Breaking news: Supernova explodes in M95!

[JamesSavik]

Watching a star explode

 

By Daniel Stolte 23 March 2012 Source Link:==> http://www.physorg.c...12-03-star.html

 

Adam Block's image of supernova SN 2012aw (arrow) lighting up in spiral galaxy M95 was selected as NASA's Astronomy Picture of the Day. The bar-like structure giving this type of galaxy its name can be seen in the galaxy's center. (Photo: Adam Block/Mt. Lemmon SkyCenter)

 

NASA's Astronomy Picture of the Day for March 22 features a snapshot of a supernova - a massive star explosion - discovered only a week ago.

 

Using the remotely controlled Schulman Telescope at the University of Arizona's Mt. Lemmon SkyCenter, Adam Block shot this image of galaxy M95.

 

What appears to be an extra-bright star in one of its spiral arms actually is the light flash of a supernova. In this case, M95's latest supernova, SN 2012aw, was discovered on March 16 and now is identified as the explosion of a massive star.

 

"When I learned about the discovery of this supernova, I decided I could do without sleep for a night and try and take a good picture of this cosmic catastrophe," said Block, an astrophotographer. Collecting the light with the telescope took about three hours, followed by another three hours to assemble the final image.

 

The Schulman Telescope is large enough to clearly see both the galaxy and the supernova, which looks like a bright star, Block said.

 

Massive stars are the universe's hot, fast and furious: Ranging in mass from eight times to about 300 times the mass of our sun, they burn brighter than other stars, use up their fuel faster and go out with a bang of truly cosmic proportions.

 

"When you see the galaxy, you are looking at the combined glow of hundreds of billions of stars that are in that galaxy," Block said. "The fact that supernova rivals the brightness of the entire galaxy tells you something about how much energy is released."

 

Massive stars are rare, and astronomers must look many thousands of light years away from the Earth to discover one. Because they are difficult to see the further away they are, astronomers have yet to discover massive stars outside our own galaxy, the Milky Way.

 

Galaxy M95, in which supernova SN 2012aw went off, is about 38 million light years distant and spans about 75,000 light years across. M95 is a so-called barred spiral galaxy because of the bar-like feature in its center.

 

Apart from the latest supernova, galaxy M95 is special in that it helped astronomers figure out the shape of our Milky Way, Block said: "Trying to determine the shape of our own galaxy is tricky because we're in it. It's like trying to figure out the shape of your house while you're sitting in the living room."

 

Through various observations and measurements, astronomers were able to determine that the Milky Way, too, features a bar structure in its center and is roughly the same size as M95.

 

He added that right now, galaxy M95 is located in the approximate direction of Mars, in the constellation of Leo. While not visible with the naked eye, galaxy and supernova make for a good target for small telescopes.

 

"Depending on the nature of the explosion and the kind of star that blew up, we should be able to see the supernova for another couple of weeks or so," Block said. "At Mt. Lemmon SkyCenter, we want to make the universe exciting to people. What better thing to highlight than a star exploding in another galaxy?"

 

Provided by University of Arizona

 

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[hh5]

if multiple supernovas explode n black holes ... any chance affecting earth in a 2012 way?

[Rilbur]

If a star supernova'd close enough to the earth, we'd bake... but I don't think we're likely to see that.

[JamesSavik]

We're lucky that way. There aren't any stars large enough to blow close enough to hurt us.

 

This may not have been the case in the distant past. There have been numerous mass-extinctions in the planets history. Some have been accounted for and some have not.

 

There is a huge supernova remnant relatively close to earth. It's so large that it is difficult to see. It is thought to be quite old.

 

Have a look at it ==> http://apod.nasa.gov/apod/ap060519.html

[JamesSavik]

Notes-

 

SN 2012aw has tentatively been classified as a type IIp supernova.

 

A type IIp supernova is a core collapse supernova with a light curve that reaches a plateau-phase.

 

It will take some time to know for sure but so far that's what the data is saying.

 

The progenitor star has been identified as a red giant of about 8 solar masses- that's just about the minimum size for a star to become a supernova. If stars are any smaller, there is insufficient mass to cause the core to collapse. These stars slowly lose cohesion and most of their mass as they form planetary nebula. What is left becomes a white dwarf.

[hh5]

What are white holes? are there any?

they say they are the output of blackholes

is that in another dimension?

 

in a cartoon ST ... in our univ BH are birth of stars in another visa versa

[advocatus diaboli]

Wouldn't the super nova have happened billions of years ago?

[W_L]

Wouldn't the super nova have happened billions of years ago?

 

38 million light years away, so 38 million years ago, I think I was a probably a saber tooth tiger back then, without a suicidal mammoth or a weird sloth for a friend

 

Time is relative, all the dying stars we see now have been dead for a long time now, we're just reading the delayed obituaries.

[hh5]

if we were standing at its 10 millions years away ... would we be cooked?

 

38 million light years away, so 38 million years ago, I think I was a probably a saber tooth tiger back then, without a suicidal mammoth or a weird sloth for a friend

 

Time is relative, all the dying stars we see now have been dead for a long time now, we're just reading the delayed obituaries.

 

[W_L]

if we were standing at its 10 millions years away ... would we be cooked?

 

Not likely, but the shock waves influence on nearby star systems would be interesting to think about.

 

I have this idea that if a nearby star outside our solar system, say Alpha Centauri, were to go supernova, Earth and the other planets would be effected by it on some level. I think there is an equivalency in gravitational forces within galaxy and star clusters, if one star were to go nova, it would affect the corresponding interactions of other star systems.

 

Aero could probably deny my theory or support it better with advanced mathematics, (just don't steal it without giving me credit, I had thought about it after a chat with a friend, who was interested in astronomy).

[JamesSavik]

The problem with radiation is that its power fades with the square of the distance.

 

The really hot part of a supernova in the gamma and x-ray ranges drop off rather quickly.

 

The shock wave behaves like Newtons law- it isn't diminished until its acted on by another force. It eventually gets soaked up in the interstellar medium over millions of years and hundreds of light years.

[hh5]

oh well if we take that that explosion in syberia for example

it sure did knock things around

 

The influence of the force is R Squared ... perhaps a nearby star system like a light year away would be put off its general position and go into a new orbit of its own in the galaxy

 

But it would be less so at 10m LY and at 100m LY

 

That's something that we don't have control of ... gravitational forces, immense pressure, temperature, quantity of mass

we're not advance to make our own dyson sphere ... even though man has our own dyson ... that cost 300 dollars a unit

joke

 

Not likely, but the shock waves influence on nearby star systems would be interesting to think about.

 

I have this idea that if a nearby star outside our solar system, say Alpha Centauri, were to go supernova, Earth and the other planets would be effected by it on some level. I think there is an equivalency in gravitational forces within galaxy and star clusters, if one star were to go nova, it would affect the corresponding interactions of other star systems.

 

Aero could probably deny my theory or support it better with advanced mathematics, (just don't steal it without giving me credit, I had thought about it after a chat with a friend, who was interested in astronomy).

 

[hh5]

oh so it will eventually look like background radiation

 

mmm more like the ripple of a pebble being dropped

its affect dies down

 

are we sure that all that's given off gamma and x-rays .. isn't there something else?

 

The shock wave behaves like Newtons law- it isn't diminished until its acted on by another force. It eventually gets soaked up in the interstellar medium over millions of years and hundreds of light years.

 

[W_L]

Which is why Alpha Centauri would make an interesting bang? (Not to mention its a binary star system, so double your bang for double the buck ) Newton laws of motion works until space is curved and fun gets started as gravity is in play, when stars play pool on a round slanted table.

 

@hh5 There are a lot of particles/waves going off in a supernova. X-Rays and Gamma rays are just the tip of the iceberg, but since it's that far away, we're not going to get hit with killer radiation.

[JamesSavik]

When a supernova goes off, quite a lot of the energy is consumed by a huge neutrino surge. We actually detected some of them when the supernova blew in 1987.

 

Neutrinos are fairly innocuous particles. They don't usually interact with other matter. It takes a huge surge of them for us to detect them at all. They travel very fast because the neutrino surge and SN1987A light were seen within seconds of each other.

[Palantir]

As James mentioned, a star needs a mass of about eight times that of our sun before it can go supernova, so that counts out Alpha centauri..

Even the combined mass of alpha centauri A (110% solar mass) and alpha centauri B(90% solar mass) is still only a quarter of the minimum requirement for a supernova event.

[W_L]

You forgot proxima centauri, but you're right larwain. It is more of a future interest than current, they still got a lot of fuel left. However i would love to know what happens to binary systems if a star goes nova along with their neighbors interaction.

