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View Full Version : The Strange Nebula Around Eta Carinae



Fraser
2006-Apr-14, 04:52 AM
SUMMARY: Eta Carinae is an unusual variable star just 8,000 light years away from Earth. It's about 100 times more massive than our Sun - one of the most massive known - and it shines about 5 million times brighter than the Sun. It's surrounded by an unusual cloud of material known as the Homunculus Nebula, which astronomers believe was created by successive explosions on the star's surface. The Gemini Observatory has revealed a shockwave of expanding material moving through space at 500 km/second (310 miles/s).

View full article (http://www.universetoday.com/am/publish/eta_carinae_gemini.html)
What do you think about this story? post your comments below.

antoniseb
2006-Apr-14, 12:16 PM
Eta Carinae is pretty interesting. My son has a big poster of it on his wall. It will be interesting to get to the point where we can plot out its evolution toward its next big explosion.

Aknauta
2006-Apr-15, 04:33 PM
I'm curious about the "shockwave of expanding material moving through space at 500 km/second".
Could this shockwave, if it passed through our solar system, do catastrophic damage/alteration? If so what is the time span before this wave arrives?
My assumption is that there is an organized effort to detect threats to our system from outside of our solar system.

antoniseb
2006-Apr-15, 05:17 PM
what is the time span before this wave arrives?

Eta Carinae is about 5000 lightyears away. Light travels about ten trillion kilometers per year, so Eta Carinae is about fifty quadrillion kilometers away. The material coming out of it at 500 kilometers/sec will take 100 trillion seconds to get here. That is about three million years. When it gets here the amount of that material (if it were unimpeded by interstellar dust, and solar wind) would be about one microgram per square meter of our atmosphere. This material would take tens of thousands of years to accumulate, so we are talking about a flux of about a one proton per square cm per second. This is something we wouldn't detect, or be troubled by.

trinitree88
2006-Apr-15, 06:17 PM
The article referenced by Fraser is interesting. Mapping of the ejecta is by hydrogen molecular emission, and iron atomic emission profiles. The accumulation of iron in a massive star, such as Eta Carinae, is always fraught with peril. Last stages of a type 2 supernova with core collapse triggering it are caused by a relatively short-lived stage when iron begins accumulating in the nucleus. Older models for type 2's indicated as little as 6 months to a year from iron to boomtime.Newer models give ~ a decade.
The already noted presence of iron in Alnitak on Orion's Belt, led me to give it a few years at best, the same goes for Eta Carinae, I'll lay odds that Eta goes supernova in less than three years. I'll wager a hot fudge sundae....any takers? Pete.

antoniseb
2006-Apr-15, 06:26 PM
I'll lay odds that Eta goes supernova in less than three years. I'll wager a hot fudge sundae....any takers? Pete.
If you mean that it already has, and that we'll see it happen before April 15th, 2009, you're on. We don't live so far apart to make the settling of the bet difficult. I think we're thousands of years from that explosion.

trinitree88
2006-Apr-15, 09:36 PM
If you mean that it already has, and that we'll see it happen before April 15th, 2009, you're on. We don't live so far apart to make the settling of the bet difficult. I think we're thousands of years from that explosion.

:lol: Done deal. There are a lot fewer risk-takers in the forum than in my classrooms. I've won & lost a bunch of small bets through the years....and have tried to make the point with the kids.....the breakthroughs seldom come from taking the party-line...and not sticking your neck out a bit. Tax day...three years hence it is Antoniseb. Good luck. Pete.

antoniseb
2006-Apr-15, 09:43 PM
three years hence it is Antoniseb.
Or sooner if you're right.

five_distinct
2006-Apr-17, 03:14 PM
Can I get odds on this? I'm calling Vegas.

trinitree88
2006-Apr-17, 09:15 PM
Can I get odds on this? I'm calling Vegas.


Nope, nope, nope! straight up...one hot fudge sundae...and two bets is my limit, I am a poor school-teacher you know..(of course students always enjoy the gloating more than the prize...:lol: ) Pete.

RussT
2006-Apr-17, 11:25 PM
trinitree88
Senior Member

Pete, I hope you win this bet this week!!!

Why, because this would and will prove, beyond a shadow of a doubt, that long GRB's are NOT what everyone thinks they are!!!

RussT
2006-Apr-20, 09:31 AM
trinitree88
Senior Member

Pete, I hope you win this bet this week!!!

Why, because this would and will prove, beyond a shadow of a doubt, that long GRB's are NOT what everyone thinks they are!!!

trinitree88, isn't a star of this size supposed to be a long GRB when it goes supernova, or should I say Hypernova?

trinitree88
2006-Apr-20, 11:26 AM
trinitree88, isn't a star of this size supposed to be a long GRB when it goes supernova, or should I say Hypernova?

Thanks for the support RussT. However I can only say maybe with regard to the long GRB. Since the mainstream thought is that they are beamed, and there are a lot of angles in a sphere...chances of us catching the beam are slim. My recollection of Eta C is an hourglass..pretty much side view. Parity effects would suggest that axis for the beam..not directed towards us, though there may be some light side-scattering as the envelope opens up. So yes there should be a GRB, and no to a definitive answer on the association. Viewing angle is critical here. Pete.

