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Author Topic: Hubble spots an unidentified object.  (Read 1564 times)

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Online VekseidTopic starter

Hubble spots an unidentified object.
« on: September 15, 2008, 08:47:46 PM »
The Arxiv paper is here.

Sky and Telescope has an article in more English terms. There's also a comment speculating on the nature of one of the spectral lines.

This is rather much awesomesauce. A flat out guess would be that it's a new type of supernova, but the symmetric light curve makes that rather odd - what happens in a supernova is that a whole bunch of radioactive material gets produced in an extremely short span, and we see the after glow as various heavy elements (sometimes multiple solar masses worth) decay over a more extended period.

If it is a new type of supernova, it would be telling if we could figure out what sort of star created it. Something that comes to mind is the formation of a population III star going straight from solar nebula into core collapse, with no lifespan in between - it would take a lot of time to build up heavy elements, never really living life as a star, per se.

But that's just a random guess. I know there are a lot of dumb ideas being floated around about it : )

Offline Trieste

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Re: Hubble spots an unidentified object.
« Reply #1 on: September 15, 2008, 09:03:20 PM »
If I'm reading this correctly, they hypothesize that this happened over 8 billion years ago... talk about a blast from the past. I love that aspect of cosmology ... I think it's way awesome.

Offline Revolverman

Re: Hubble spots an unidentified object.
« Reply #2 on: September 15, 2008, 09:06:28 PM »
If I'm reading this correctly, they hypothesize that this happened over 8 billion years ago... talk about a blast from the past. I love that aspect of cosmology ... I think it's way awesome.


100% agreement, its almost like a time machine.

Online VekseidTopic starter

Re: Hubble spots an unidentified object.
« Reply #3 on: September 15, 2008, 09:14:41 PM »
If I'm reading this correctly, they hypothesize that this happened over 8 billion years ago... talk about a blast from the past. I love that aspect of cosmology ... I think it's way awesome.

That's a very rough guess, because that's where the cluster it was found in is located. No parallax was detected, putting a lower limit at 130 light-years, and no significant hydrogen absorption, putting the upper limit at 11 billion yeas ago.

Note that the 8.2 billion light year bit is light travel time - when it occurred, it was about 5.5 billion light years away, and it's now a bit over 11 billion light years away, assuming that that is the rough date.

Offline Trieste

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Re: Hubble spots an unidentified object.
« Reply #4 on: September 15, 2008, 09:28:42 PM »
Am I the only one who doesn't quite grok parallax? :( Hydrogen absorption is also a bit shaky, despite my background in chem.

Also, I thought that if something was, say, 100 million light years away, it's also thought to have occurred in the past. Probably not 100 years on the nose - I think it involves some sort of physics/quantum equation - but if it's reaching us from that far away (let alone billions), it occurred in the been-and-gone as opposed to the here-and-now?

Please, Vekka-sempai, enlighten us? :)

Offline Oniya

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Re: Hubble spots an unidentified object.
« Reply #5 on: September 15, 2008, 09:49:37 PM »
Parallax isn't that hard if you start small.  Hold your finger at arm's length and point at the ceiling.  If you close one eye and then the other, the background seems to shift as far as what your finger is covering.  The closer your finger is, the bigger the shift.

The same thing happens with stars, only the 'eyes' are at opposite ends of the Earth's orbit (January and June, for example).  The closer an object is to the solar system, the more it will appear to shift compared to the other stars.

Online VekseidTopic starter

Re: Hubble spots an unidentified object.
« Reply #6 on: September 15, 2008, 10:56:46 PM »
Am I the only one who doesn't quite grok parallax? :( Hydrogen absorption is also a bit shaky, despite my background in chem.

Oniya has a good explanation of Parallax : ) Basically, with a circular orbit there isn't a point in the sky where you can't look at something from 300 million kilometers to the side.  Ideally, over the next centuries we'll have telescopes light-years apart to give us much more accurate measurements of such things.

Hydrogen absorption comes from the density of intergalactic gas more than eleven billion years ago. The Universe was a lot smaller then, and the IGM a great deal denser, meaning that we see the spectral lines that hydrogen absorbs get absorbed more in very distant objects.

