Comments on: More M95 supernova news: progenitor found!

By: Matt B.

Matt B. — Fri, 25 May 2012 04:31:24 +0000

@9 Janine: You can get a quick order of magnitude estimate using this rule of thumb: light travels about one million times as fast as sound in normal conditions. In fact, the speed of light is close to one billion feet per second, and the speed of sound is close to one thousand feet per second. (In other situations, a good way to think of the speed of sound is that it’s about 1/5 of a mile per second.)

So 38 million light-years would take ~38 trillion years! Almost 3,000 times the age of the universe.

Please forgive the lateness of my reply.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 31 Mar 2012 05:56:30 +0000

@ ^ Nigel Depledge : Definitely!

As for the BA’s books, I can’t wait till he writes a third one and then more … 8)

(Yes, BA, that’s a hint in case you read this. Pretty please with galaxies on top? )

By: Nigel Depledge

Nigel Depledge — Wed, 28 Mar 2012 14:41:00 +0000

@ MTU (24) -
What we need is a very very large radio telescope on the far side of the moon.

By: Nigel Depledge

Nigel Depledge — Wed, 28 Mar 2012 14:38:03 +0000

MTU (18) said:

As others have pointed out and the BA has discussed in his second book

He wrote a second book?

By: lepton

lepton — Mon, 26 Mar 2012 10:48:37 +0000

@CB

“a recession velocity of 800km/s which is over 2x the speed of sound at STP.”

You mean 800m/s?

By: Messier Tidy Upper

Messier Tidy Upper — Sun, 25 Mar 2012 12:00:46 +0000

@ ^ Mr D : Oh well, pity. Maybe one day in the distant future with much improved technology? Thanks I guess for that & #22 too.

By: Mr. D

Mr. D — Sun, 25 Mar 2012 01:41:02 +0000

@17:
“Anyone know if they can detect the pulsar that may have formed from SN 2012aw and, if so, how soon until it is expected to be observable?”

Never. We’re barely detecting pulsars in the Magellanic Clouds and contemplating finding pulsars in Andromeda and the Triangulum galaxy with future radio telescopes. Pulsars so far away as M95 are right off the table.

By: Mr. D

Mr. D — Sun, 25 Mar 2012 00:55:31 +0000

” It’s probable the star had more mass when it was younger, and shed a lot of it during its short, furious life.”

Actually no. An 8 solar mass, solar metallicity, zero age main sequence star will not lose any significant amount of mass before going supernova. It’s above 20 solar masses that mass loss really kicks in with a vengeance. So unless M95 is really very enriched, the progenitor of SN2012aw pretty much had the mass it always had.

(see Figure 16 of Woosley, Weaver & Heger, 2002, RevModPhys, 74, 4, 1015)

By: Janine

Janine — Sat, 24 Mar 2012 20:17:34 +0000

@CB The naive answer was the one I was looking for. And I’m glad I got the equation right- maths is not my forte. Thanks! (I’m guessing that that’s ‘never’ either way.)

Wow, I had no idea about taking into consideration the effects of the expansion of the universe. But if that’s the case, what about the direction the galaxy is moving in, in relation to our own? The local effects of other galaxies’ gravity on their and our trajectory surely mean it’s more complex than merely that we’re moving away from them at universe expansion rate? (also, this just got even cooler! Aaand, I really need to learn how to use Wolfram Alpha. …effectively, I mean.)

By: Richard Drumm The Astronomy Bum

Richard Drumm The Astronomy Bum — Sat, 24 Mar 2012 11:54:58 +0000

Too bad we don’t have actual spectra from the progenitor…
I wonder if a telescope could be fitted with an objective prism the way te 10″ astrograph at Fan Mountain Observatory was in its heyday. If not an objective prism, then maybe one in the light path somewhere. Better to have a messy spectra that way than none at all.