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Thread: What kind of star was the supernova in the Crab nebulae before its explosion?

  1. #1
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    What kind of star was the supernova in the Crab nebulae before its explosion?

    Centuries ago there was a famous supernova explosion in what we know now as Messier 1 also called the Crab nebula. But what type of star was it before it explodes? And was it a distant or nearby star before it has explode ,and how bright was the explosion itself? What was the visible (apparent) magnitude at the maximum of the explosion? What happens when a supernova occurs over an hour or so (at night of course) and it is clear outside and it reaches magnitude -19,00 ,what do i see changing outside when i wake up in the night?

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    Cool Crab Nebula

    Quote Originally Posted by Denis12
    Centuries ago there was a famous supernova explosion in what we know now as Messier 1 also called the Crab nebula. But what type of star was it before it explodes? And was it a distant or nearby star before it has explode ,and how bright was the explosion itself? What was the visible (apparent) magnitude at the maximum of the explosion? What happens when a supernova occurs over an hour or so (at night of course) and it is clear outside and it reaches magnitude -19,00 ,what do i see changing outside when i wake up in the night?
    Denis12
    The star was ~ 6500 ly-years away. It has a pulsar and was likely a type-2 core collapse supernova. They are typically 8-20 solar masses.O,A,B stars mostly...but not exclusively. It's magnitude was estimated at ~..-6.
    Let's say we pick on Alnitak in Orion's Belt. What you would see would depend entirely on how close you are, and with what instruments you are using. We'll let you be supernatural for a week, so you survive at unrealistically close distances in a fully instrumented ship.The initial brightening is time delayed from the collapse. The prompt neutrino burst would
    set off Cherenkov radiation in water detectors....you might even see flashes of light thru your eyes, in the aqueous humor, vitreous humor...if not the nerves themselves being stimulated. Strong gravtational waves would be palpable at close distances, distorting body parts first in one plane, then orthogonal to that...coincident with the neutrino burst.
    Asymmetries in supernovae explosions lead to pairs of incandescent torii (rings) ejected from the two poles, stretching out the ejecta cloud in the shape of a football....a prolate spheroid. The temperature spikes around 200,000,000 K, creating an ultraviolet flash...(superyou doesn't sunburn).
    The optical brightness increases for a few weeks as it is powered by radioactive decays...largely nickel isotopes...and the surface area of the fireball increases. The largest expansion velocity runs ~ 10% the speed of light.
    The pulsar formed can have a variety of transverse velocities...from ~10 km/sec...up to >2000 km/sec(though these are rare). If superyou in your spaceship were to survive the shock wave...at 30,000 km/sec...you could wait till the cooling media recombined after ~ a few months to years...and watch the pulsar race by from inside the remnant...cool! The technology to do this doesn't exist. ..but the mind trip is fun.
    Eventually, the ejecta speads throughout the local area of the explosion. The iron in your hemoglobin formed this way, as did the potassium in your nerves, the xenon in your neighbors headlights, the gold in our oceans, the mercury in your thermometer, the silver in all x-rays, and the uranium in the a-bombs and reactors. Boom. Pete.

    Check out Ian Shelton and Hector, the night watchman at Cerro Tololo on Google....they saw SN 1987a about the time it brightened ~ 165,000 ly-years away.
    Last edited by trinitree88; 2006-Apr-07 at 11:06 PM.

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    ...Alnitak in the Big Dipper...
    Minor nitpick.
    Alnitak is the eastern most star in the belt of Orion (from east to west: Alnitak, Alnilam, Mintaka).
    The stars of the Big Dipper are (from the end of the handle to the bowl); Alkaid, Mizar (and Alcor), Alioth, Megrez, Phecda (or Phad), Merak, Dubhe.

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    Smile ooops...

    Quote Originally Posted by Kaptain K
    Minor nitpick.
    Alnitak is the eastern most star in the belt of Orion (from east to west: Alnitak, Alnilam, Mintaka).
    The stars of the Big Dipper are (from the end of the handle to the bowl); Alkaid, Mizar (and Alcor), Alioth, Megrez, Phecda (or Phad), Merak, Dubhe.
    I should never post...post glass of wine...just a few slaps up side of the head...Kudos Pete.

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    Quote Originally Posted by trinitree88
    Denis12
    The star was ~ 6500 ly-years away. It has a pulsar and was likely a type-2 core collapse supernova. They are typically 8-20 solar masses.O,A,B stars mostly...but not exclusively. It's magnitude was estimated at ~..-6.
    Let's say we pick on Alnitak in the Big Dipper. What you would see would depend entirely on how close you are, and with what instruments you are using. We'll let you be supernatural for a week, so you survive at unrealistically close distances in a fully instrumented ship.The initial brightening is time delayed from the collapse. The prompt neutrino burst would
    set off Cherenkov radiation in water detectors....you might even see flashes of light thru your eyes, in the aqueous humor, vitreous humor...if not the nerves themselves being stimulated. Strong gravtational waves would be palpable at close distances, distorting body parts first in one plane, then orthogonal to that...coincident with the neutrino burst.
    Asymmetries in supernovae explosions lead to pairs of incandescent torii (rings) ejected from the two poles, stretching out the ejecta cloud in the shape of a football....a prolate spheroid. The temperature spikes around 200,000,000 K, creating an ultraviolet flash...(superyou doesn't sunburn).
    The optical brightness increases for a few weeks as it is powered by radioactive decays...largely nickel isotopes...and the surface area of the fireball increases. The largest expansion velocity runs ~ 10% the speed of light.
    The pulsar formed can have a variety of transverse velocities...from ~10 km/sec...up to >2000 km/sec(though these are rare). If superyou in your spaceship were to survive the shock wave...at 30,000 km/sec...you could wait till the cooling media recombined after ~ a few months to years...and watch the pulsar race by from inside the remnant...cool! The technology to do this doesn't exist. ..but the mind trip is fun.
    Eventually, the ejecta speads throughout the local area of the explosion. The iron in your hemoglobin formed this way, as did the potassium in your nerves, the xenon in your neighbors headlights, the gold in our oceans, the mercury in your thermometer, the silver in all x-rays, and the uranium in the a-bombs and reactors. Boom. Pete.

