4 ms·

Very cool, but can't help to wonder.. What is the likelihood of taking a random picture that captures the start of a supernova? How often does one happen in a g

• pavel_lishin 9y ago
  Apparently they happen about 3 times a century in the Milky Way. That's not very often, but we can see a lot of galaxies... https://en.wikipedia.org/wiki/Supernova#Discovery https://en.wikipedia.org/wiki/Supernova#Discovery
  • cabaalis 9y ago
    Did the MW all form around the same time? What I'm getting at is: will the rate of supernova increase as the stars which make up the Galaxy reach end-of-life at approximately the same rate? Will it fizzle like pop rocks at the end?
    • pvg 9y ago
      The lifespans of stars vary by orders of magnitude. The sun is about 4.5 billion years old and is not massive enough to ever be a supernova. Betelgeuse, a candidate to go supernova 'soon' is only about 10 million years old.
    • antognini 9y ago
      Galaxies can undergo bursts of star formation which are accompanied by lots of supernovae, because supernovae come from massive stars which don't live for very long. The universe was most active in star formation and supernovae about 10 billion years ago.
    • zaarn 9y ago
      The longest lived stars, red dwards, will most likely simply fizzle out like a hot plate you turned off. It is unlikely we will ever observe such an event. Even our Sun doesn't go Supernova, it just blows up a bit and discards it's outer layers, forming a white dwarf. The stars that go Supernova are much more massive (around 3 times, IIRC) and have orders of magnitude shorter lifetimes (measured in only a few hundred million years at best).
• jjaredsimpson 9y ago
  I've seen rates of supernova for the milky way as 1 per century. So that's 1 per 10^13 star-years. With 10^22 stars in the observable universe distributed uniformly we would expect something like 10^9 stars to supernova this year. But we have to consider the speed of light. So what we are really asking is something like what is the probability that light will arrive at Earth in some interval from a supernova. I'd imagine this is some integral over spherical shells receding into the distant past where there is some function defined on the shell which tracks stellar density as well as supernova probability. Beyond my expertise to even attempt napkin math.
  • vkou 9y ago
    > But we have to consider the speed of light. So what we are really asking is something like what is the probability that light will arrive at Earth in some interval from a supernova. We really don't. (We've already largely accounted for it, by only counting the stars in the observable universe.) So yes, stars supernova at a rate of ~30/second, from our current frame of reference. However, many of them are occluded by dust, or are too faint to differentiate from their neighbours/parent galaxies, or are too red-shifted away...
• yborg 9y ago
  From the Nature paper: "We note that the chance probability of this discovery is of the order of 10^−6 assuming a duration of 1 h and one supernova per century per galaxy. If we consider other factors, such as the sky conditions of the observing site and the location of the supernova away from bright host-galaxy regions, then this probability decreases by one order of magnitude."
  • T-hawk 9y ago
    Remember the principle of multiple endpoints. We only noticed this one example because it hit; we never notice all the cases that don't. If between 10^6 and 10^7 cameras have been tried out by taking pictures of space, then this one supernova incident is right at about the expected value.
    • gmiller123456 9y ago
      This would only be true if people pointed at random galaxies in the sky. There are only a few thousand galaxies in the NCG catalog that an amateur would even be able to see, and only a few dozen that an amateur would actually be interested in photographing.
  • chrisweekly 9y ago
    Duration of 1h?? That's... astonishing.