RussT
2006-Apr-22, 01:40 AM
And because of this 'Beaming', mainstream also predicts that there are 450 to 500 of these Hypernova events per day...absolutely incredible, considering how many regular supernova 1a and II events we actually see! And, oh yeah,
btw, it is also absolutely incredible that we can see a 'single' star do this from 12 to 13 billion light years away!

antoniseb
2006-Apr-22, 11:44 AM
And because of this 'Beaming', mainstream also predicts that there are 450 to 500 of these Hypernova events per day

I'm not sure what you are saying. Are you saying we should be seeing that many because beams concentrate energy so well (a contradiction with observation), or that since we see beams for about one a day, that that implies 450 to 500 per day universe-wide?

RussT
2006-Apr-23, 11:05 AM
I'm not sure what you are saying. Are you saying we should be seeing that many because beams concentrate energy so well (a contradiction with observation), or that since we see beams for about one a day, that that implies 450 to 500 per day universe-wide?


[or that since we see beams for about one a day, that that implies 450 to 500 per day universe-wide]

This one.

antoniseb
2006-Apr-23, 02:29 PM
Thanks.

To me it seems odd that with the huge numbers of stars in the visible universe that we only see several GRBs a week. I'm guessing that the earliest stars must have had their blasts (if they had them) before the end of the last opaque era of the universe.

George
2006-Apr-23, 07:11 PM
Nope, nope, nope! straight up...one hot fudge sundae...and two bets is my limit, I am a poor school-teacher you know..(of course students always enjoy the gloating more than the prize...:lol: ) Pete.
So who's the second beter? If it's available, count me in, but don't mail it to me if I win. :) We'll pay off at the subsequent heliochromology seminar. ;)

RussT
2006-Apr-23, 08:24 PM
Thanks.

To me it seems odd that with the huge numbers of stars in the visible universe that we only see several GRBs a week. I'm guessing that the earliest stars must have had their blasts (if they had them) before the end of the last opaque era of the universe.

The oddness you refer to here is actually a telling story, and the predicted 450 to 500 1c off axis beaming numbers, is a good way to test and see that "Beaming" for long GRB's is wrong.

As I wrote in the SN1a thread, since they did not have the concept in 98', that there should be these 450/500 off axis beamed long GRB's/1c's, they should have found "WAY" more sn1a/1c's than they did!

trinitree88
2006-Apr-24, 10:30 PM
So who's the second beter? If it's available, count me in, but don't mail it to me if I win. :) We'll pay off at the subsequent heliochromology seminar. ;)

Ok, George, you're on, too, as second bettor....with Antoniseb. heliochromology seminar..hmmm...it was spectroscopy interests set all this stuff off, years ago. Good luck to both of you. Pete.

George
2006-Apr-25, 12:40 AM
Ok, George, you're on, too, as second bettor....with Antoniseb. heliochromology seminar..hmmm...it was spectroscopy interests set all this stuff off, years ago. Good luck to both of you. Pete.
Deal it is, then. [It was the BA's stuff on the sun's color for me.]

Looks like two of us will have a blast, unless you do, of course. Frankly, I hope I loose. Good luck. I'll expect a cherry on top. [fwiw, admittedly, I am too weak on this subject to gloat.]

Will you be posting Fe values all the way till April 16th (the likely day now). :)

Tensor
2006-Apr-25, 03:37 AM
I'm not sure what you are saying. Are you saying we should be seeing that many because beams concentrate energy so well (a contradiction with observation), or that since we see beams for about one a day, that that implies 450 to 500 per day universe-wide?

Here's your answer:

This paper (http://arxiv.org/PS_cache/astro-ph/pdf/0307/0307058.pdf) which (through a completely different method corroborates a paper by Frail in The astrophysical journal in 2001, check the referrences in the paper for Frail's paper) shows the number of actual to seen long GRBs to unseen GRBs is around 450-500 to 1 (for every observed long GRB there are 450-500 which are not observed due to the beams missing us)

RussT
2006-Apr-26, 12:15 AM
Yeah, and they should start finding thousands of them any day now, because if it is 500 a day, that would be 1,825,000 in just 10 years!

MG1962A
2006-Apr-26, 09:30 AM
It is interesting that the mass has been stepped now quite a bit from the figures of only a few years ago - usually 110 to as high as 135 solar masses.

Also has there been a definitive resolution of the binary theory to account for the mass issues with the star?

sol88
2006-Jun-14, 04:49 AM
A "thick," warm inner dust shell traced by [Fe II] emission is surrounded by a cooler and denser outer shell that is traced by strong H2 emission.

