Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

70 sextillion stars

  1. Jul 22, 2003 #1

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    http://www.cnn.com/2003/TECH/space/07/22/stars.survey/index.html

     
  2. jcsd
  3. Jul 22, 2003 #2
    I wonder who gets to name them all.
     
  4. Jul 22, 2003 #3
    How about the bad news?

    Out of all the stars in the universe, how many will go on to make Blackholes?

    Lets start with 70,000 million million million Stars, if a certain % go on to make Blackholes after going supernova, so how do we calculate the probable Blackhole count?

    Ok, lets say there are ten percent of stars that go on to make BHs.
    Then we can say that there is also one BH for every Galaxy in the Universe(presumed to be at Galactic core)someone has to estimate the Galaxy numbers.

    The we have to estimate the lifetime of a BH, the average star exists over many million years, so what is the BH age compared to the lifetime of Stars, is it equivelent, millions of years?

    A BH does not emmit radiation over millions of years, in fact it dont emit anything detectable, but lets say that a BH exists for the shortest possible moment at the end of a Stars life, the transitional moment from supernova to no-nova( moment a BH exists all light in vicinty ceases).

    Anybody know what the total Blackhole count is for our Universe? a rough figure would suffice.
     
  5. Jul 22, 2003 #4
    Also, if I blink during a supernova, can this stop a Blackhole appearing?
     
  6. Jul 22, 2003 #5

    Janus

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Way too high of a percent. Only massive stars can become black holes (3.5 solar masses and above.)

    The vast majority of stars are small and cool. (95% are smaller than our own sun.)

    If you take the region around our sun as representative, There are over 150 stars within 30 ly, and not one candidate to become a black hole among them.
     
  7. Jul 22, 2003 #6

    drag

    User Avatar
    Science Advisor

    Are we talking about the estimated amount of stars in the
    observable part of the Universe ?

    Live long and prosper.
     
  8. Jul 23, 2003 #7

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Shouldn't this be reported as the number of stars that have existed over some interval in time from our perspective...I guess 12 billion years? We don't really know how many are still out there do we? Or is this accounted for in the estimate; the number of starts that no longer exist but that can be seen?
     
  9. Jul 23, 2003 #8

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    That's right. The article says the actual number could be infinite.
     
  10. Jul 23, 2003 #9

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Why is a black hole bad news? (unless you're falling into one, of course)

    The main sequence of a star can last millions/billions of years. The time it takes for a black hole to die (evaporate) depends on its size...but it's an incredibly long time....
    http://itss.raytheon.com/cafe/qadir/q1025.html

    [?]
    Why would a black hole (from a stellar remnant) only exist for an instant?
    What do you mean by "no-nova"?

    Very large stars go supernova...that ejects lots of matter to space and then what's left of the core collapses into a black hole which then persists for what might as well be considered forever (see link above)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: 70 sextillion stars
  1. No star (Replies: 1)

  2. Strange Stars (Replies: 6)

Loading...