[Palantir]

I didn't really forget Proxima Centauri - just didn't bother about it since it's so small - just over one tenth of a solar mass.

Alpha Centauri A and Aplha Centauri B are what is known as main sequence stars (same as our sun), hot enough at the centre for the hydrogen present to fuse into helium, and in the normal course of events have a life of five to ten billion years.

When the hydrogen is all changed to helium a new phase starts - the core contracts but an outer shell expands from the energy of the helium being fused into carbon. This is when the star is called a red giant.

When the helium runs out the outer core drifts away to become a nebula.

The inner core contracts further to become a white dwarf and then when it cools, at the end of it's life it's a black dwarf.

 

However W_L, and this is the bit that lends some credence to your theory about Alpha Centauri, there is a special type of supernova (called SN1a) which can occur when there is a binary star system (yep, that's Alpha C) where one of the stars has reached white dwarf stage.

Most likely is a series of novae as material from the main sequence partner is continually fed to the outer surface of the white dwarf.

Occasionally, if the accretion rate is massive, this situation resolves as a supernova. - and then BOOM!! - our earth would be cactus, as a supernova can have an effect from up to 100 light years away. (Alpha C is only 4.3 light yrs).

 

Hopefully, five or ten billion years from now mankind might have developed some means of surviving, or even controlling, this sort of cataclysm.

[JamesSavik]

The maximum stable mass limit for a white dwarf is a sum call the Chandrasekhar limit. This number is about 1.38 solar masses.

 

Alpha Centuri weighs in at 1.1 solar masses, Beta Centuri at .907 solar masses. Proxima Centauri is a distant companion weighing in at only .125 solar masses. Furthermore, Proxima is an M5.5 dwarf. It's a low luminosity red dwarf that is so faint that it can't be seen by the naked eye despite being the closest star to our planet.

 

It would take millions of years and a lot of help to get any one of those objects to its Chandrasekhar limit.

 

 

There are some ~1875 stars within 50 light years of earth. Most of them are dwarfs of type K, M and are less massive than our sun- very much like Proxima Centauri.

 

On the average, of each 1000 main sequence stars in the sun's neighborhood, there are...

1 star of spectral type B (along with O type stars which are quite rare) massive blue giants are your most likely candidate to go SN Type II (core collapse)- the most devastating kind of explosion. There are actually blue and white dwarfs of type B and O but they are weird and rare and none of them in the neighborhood. Their color is influenced more by their heat than size.

 

7 stars of spectral type A

27 stars of spectral type F

65 stars of spectral type G

126 stars of spectral type K

774 stars of spectral type M

 

These numbers come from an obscure branch of astronomy called stellar population studies. And no- not all populations are the same. We live in a very placid neighborhood without many bullies or thugs.

 

Type I supernova are all very predictable. They are used as a "standard candle" for determining distances to far away galaxies. They all blow with the same energy, spectra and light curve.

 

Type II SN vary considerably. They can be very, very energetic and bright. There are a number of sub-types and the core collapse might even be non-concentric or warped leading to strange shapes and irregular distribution of matter and shockwaves.

 

 

This picture of SN 1987A was taken ~10 years after the initial outburst. The "string of pearls" is gas that has been disturbed by the shock wave.

 

 

 

This picture was taken around ~2003. The theory is that the core of the progenitor star did no collapse symmetrically which causes weird effects as the supernova ages- like the double ring structure.

 

 

 

This is a typical light curve for a type I supernova. It peaks quickly, drops several orders of magnitude and thn does a long, slow fade.

 

 

The type II SN is much more energetic. It peaks and stays hot longer and fades slower than a type I.

 

When a type II SN explodes, it creates a hell of a lot of radioactive isotopes, exotic stuff that has very short half lifes. This material decays quickly adding to the radiation output of the event. Within this radioactive furnace, new heavy elements are being forged by r-process (rapid) and s-process (slow) nuclear decay. As the elements age, they become more and more stable and are recycled by the galaxy and used to create new stars and planets.

 

There is something very Zen about type II SN- it is creation and annihilation in the same event.

[W_L]

James, do I detect an amateur astronomer in there?

 

I've dabbled in astronomy a little, but my eyesight is far too poor to make out stars with a regular telescope without computer enhancements for recording.

 

And yes, it is zen to think about how these supernovas will eventually become stellar nurseries after they die. They will help grow new star systems and maybe even planetary systems as the debris cools and form planets. That Simba is the circle of life!