How close does a star have to be to kill us? Can it happen?

Factual Questions
1

The thread about Armageddon got me thinking about this (I would like to link but sorry, I forgot to copy the URL) :frowning:

If a “nearby” star can go Nova and kill us:

  1. How far does a star have to be until it doesn’t matter to us if it goes Nova or not… in other words, when does the star not become a worry? 100 Light years, 200? 300?

  2. Are there any stars close enough to us that are capable to go Nova and kill us?

  3. If so, are they old enough to make it a concern for the “near” (I know this is a very loose term in cosmic terms) future? In other words, being that even if a star went Nova we wouldn’t know until the light hit us (which would be several years) are some showing “early” signs that its main sequence is on the downward trend?

  4. Is there anything else that a star can do (or someother cosmic phenomena outside of our solar system) that can cause us harm?
    Thanks!

2

I assume you mean “supernova” (which is very different than a “nova” even though the names are similar…a nova is a sudden brightening whereas a supernova is an explosion).

(1) We’d be safe from the explosion of a star a few hundred light years away, but I’m not sure what would happen when the ejected material eventually reached us.
http://itss.raytheon.com/cafe/qadir/q2742.html

(2) Not that I know of.

(3) Betelgeuse is fairly close and is about to go supernova - but I think we’ll be ok.
http://www.astro.uiuc.edu/~kaler/sow/betelgeuse.html

(4) Colliding neutron stars or black holes (i.e., dead stars) would send high energy rays (gamma?) our way…could be strong enough to cause damage depending on how close they are. AFAIK, none of the closest ones are expected to do this any time soon.

3

The primary of alpha centauri is pretty big. If that went nova, we’d be hurting big time. :eek:

4

Sorry, I did indeed mean “supernova”.

Duh.

5

on space.com I recall a star about to go hypernova (basiaclly hteir phrase for a really big supernova) fairly close to us. They perdict that we’d be safe on the ground but it could knock out out sats and fry people in the ISS.

6

On the other hand, our own Sun can let loose a Solar Flare or Solar Prominence that could reach far enough into space to fry the Earth.

Nice day, huh? :slight_smile:

7

Some day…in the far future. Our little sun itself will grow to be a red giant and the earth will be orbiting inside it…so to speak. Something to look forward to eh?

8

Really? A flare can reach that far? I had no idea.

9

How do we know it hasn’t gone supernova yet? Maybe it has gone supernova but the light hasn’t reached us yet. :slight_smile:

10

It depends. Is the star O.J. Simpson? :smiley:

11

I was under the impression that the largest recorded flare, a couple of decades ago, dirupted some satellites, airline comm and the Canadian power grid, but that was about it.

Actually, just checking for sites, I found that we had the largest recorded flare this April. The article comments:

12

I know the electromagnetic effects can definetly effect us. When “fry” was mentioned, I was thinking the actual “flame” or “heat”.