Quote
Also, I thought that if something was, say, 100 million light years away, it's also thought to have occurred in the past. Probably not 100 years on the nose - I think it involves some sort of physics/quantum equation - but if it's reaching us from that far away (let alone billions), it occurred in the been-and-gone as opposed to the here-and-now?

Up to a billion light years away, that applies close enough.

Space is currently expanding at 71 kilometers per second per megaparsec. To put that in perspective, if there were no such thing as gravity, and we were each a billion kilometers apart (roughly), we would slowly accelerate apart at a rate of about 72 meters per second per year. A billion light-years apart, and that becomes several percent of c - enough for relativistic equations to have meaning but most people wouldn't care.

Once you start getting half the Universe away, though, the expansion of space starts to have a huge effect. We see it as being 8.2 billion light-years away, but it was not that far away when the light was sent, and is much, much further away now. This is an important distinction to keep in mind when looking at the size of the Universe.

Perhaps I should do more sciencey articles >_>

Offline Heika Kinzoku

Re: Hubble spots an unidentified object.
« Reply #7 on: September 16, 2008, 12:33:10 AM »
Oniya has a good explanation of Parallax : ) Basically, with a circular orbit there isn't a point in the sky where you can't look at something from 300 million kilometers to the side.  Ideally, over the next centuries we'll have telescopes light-years apart to give us much more accurate measurements of such things.

Hydrogen absorption comes from the density of intergalactic gas more than eleven billion years ago. The Universe was a lot smaller then, and the IGM a great deal denser, meaning that we see the spectral lines that hydrogen absorbs get absorbed more in very distant objects.

Up to a billion light years away, that applies close enough.

Space is currently expanding at 71 kilometers per second per megaparsec. To put that in perspective, if there were no such thing as gravity, and we were each a billion kilometers apart (roughly), we would slowly accelerate apart at a rate of about 72 meters per second per year. A billion light-years apart, and that becomes several percent of c - enough for relativistic equations to have meaning but most people wouldn't care.

Once you start getting half the Universe away, though, the expansion of space starts to have a huge effect. We see it as being 8.2 billion light-years away, but it was not that far away when the light was sent, and is much, much further away now. This is an important distinction to keep in mind when looking at the size of the Universe.

Perhaps I should do more sciencey articles >_>

To give another metaphor here, just in case it helps ...

I think this can be described as a visual Doppler Effect. Not necessarily in terms of red shift/blue shift, but in terms of emitting a sensory phenomenon whilst moving. We're having trouble nailing where exactly it was when it went supernova just because it was moving when it did it.  It's like it occurred, then moved further away before we were able to sense it. As an analogy, think that I am standing across the room from you and shout, but then before my voice reaches you, I duck out of the room. It makes it very difficult to see where the source is coming from.

... I hope that helps ... [grins]

Online VekseidTopic starter

Re: Hubble spots an unidentified object.
« Reply #8 on: September 16, 2008, 02:26:02 AM »
To give another metaphor here, just in case it helps ...

I think this can be described as a visual Doppler Effect. Not necessarily in terms of red shift/blue shift, but in terms of emitting a sensory phenomenon whilst moving. We're having trouble nailing where exactly it was when it went supernova just because it was moving when it did it.  It's like it occurred, then moved further away before we were able to sense it. As an analogy, think that I am standing across the room from you and shout, but then before my voice reaches you, I duck out of the room. It makes it very difficult to see where the source is coming from.

... I hope that helps ... [grins]

...what?

Not it at all.

We know the exact direction - enough that there is no measureable parallax. We have no reference for it. It's like trying to measure the distance to the sun when you're not allowed to use anything but your own two eyes, except it hurts less.

Offline Caeli

Re: Hubble spots an unidentified object.
« Reply #9 on: September 16, 2008, 02:28:24 AM »
What a cool article. I've always loved reading cosmology and space-related articles for this reason, even though sometimes the terminology goes a bit over my head.

Veks... you're my god. :D

Offline Trieste

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Re: Hubble spots an unidentified object.
« Reply #10 on: September 16, 2008, 02:11:13 PM »
Thank you, Oniya.

The hydrogen absorption is a bit more shaky ...

So from Oniya's explanation, having almost no parallax means that the thing is very, very far away ... but one thing that Vekseid said confused me.

We know the exact direction - enough that there is no measureable parallax.

Is the fact that it has no parallax significant because it gives us distance? Or because we know precisely where it is, and thus - using Oniya's analogy - we're not looking at it from one eye and then the other, but instead viewing it from the equivalent of a third eye in the traditional chakric place - the middle of the forehead?

Offline Oniya

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Re: Hubble spots an unidentified object.
« Reply #11 on: September 16, 2008, 02:26:35 PM »
Parallax only gives us the distance when the two viewing directions intersect somewhere.  In this case, the two viewing directions are virtually parallel, which does give us an exact direction. 

Offline Trieste

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Re: Hubble spots an unidentified object.
« Reply #12 on: September 16, 2008, 02:34:56 PM »
Direction but not distance?

Offline Oniya

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Re: Hubble spots an unidentified object.
« Reply #13 on: September 16, 2008, 02:54:01 PM »
Basically, you're making a triangle.  As the triangle gets taller (object gets farther), the two sides make a bigger angle with the base.  At a certain point, the angles get too close to 90 for us to tell the difference.  At that point, we can't tell the distance any more (two perpendicular lines won't intersect).  The direction is going to be right down the middle, though.

Offline Trieste

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Re: Hubble spots an unidentified object.
« Reply #14 on: September 16, 2008, 03:35:09 PM »
!

I grok.

I'm taking you to my calc and physics classes with me next fall. Yes, I am.

Offline The Overlord

Re: Hubble spots an unidentified object.
« Reply #15 on: September 21, 2008, 01:59:27 AM »


If it is a new type of supernova, it would be telling if we could figure out what sort of star created it. Something that comes to mind is the formation of a population III star going straight from solar nebula into core collapse, with no lifespan in between - it would take a lot of time to build up heavy elements, never really living life as a star, per se.


That is a really interesting concept, and I have to say it would be amazing to learn this can happen.

Thing is, with all that accumulated fuel to burn from the parent nebula you'd need something massive in every sense to override the outward pressure from the thermonuclear reaction, and I tend to wonder if a plethora of heavy elements would suffice, or should astronomers not be seeing prior evidence of this?

Consider a primordial binary system where the stars collided and merged in the first million years, and pushed the mass over the edge...that seems very plausible. Current models of planetary formation postulate that the 'hot Jupiters' can migrate inward from orbital drag by residue in the system, and that early gravitational forces can move planets, eject them from the system, or plunge them into the star.

Known situations such as Uranus' severe axis tilt, or the case of a massive moon like Triton orbiting so closely and in retrograde fashion proves our own system suffered some early havoc before it settled down. Having a binary collide and explode before the system gets a chance to age sounds quite possible.

Online VekseidTopic starter

Re: Hubble spots an unidentified object.
« Reply #16 on: September 21, 2008, 03:49:12 AM »
On the contrary, it's heavy elements that limit the size of stars. Fewer metals mean fewer wavelengths get absorbed while the star enters its protostar phase, allowing more mass to collapse onto the star. At extreme masses, the CNO cycle can kick in with heavy elements even before the star is fully formed, blowing material away or, apparently according to some models, blowup up as the star is forming.

Offline The Overlord

Re: Hubble spots an unidentified object.
« Reply #17 on: September 21, 2008, 07:45:39 PM »

It would be interesting to find out for sure.

On a related note-


http://news.yahoo.com/s/nm/planets_collision_dc


Offline Porphyre

Re: Hubble spots an unidentified object.
« Reply #18 on: September 22, 2008, 09:55:46 AM »
Someone sneezed on the lens. Calling it now.

Offline The Overlord

Re: Hubble spots an unidentified object.
« Reply #19 on: September 22, 2008, 05:51:35 PM »


Thing is, there are tens of thousands of known objects within the inner asteroid belt between Mars and Jupiter, and it's been said if you lumped them all together you'd get a body significantly smaller than our own moon, which has a diameter one quarter of the Earth but 0.0123 Earth's mass.

Can you imagine the debris choking this system if Earth and Venus collided? That's 1.857 Earth's mass in an orbital free-for-all of millions of pieces. This star system must be incredibly exotic and dangerous.
« Last Edit: September 22, 2008, 05:53:04 PM by The Overlord »