So how did the Fe II emissions end up expanding in a shell from material released from these "explosions"?? Surley as the current model of the Sun stands Fe has to come from the core? I'm confused :(

Sol

trinitree88
2006-Jun-15, 01:33 AM
So how did the Fe II emissions end up expanding in a shell from material released from these "explosions"?? Surley as the current model of the Sun stands Fe has to come from the core? I'm confused :(

Sol

Sol. Stuff mixes through convection cells. It was thought that it took a long time, but some other posts indicated that there was more mixing than models accounted for....so when the explosions occurred...some iron was ejected too. You can Google iron in stellar atmospheres.
The shape of the nebula also suggests that this is not a surface effect...but a bipolar jet...so taking some interior material along makes more sense. Pete.

sol88
2006-Jun-15, 07:06 AM
Sol. Stuff mixes through convection cells. It was thought that it took a long time, but some other posts indicated that there was more mixing than models accounted for....so when the explosions occurred...some iron was ejected too. You can Google iron in stellar atmospheres.
The shape of the nebula also suggests that this is not a surface effect...but a bipolar jet...so taking some interior material along makes more sense. Pete.

Yes that explains it, I was under the impression that stars are very much similer to our own local one.

George
2006-Jun-16, 12:35 PM
Do we know if our sun ever puffed? Assuming it did early in its history, would we see it?

trinitree88
2006-Jun-17, 11:36 AM
Do we know if our sun ever puffed? Assuming it did early in its history, would we see it?

George. I don't think I've ever seen that modeled...maybe someone else has. The composition of the sun would not suggest an exotic isotopic distribution. On the other hand, supenovae have a variety of compositions depending upon the chracteristics of their progenotors.....some distribute iron whiskers far and wide...a good source of smooth spectral energy distribution radiation..though usually not long-lived.:think:

George
2006-Jun-17, 03:29 PM
George. I don't think I've ever seen that modeled...maybe someone else has. The composition of the sun would not suggest an exotic isotopic distribution. On the other hand, supenovae have a variety of compositions depending upon the chracteristics of their progenotors.....some distribute iron whiskers far and wide...a good source of smooth spectral energy distribution radiation..though usually not long-lived.:think:
[Thanks. The mis-behavior of nascent solar-sized stars is of interest to me.]

Are you saying the progenitor is very close to a blackbody radiator initially? Does its atmosphere develop absorption bands later?

trinitree88
2006-Jun-17, 09:35 PM
[Thanks. The mis-behavior of nascent solar-sized stars is of interest to me.]

Are you saying the progenitor is very close to a blackbody radiator initially? Does its atmosphere develop absorption bands later?

George. No, not the progenitor. Post-mortem. There are supernova remnants that deconvolute their onion-layer isotopic morphology....and are filled with iron whiskers, others seem to mix the whiskers with the ejecta, or grow them over time. You'd think from the chemical composition, that the iron would form sulfides, silicates, oxides, nitrides, but ejecta kinematics, coupled with magnetic fields, seems to offer the opportunity for the excess hydrogen involved (the primary ejectant) to produce regions where there is a reducing atmosphere (hot hydrogen rapidly reduces black copper oxide to metallic copper in a high school lab)...yielding iron. Over time, needles and whiskers can grow. They can be pretty blackbody.

George
2006-Jun-17, 09:58 PM
George. No, not the progenitor. Post-mortem. There are supernova remnants that deconvolute their onion-layer isotopic morphology....and are filled with iron whiskers, others seem to mix the whiskers with the ejecta, or grow them over time. You'd think from the chemical composition, that the iron would form sulfides, silicates, oxides, nitrides, but ejecta kinematics, coupled with magnetic fields, seems to offer the opportunity for the excess hydrogen involved (the primary ejectant) to produce regions where there is a reducing atmosphere (hot hydrogen rapidly reduces black copper oxide to metallic copper in a high school lab)...yielding iron. Over time, needles and whiskers can grow. They can be pretty blackbody.
Thanks, that's interesing and surprising. Have other magnetic molecules been found to exhibit whiskers, too?

I am still puzzled about the blackbody emission, are you saying the iron itself can produce near bb radiation? :doh:

Blob
2006-Sep-12, 10:30 AM
Title: The Chrysalis Opens? Photometry from the Eta Carinae HST Treasury Project, 2002-2006
Authors: J.C. Martin, Kris Davidson, M.D. Koppelman

During the past decade Eta Car has brightened markedly, possibly indicating a change of state. Here we summarize photometry gathered by the Hubble Space Telescope as part of the HST Treasury Project on this object. Our data include STIS/CCD acquisition images, ACS/HRC images in four filters, and synthetic photometry in flux-calibrated STIS spectra. The HST's spatial resolution allows us to examine the central star separate from the bright circumstellar ejecta. Its apparent brightness continued to increase briskly during 2002--06, especially after the mid-2003 spectroscopic event. If this trend continues, the central star will soon become brighter than its ejecta, quite different from the state that existed only a few years ago. One precedent may be the rapid change observed in 1938--1953. We conjecture that the star's mass-loss rate has been decreasing throughout the past century.

Read more (http://arxiv.org/PS_cache/astro-ph/pdf/0609/0609295.pdf) (128kb, PDF)

antoniseb
2006-Sep-12, 01:39 PM
That was an interesting paper. Eta Carina is a very interesting object, and one of a few fairly nearby stars that we can watch as it evolves through some critical parts. It will be interesting to observe this with higher spatial resolution in the future.