Type 1a Supernova In Ursa Major!

This is the closest supernova since 1987a (which was actually much closer than this one, in the Magellanic Clouds), and it’s visible through modest backyard telescopes in the northern hemisphere.  I haven’t tried yet (it’s been too dang cold here) but if it isn’t cloudy tomorrow, I will try.  It’s in the Cigar Galaxy, M82, and Universe Today has a great story explaining how to find it:

Universe Today: Bright New Supernova Blows Up in Nearby M82, the Cigar Galaxy

This supernova is a Type 1a, which means it was a white dwarf star exploding after gobbling up too much matter from a giant star companion.  These explosions occur in such a specific set of circumstances that astronomers can use them as standard candles.

To tell how far away a star is, you can use parallax (see how much it seems to shift in the night sky over the course of the Earth’s orbit), but this only works for relatively nearby objects.  For things in distant galaxies, you have to get fancier.  Another trick is to see how much fainter things have gotten; the inverse square law means a light source will appear dimmer the further away you get — in fact, the intensity will be inversely proportional to the square of the distance.  If you happen to know how bright a candle actually is, then, you can calculate its distance by measuring how much dimmer it is compared to how much light you know it’s actually giving out.

But that’s the problem — if you don’t know how bright that candle is, how can you figure out its distance?  You need some sort of “standard candle”, a candle of known brilliance.  With Type 1a supernovas, astronomers got their standard candle.  Since these supernovas occur due to the infalling material from a companion star reaching a critical mass, they always happen at the same intensity — it’s dictated by that critical mass.  Therefore, studying the brilliance of a Type 1a supernova lets astronomers measure the size of the Universe.  (To a point.  Stupendously brilliant though supernovae are, they are eventually too distant to be visible.  But you can use these standard candles to calibrate other tricks for measuring the distance to things.)

So if you have a small telescope and you feel moved to look for this object, think about what you are seeing.  Not just a tremendous explosion of unimaginable intensity — but also one of the most important keys to the size of the Universe.


Leave a comment

Filed under Space

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s