Supernova 2011b Gradually Fading

An anonymous reader writes "The recent stellar explosion known as 'supernova 2011b' is gradually fading after outshining its host galaxy for over a month. The explosion first flared up in early January, and peaked at magnitude 12.9, putting it within the reach of many amateur telescopes. The host galaxy, NGC 2655, lies 64 million light years away, meaning that the star exploded while the dinosaurs still roamed the planet. My own sketches are available at gkastro.tk/."

Comments

Sketches?

[TiggertheMad]

Pics or it didn't explode....

Here's my sketch

[NEDHead]

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Dinosaurs?

[name_already_taken]

I thought the dinosaurs died out 65 million years ago?

That means they were already dead for a million years, 64 million years ago.

Re:Dinosaurs?

[Suki I]

We will know the real distance when the bang gets here, as long as someone remembered to count when they saw the bang.

Re:Dinosaurs?

[wierd_w]

Sorry AC, Light cone is the correct terminology when discussing relativistic phenomena. It has to do with how the posibility function looks when graphed; it creates a cone shaped region. anything inside the cone is observable at some point in the lifetime of that photon generating event, anything outside that cone is not observable.

The point that the GP was trying to drive home is that relativity outright rejects the notion of "standardized time", and also any notion of a "universal reference point" from which to observe without also suffering from relativistic effects.

This is because time is a variable under relativity, and because all objects are in motion, and thus subject to relativistic effects. Your suggested correction of "light sphere" may not look very spherical from a specific vantage point, due to non-uniform spacial curvatures interacting with that light.

Long story short, your correction is in fact, incorrect. Sorry.

Slasdot slow as usual

[$0.02]

A supernova explodes. Slashdot reports 64 million years later.

Re:Slasdot slow as usual

[SETIGuy]

Don't worry, Slashdot will report it again tomorrow.

Re:Damn it!

[Suki I]

http://www.novaresource.org/

rhetorical question

[shadowofwind]

When an event is X light-years away, and we're just seeing it now, people speak of the event "having happened" X years ago, on the grounds that it takes X years for light to travel that distance. But how meaningful is it to think of the faraway event as being exactly concurrent with an earthly event X years ago? Light from faraway shows events from when the universe was/is in a less advanced state, so we may try to think of that as the "past". But in a way, for us, those far away events are really "now". There isn't a previous time at which we could witness them without time travel, not even in principle. Furthermore, the thought that "the event really occurred X years ago" seems to assume a universal standard of time, independent of the location and velocity of the observer, by which far apart events can be ordered. But time is not like that is it?

Re:rhetorical question

[Daniel Dvorkin]

No, it's not; you're absolutely right. In our frame of reference, it just happened recently -- and while you could say, "yeah, but in the star's reference frame, it happened tens of millions of years ago," it's also true that in the star's reference frame, dinosaurs on Earth are just now going extinct. IOW, it's not a very meaningful reference frame from where we're sitting.

The "well, actually it happened X million years ago" comments that seem to accompany every /. story about some distant, recently observed astronomical event are an example of the classic nerd failing of assuming that because we're smart people who know a lot about a lot of things, we're geniuses who know everything about everything. And I'm probably as guilty of it as anyone else ...

Re:rhetorical question

[Anonymous Coward]

In our frame of reference, it just happened recently

That's not correct. Or at least that's not how simultaneity and past/present/future are defined in relativity, which seems to be what you're referring to with "frame of reference". I suppose you could define 'now' in that way... but that's not how it's defined in modern physics.

In our inertial reference frame, it happened ~64 million years ago. In the star's reference frame, it also happened ~64 million years ago. It's true there is no such thing as a universal reference frame, so one can certainly construct inertial reference frames (e.g. with large velocities relative to us) where the event occurred at different times. Even 'now' (in that reference frame). But the velocity difference between us and the supernova is modest (in the grand scheme of the universe) and thus our two references frames roughly agree about simultaneity and so on.

It's a strange misconception that people interpret relativity to mean that all space-time events on our past light-cone are 'now'. Relativity doesn't say that. It includes a well-defined concept about what is in the past, what is in the future, and the boundary between them being 'now'. We are not immediately aware of all space-time events on the 'now' plane... because it takes time for their signals to reach us. But when we receiving signals we are able to reconstruct and deduce what happened at previous moments. It is true that inertial reference frames do not agree on what 'now' means, and thus don't agree on simultaneity. But within a particular inertial reference frame, there is a meaningful concept of 'now'.

Again, I suppose you could define 'now' in such a way, but it's not at all useful to think of the big bang happening 'right now' as we look far out into space. It makes much more sense to think in terms of it having happened 13.7 billion years ago, and we're only now receiving signals from the afterglow of the big bang from distant regions of space.

Re:Damn it!

[jc42]

If only I would of found out about the supernova back in January! Never seen one before and it is possible that there won't be another within my lifetime.

Don't worry. If you accept supernovas like this one, that's in a different galaxy than ours, there are plenty of them somewhere in the universe every year. It's only if you want one in our galaxy that you have to wait, since the frequency is on the order of one per century.

There was one in the Large Magellanic Cloud back in 1987, easily visible to the naked eye (if you were in the southern hemisphere).

Actually, it's getting to be time we had one in our galaxy. But unfortunately, they don't seem to be scheduled anywhere that we can easily read. The schedule has probably been on file at our local planning department in Alpha Centauri for 50 of our years, but we can't be bothered to make the short trip to check it out. So we'll just have to keep looking up at the night sky until something new appears there.

That's an old sketch. Here it is today.

[Anonymous Coward]

.

Sketches?

[ddd0004]

Can't you just get the software they use on CSI Miami and click "enhance" like a million times.

Re:Wow Many amateur telescopes

[Kentari]

Photographically it is well within reach of DSLRs equiped with a 200mm lens. I managed to go down to magnitude 17 (or 100 times less bright) and even fainter with a Canon 20D and a 200mm f/2.8 lens, placed on a tracking mount and exposed for about 2 hours (accumulated in exposures of a few minutes). I'm sure it would even lie within the limits of a 50mm lens. The problem becomes distinguishing it from the host galaxy.

Visually it was within reach of 4.5" beginner scopes at dark locations! These will set you back less than $200 nowadays. A $1000 12" would have produced very decent views of the SN together with it's host galaxy. There are a lot of telescopes of this size around. You obviously should take the time to visit a public observatory once.