Notices
Results 1 to 10 of 10

Thread: Super Novae Near Earth

  1. #1 Super Novae Near Earth 
    New Member
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    3
    I am wondering if there could be a super nova close enough to Earth that it would be bright enough to see during the day without it killing us due to radiation, or many years later when the explosion reaches us? I know any star in our galaxy could theoretically go super nova, but would a star on the opposite side of the galaxy still be brighter to us than our sun, and how close would a super nova have to be to give off deadly amounts of radiation?


    What range of distances could this star be?


    Reply With Quote  
     

  2.  
     

  3. #2 Re: Super Novae Near Earth 
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Location
    Heidelberg, Germany
    Posts
    1,624
    Quote Originally Posted by Pillar
    I am wondering if there could be a super nova close enough to Earth that it would be bright enough to see during the day without it killing us due to radiation, or many years later when the explosion reaches us? I know any star in our galaxy could theoretically go super nova, but would a star on the opposite side of the galaxy still be brighter to us than our sun, and how close would a super nova have to be to give off deadly amounts of radiation?


    What range of distances could this star be?
    I do not know the exact answer, but I can tell you this: Only very high-mass stars can evolve into a supernova. Since they are also very bright, they are easy to detect. Therefore we know that the closest of these stars are at least 450 pc (parsec) away. They are also still pretty young, so there will be no supernova from there within the next few million years. I would have to look up or calculate how much such an event would be of potential harm to us, but I'd guess, it would be negligible.

    There have been very bright supernovae in our galaxy that were observed by men. There is e.g. the supernove from the 11th century that was discovered by the Chinese and others which now can be observed as the Crab nebula. It is about 2000 pc away, and it has not affected Earth in any way.


    Reply With Quote  
     

  4. #3  
    Forum Junior
    Join Date
    Jul 2008
    Location
    Australia
    Posts
    250
    G'day from the land of ozzzzzz

    This interesting reading on supernova

    http://arxiv.org/abs/0804.4350
    Physics of Supernovae: theory, observations, unresolved problems

    Authors: D. K. Nadyozhin
    (Submitted on 28 Apr 2008)

    Abstract: The main observational properties and resulting classification of supernovae (SNe) are briefly reviewed. Then we discuss the progress in modeling of two basic types of SNe - the thermonuclear and core-collapse ones, with special emphasis being placed on difficulties relating to a consistent description of thermonuclear flame propagation and the detachment of supernova envelope from the collapsing core (a nascent neutron star). The properties of the neutrino flux expected from the corecollapse SNe, and the lessons of SN1987A, exploded in the Large Magellanic Cloud, are considered as well.
    Smile and live another day
    Reply With Quote  
     

  5. #4  
    Moderator Moderator Janus's Avatar
    Join Date
    Jun 2007
    Posts
    2,205
    Yes it is possible to have such a supernova. It has already happened!

    In 1006 AD, a supernova appeared with a maximum apparent magnitude of -7.5 (about a quarter of the brightness of the full moon). It was visible in daylight for several days, and some accounts say that it actually(at night) cast a shadow.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


    Edit/Delete Message
    Reply With Quote  
     

  6. #5  
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Location
    Heidelberg, Germany
    Posts
    1,624
    It is said that the brightest SNe can be as bright as 10 billion times the sun. From this assumption one can calculate that such a SN at a distance of 450 pc (Orion nebula) would be as bright as about -12 mag (apparent magnitude). This is almost as bright as the full moon.
    Reply With Quote  
     

  7. #6  
    Suspended
    Join Date
    Jan 2008
    Posts
    439
    A star to the North of Orion, it's called (excuse my spelling..) Betelgeuse and it is a giant red. It could go off today tomorrow or upto a few hundred years ago, we won't know till the pulse reaches earth, then it will totally immediately destroy all life on one side of the planet in a mere millionth of a second, the rest of life would die within 12 hours. When one of these goes off it outshines the whole of the rest of the galaxy. May God have mercy on us all, you have been warned!

    Read it for yourself....

    http://www.sai.msu.su/apod/ap980419.html
    Reply With Quote  
     

  8. #7  
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Location
    Heidelberg, Germany
    Posts
    1,624
    Huh? Where on this page are the dangers of such an event described? I would think, it would be a spectacular firework. Not much more.

    Here is an estimate on he risks of nearby SNe I found.
    http://www.tass-survey.org/richmond/answers/snrisks.txt
    Reply With Quote  
     

  9. #8 Re: Super Novae Near Earth 
    Forum Ph.D.
    Join Date
    Dec 2006
    Posts
    959
    Quote Originally Posted by Dishmaster
    ]
    I do not know the exact answer, but I can tell you this: Only very high-mass stars can evolve into a supernova. Since they are also very bright, they are easy to detect. Therefore we know that the closest of these stars are at least 450 pc (parsec) away. They are also still pretty young, so there will be no supernova from there within the next few million years. I would have to look up or calculate how much such an event would be of potential harm to us, but I'd guess, it would be negligible.
    I thought I read somewhere that Rigel is a candidate to evolve into a supernova tomorrow, or in a few million years. Rigel is the most powerful star within 1000 light years and the best current distance estimate is around 770 light years with a 10% to 20% margin of error. This is considerably less than 450 parsecs.
    If Rigel did "go" supernova I don't think this would have far-reaching consequences, for the Earth and the Solar System, but I could be wrong.
    Probably the supernova could be seen during daytime but again I am not completely certain.
    Reply With Quote  
     

  10. #9 Re: Super Novae Near Earth 
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Location
    Heidelberg, Germany
    Posts
    1,624
    Quote Originally Posted by Halliday
    I thought I read somewhere that Rigel is a candidate to evolve into a supernova tomorrow or in a few million years.
    Rigel is indeed only 240 pc away, but with a spectral type of B8 and a stellar mass of around 17 solar masses, it is among the light-weights of the massive stars. It has already reached the supergiant phase, i.e. it is at the end of its life cycle. The final state would probably be a supernova, but rather a "mild" one.
    Reply With Quote  
     

  11. #10  
    Forum Freshman
    Join Date
    Oct 2008
    Posts
    5
    Yeah, wouldn't that be a sight. I really wish some supernova went off somewhere nearby (not too close though).
    Just imagine living with two suns for a while.

    There have to be massive stars in our galaxy that are on the verge of dying.
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •