kind of strange to imagine that life is an outcome of such a violent even in the cosmos for it is hard to imagine anything more explosive than supernova.

Gamma ray bursts come readily to mind.

 

[Vikrant]

Gamma ray bursts come readily to mind.

Gamma ray burst definitely have more far-reaching damage potential but they look more like beam not explosion.

 

[waltky]

It could be the most powerful supernova ever detected...

Colossal star explosion detected
Astronomers have seen what could be the most powerful supernova ever detected. The exploding star was first observed back in June last year but is still radiating vast amounts of energy.

At its peak, the event was 200 times more powerful than a typical supernova, making it shine with 570 billion times the brightness of our Sun. Researchers think the explosion and ongoing activity have been boosted by a very dense, highly magnetised, remnant object called a magnetar. This object, created as the supernova got going, is probably no bigger than a major city, such as London, and is likely spinning at a fantastic rate - perhaps a thousand times a second. But it probably also is slowing, and as it does so, it is dumping that rotational energy into the expanding shroud of gas and dust thrown off in the explosion.

Before and after: This event was more than twice as luminous as the previous record-holding supernova​

Prof Christopher Kochanek, from Ohio State University, US, is a member of discovery team. This is how he explains the process of supercharging a supernova: "The idea is that this thing at the centre is very compact. It's probably about the mass of our Sun, and the garbage into which it is dumping its energy is about five to six times the mass of our Sun, and expanding outwards at a rate of, let's say, 10,000km/s. "The trick in getting the supernova to last a long time is to keep dumping energy into this expanding garbage for as long as you can. That's how you get maximum bang for your buck," he told this week's Science In Action programme on the BBC World Service. Details of the event are reported in the latest edition of the journal Science.

The super-luminous supernova, as it is termed, was spotted some 3.8 billion light-years from Earth by the All Sky Automated Survey for SuperNovae (ASAS-SN). This uses a suite of Nikon long lenses in Cerro Tololo, Chile, to sweep the sky for sudden brightenings. Follow-up observations with larger facilities are then used to investigate targets in more detail. The intention of ASAS-SN is to get better statistics on the different types of supernovas and where they are occurring in the cosmos. Astronomers have long been fascinated by these monster explosions and have come to recognise just how important they are to the story of how the Universe has evolved. Not only do they forge the heavier chemical elements in nature but their shockwaves disturb the space environment, stirring up the gas and dust from which the next generation of stars are formed. The source star for this reported supernova must have been colossal - maybe 50 to 100 times the mass of our Sun.

Artist's impression: Imagine standing on a planet 10,000 light-years from the supernova​

Such stars begin very voluminous but then shed a lot of mass in great winds that blow out into space. So, by the time this star ended its life, it was very probably greatly reduced in size. "It would have been quite small at the time of death, not tremendously bigger than the Earth," said Prof Kockanek. "It would have been very hot, however: about 100,000 degrees at the surface. Basically, it would have got rid of all of its hydrogen and helium, leaving just the material that had been burnt into carbon and oxygen." There are signs that the supernova may be about to fade, and the team have time on the Hubble space telescope in the coming weeks to try to further understand the mechanisms driving the supernova. "It is an explosion and eventually all explosions have to fade," Prof Kockanek told the BBC. "If it never fades then our interpretation of the event would have to be wrong. On the other hand, if this interpretation is wrong then it's an even more unique object and so in some sense one would be perfectly happy living with that alternative."

Colossal star explosion detected - BBC News

 

[waltky]

Exploding stars left mark on Earth...

Exploding stars left recent, radioactive mark on Earth
Wed, 06 Apr 2016 - Two studies confirm that multiple supernovae have showered the Earth with radiation within the last few million years.

One study reports traces of radioactive iron-60, a strong indicator of supernova debris, found buried in the sea floor right across the globe. A second paper models which specific supernovae are most likely to have splattered this isotope across our historic, galactic neighbourhood. Both appear in the journal Nature. The periods of bombardment highlighted by the two teams do not coincide with any mass extinction events - and indeed, the predicted locations of the culprit supernovae are not quite close enough to unleash that level of destruction. But the blasts may nonetheless have affected the Earth's climate and thus, the evolution of life.

Importantly, the two sets of results are entirely consistent, according to Dieter Breitschwerdt from the Berlin Institute of Technology, Germany, who led the modelling research. His team has spent years studying the "local bubble": a ballooning region of hot gas, 600 light-years across, that surrounds the Solar System and dominates our stellar neighbourhood. It was formed, Prof Breitschwerdt and his colleagues have found, by upwards of a dozen supernovae all blowing up within a nearby, moving clump of stars. Their new paper pinpoints those explosions. "We now can make a table of the stars - what mass they had, when they exploded, and where they were," he told the BBC News website.

Specifically, his team calculated how much iron-60 those supernovae would have sprayed into space - and how much the Earth could have swept up, based on the Solar System's path as it orbits around the Milky Way. The tiny quantities of this isotope found in the Earth's crust - first detected in samples from the bottom of the Pacific Ocean in 1999 - show a peak at about two million years ago. So, do the closest explosions in Prof Breitschwerdt's table match that peak? The short answer is yes. The nearest blast in the simulation took place 2.3 million years ago, and the second-nearest 1.5 million years ago.

That is quite a spread - but a prolonged, recent scattering of iron-60 is precisely what the other Nature paper reports, based on atom-counting measurements from 120 sea-bed samples spanning the Indian, Pacific and Atlantic Oceans. Together, these new samples cover 11 million years of Earth's geological history - and they reveal an increased smattering of iron-60 between 1.5 and 3.2 million years ago. "We were very surprised that there was debris clearly spread across 1.5 million years," said that study's lead author Anton Wallner, a nuclear physicist at the Australian National University in Canberra. "It suggests there were a series of supernovae, one after another."

Coincidental cooling?