    Check out Ian Shelton and Hector, the night watchman at Cerro Tololo on Google....they saw SN 1987a about the time it brightened ~ 165,000 ly-years away.
    Thanks for that Trinitree, that was actually fun to read.

  6. #6
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    Quote Originally Posted by trinitree88
    If superyou in your spaceship were to survive the shock wave...at 30,000 km/sec...
    I've been curious what speed the blast might be. About what percent of a supernova's mass is traveling at that speed?
    We know time flies, we just can't see its wings.

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    Wink you're welcome...

    Quote Originally Posted by Dragon Star
    Thanks for that Trinitree, that was actually fun to read.
    Dragonstar...You're welcome. It's nice being supernatural in a sci-fi kind of way every now and then....

    George, not much mass is converted to energy in the supernova...percentage wise. A 25 solar mass star leaves ~ a one solar mass pulsar, and ~ 24 solar masses of ejecta. So 24/25 runs ~ 96 % ejecta...lots of dust for the universe. The 8 solar mass collapse leaves ~ 7 solar masses.(and the one solar mass pulsar)..so 7/8 runs ~ 87.5 %. The velocity for the ejecta runs 25,000 km/sec + or - 5,000 km/sec. (Alexei Fillipenko, SN 1987a, Ap. J.) It is entirely possible for such a cloud to make it rain for 40 days and nights. Pete.
    Last edited by trinitree88; 2006-Apr-07 at 11:09 PM.

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    Quote Originally Posted by trinitree88


    Dragonstar...You're welcome. It's nice being supernatural in a sci-fi kind of way every now and then....

    George, not much mass is converted to energy in the supernova...percentage wise. A 25 solar mass star leaves ~ a one solar mass pulsar, and ~ 24 solar masses of ejecta. So 24/25 runs ~ 96 % ejecta...lots of dust for the universe. The 8 solar mass collapse leaves ~ 7 solar masses.(and the one solar mass pulsar)..so 7/8 runs ~ 87.5 %. The velocity for the ejecta runs 25,000 km/sec + or - 5,000 km/sec. (Alexei Fillipenko, SN 1987a, Ap. J.) It is entirely possible for such a cloud to make it rain for 40 days and nights. Pete.
    Thanks. If my math is correct, a 10 solar mass sn at 10 lyrs would boost a 1 a.u. square disk knot of .1 solar mass by less than 1 millionith km/sec, if it absorbed 100% of the blast material's momentum (contrary to a prior post of mine).
    Last edited by George; 2006-Apr-10 at 02:58 PM.
    We know time flies, we just can't see its wings.

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    Wink

    Quote Originally Posted by George
    Thanks. If my math is correct, a 10 solar mass sn at 10 lyrs would boost a 1 a.u. square disk knot of .1 solar mass by less than 1 millionith km/sec, if it absorbed 100% of the blast material's momentum (contrary to a prior post of mine).
    Something is off in the math I'd say, George. I checked my pre-talk numbers with a dozen peers before opening up mouth in public. I did make an error in a collapse estimate. But, Fillipenko's ejecta comes out to ~ 45 % of the Sn energetics.

    let's see, ~ 2 times 10 53 ergs...total for a type 2 core collapse.
    solar mass ~ 2 times 1033 grams....velocity 30,000 km/sec...is 3 times 104 km/sec...or ~ 3 times 107m/sec....or 3 times 109cm/sec. Kinetic energy = 1/2 mv2....So,
    1/2 (2 times 10 to 33 grams)( 3 times 109 cm/sec)2...about 9 times 1051 ergs.

    then 9 times 1051 divided by the total 2 times 1053...comes out to ~ 4.5 % of the total energy of the explosion.per solar mass of ejecta pete .... use ergs not joules. These are the maximum numbers,,,typical ejecta are a lot slower.

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    trinitree88, did you mean to say Fillipenko's ejecta is about 4.5% (in lieu of 45%)? I thought it was closer to 1%, actually.

    Using your helpful values, 9e51 ergs is released. A 1 sq. a.u. cloud would receive from sn at 10 lyrs. 2e-9 percent of this amount, or about 1.8e43 ergs for a single, unabated solar mass ejecta.

    This should equate, assuming I am not wrong again, to about 6e-6 km/sec (0.013 mph) momentum exchange (at 100% transfer). A 10 solar mass ejecta would still only boost it to 0.13 mph.

    So, thanks, you are correct that my math was off. I would have liked to have seen a little more supernova kick, however.
    We know time flies, we just can't see its wings.

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