Comments on: Double dipped supernova

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By: Astrolink [Global Edition] » Astrosphere for June 15, 2007 | Latest astronomy news in 11 languages

Fri, 15 Jun 2007 19:40:28 +0000

[...] I covered the double supernova here. Phil Plait from Bad Astronomy has a great description of it was well. [...]

By: Peter Hornby

Peter Hornby — Fri, 15 Jun 2007 18:13:07 +0000

To be strictly accurate, the previous major outburst of Eta Carinae was in the 1830′s and 1840′s, not the 1870′s. The star reached magnitude -1 (brighter than Canopus and only half a magnitude down on Sirius) in 1843.

By: JC

JC — Fri, 15 Jun 2007 15:05:00 +0000

Yes, I’m curious as well…what makes you set Eta Car apart from other luminous blue variables? I know little about this, but I thought it was just considered a singularly spectacular example of that class.

By: Astrogeek

Astrogeek — Fri, 15 Jun 2007 15:04:27 +0000

Brian/Gary;

I’m not certain, but I think an abundance of helium is expected because of the sheer size of the H-burning zone in these hyper-massive stars, and because of the upheavals expected in their evolution.

The presence of heavy elements causes these massive stars to blow off mass during the formation phase. I’m not clear on why that is, but I’ve seen it referenced several times. Something about the presence of heavy elements making the solar winds more efficient at carving out a hollow in the proto-stellar gas cloud.

Thats also why we think that Pop. III stars could get monstrously huge (perhaps up to about 500Msol) and why that’s not possible in Pop. II or Pop. I stars.

By: jackd

jackd — Fri, 15 Jun 2007 14:49:14 +0000

I’m missing something here. What is it that makes Eta Carinae singular? Its size is amazing, but obviously not unique. The fact that it blew off so much mass is awe-inspiring, but that’s an effect, not a quality. So what is it? I assume we must know something about the two monster stars recently discovered that tells us that they don’t match Eta C – and it wouldn’t just be the lack of an ejected nebula, since that could happen tomorrow, right?

Maybe I’m just reading too much into your statement, but I do feel that you’ve said something I just don’t understand.

By: Gary Ansorge

Gary Ansorge — Fri, 15 Jun 2007 14:04:17 +0000

Helium comes from the rapid fusing of hydrogen in these super massive stars. At the mass indicated, the life span would be measured in millions rather than billions, of years. It must have collected from a glob of mostly Hydrogen, rather than from the detritus of previous stars going blowy-uppy, which would have left traces of heavy metals in Eta-C.

I wonder how the metal traces may affect the evolution of stars. Perhaps they slow fusion rates, by acting as energy absorbers??? Just a thought,,,

Gary 7

By: Brian

Brian — Fri, 15 Jun 2007 13:31:58 +0000

Thanks BA. I am always greedy for more. Why is an abundance of helium expected in a very high mass star?

By: Ed Davies

Ed Davies — Fri, 15 Jun 2007 11:57:17 +0000

Kullat: “singular” here is being used to mean “one of a kind” (i.e., unlike almost any other stars), not “not part of a multiple star system”.

By: Kullat Nunu

Kullat Nunu — Fri, 15 Jun 2007 11:18:49 +0000

Eta Car is a singular star in our Galaxy…

Once a while there are reports that its binarity is confirmed… a companion could explain its observed periodicity. But IMHO it doesn’t feel right… Eta Carinae is supposed to be a lone superhypergiant.

By: Alan

Alan — Fri, 15 Jun 2007 05:42:56 +0000

Allan, the star in the picture is not Eta Carinae. He said the distance to the start in the picture above is about 80 million light years. Earlier, he mentioned it was part of the galaxy UGC 4904 (78 million LY). In the first paragraph, he describes Eta Carinae, a star in our own galaxy, as being 7000+ light years away. I think Phil got everything right.

By: Allan

Allan — Fri, 15 Jun 2007 05:12:16 +0000

Your estimated of Eta Car distance from earth is stated at 80 million light years. This seemed excessive to me so I entered “Eta Carinae distance from earth” in my google search engine and got a series of estimates ranging from 7,000 lightyears to 9,000 lightyears. Not close enough to do anything catastropic to Earth. Could you have meant 8,000 lightyears rather than 80 million lightyears?

By: Rick

Rick — Fri, 15 Jun 2007 04:00:04 +0000

I truly hope that one day I will get to witness one of those rare astronomical events like a nova visible in the day, or a comet that is truly awesome to the naked eye (I did see one a few years ago, but it was viewable only in the most darkest locations and very dim even then), or one of those meteor showers that rains hundreds or thousands of meteors a minute.

Perhaps Eta Carin will go off in my lifetime … that looks like it would be a real treat.

By: elgarak

elgarak — Fri, 15 Jun 2007 03:30:19 +0000

Just a minor nitpick … Shouldn’t the name be Eta Carin[b]ae[/b]?

By: Mike Haubrich, FCD

Mike Haubrich, FCD — Fri, 15 Jun 2007 03:24:42 +0000

Your post made me curious about whether the age of the UGC 4904 star has been estimated to be at the time that it went kablooie. Does the high content of helium mean that it was pretty old, or does it mean that it had formed from the detritus of several other “old” stars?