IAA-CSIC: Stars Akin to the Sun Also Explode When They Die

[bystander]

Stars Akin to the Sun Also Explode When They Die
Instituto de Astrofísica de Andalucía | Consejo Superior de Investigaciones Científicas | 2015 Feb 17

IRAS 15103-5754, a star observed as it was turning into a planetary nebula, yields new clues as to the death of stars akin to the sun

[i]Radio and IR image of IRAS 15103-5754 showing the velocity of the material in the jet.[/i]

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The birth of planetary nebulae, resulting from the death of low and intermediate mass stars, is usually thought of as a slow process, in contrast with the intense supernovae that massive stars produce. But a recent study led by researchers at the Institute of Astrophysics of Andalusia (IAA-CSIC) in collaboration with the Center for Astrobiology (CAB, CSIC/INTA) has revealed the fact that explosive phenomena also intervene in the formation of planetary nebulae.

"In a few thousand million years, the sun will exhaust its nuclear fuel, expand into a red giant and eject a major part of its mass. The final result will be a white dwarf surrounded by a glowing planetary nebula. Even though every star with a mass below ten solar masses goes through this short but important final transition, many details of the process still evade us”, says José Francisco Gómez, IAA-CSIC researcher in charge of the project.

The study of IRAS 15103-5754, part of a group of sixteen objects known as ‘water fountains’, has yielded important clues concerning this final stage. ‘Water fountains’ are mature stars in a state of transition from red giants to planetary nebulae which display jets of ejected material that can be detected from intense radiation produced by water vapor molecules (water maser emission). ...

This study has established the importance of ‘water fountains’ in understanding how the symmetry of stars is broken in the final stages of their lives, and thus to shed light on the outstanding variety of planetary nebulae that we encounter.

The first "water fountain" collimated outflow in a planetary nebula - J.F. Gomez et al

• Astrophysical Journal 799(2) 186 (2015 Feb 01) DOI: 10.1088/0004-637X/799/2/186
  arXiv.org > astro-ph > arXiv:1412.2327 > 07 Dec 2014 (v1), 17 Dec 2014 (v2)

[BDanielMayfield]

Then a sizable percentage of the universe's oxygen must come from low massed stars that never go supernova. This also would help to explain why O is the third most common element in the interstellar medium after hydrogen and helium.

Bruce

[Ann]

Ordinary red giants that do not explode as supernovas certainly contribute a lot of heavy elements to the universe. As they near the end of their lives, they produce a cocktail of elements and even molecules.

Ann

[BDanielMayfield]

Ordinary red giants that do not explode as supernovas certainly contribute a lot of heavy elements to the universe. As they near the end of their lives, they produce a cocktail of elements and even molecules.

Ann

But, which elements, and how heavy? This would have to be a function of a star's starting mass. The heaviest elements can only come from supernovas.

Bruce

[Ann]

Ordinary red giants that do not explode as supernovas certainly contribute a lot of heavy elements to the universe. As they near the end of their lives, they produce a cocktail of elements and even molecules.

Ann

But, which elements, and how heavy? This would have to be a function of a star's starting mass. The heaviest elements can only come from supernovas.

Bruce

Check out this paper by Taïssa Danilovich.

Here is a quote from the abstract:

Low- and intermediate-mass stars will all eventually enter the asymptotic giant branch
(AGB) phase. AGB stars experience intense mass-loss, generating a significant fraction
of the dust and atomic and molecular matter that enriches the interstellar medium. AGB
stars are also responsible for the production of about half of all elements heavier than
iron.

Ann

[BDanielMayfield]

Check out this paper by Taïssa Danilovich.

I will. Thanks Ann.

Here is a quote from the abstract:

Low- and intermediate-mass stars will all eventually enter the asymptotic giant branch
(AGB) phase. AGB stars experience intense mass-loss, generating a significant fraction
of the dust and atomic and molecular matter that enriches the interstellar medium.

So far so good, but ...

AGB stars are also responsible for the production of about half of all elements heavier than
iron.

Say what This seems wrong to me. I thought that only stars that go SN can generate the extreme conditions required to create heavier than iron elements. Got some reading to do ...

Bruce

[Chris Peterson]

Say what :?: This seems wrong to me. I thought that only stars that go SN can generate the extreme conditions required to create heavier than iron elements.

Not quite so. You can't produce energy by fusing iron or anything heavier. So the life of a star ends once it is mostly iron. But there are other nucleosynthesis pathways by which heavier elements can be created. It just takes more energy than it releases. So even low mass stars like the Sun may produce some heavy elements at the end of its life, especially in the processes that lead to planetary nebula formation. Some elements, like copper and barium, are produced only in massive stars and not in supernovas at all.

[BDanielMayfield]

I thought that only stars that go SN can generate the extreme conditions required to create heavier than iron elements.

Not quite so. You can't produce energy by fusing iron or anything heavier. So the life of a star ends once it is mostly iron.

Yes, I knew these these things and wasn't suggesting otherwise.

But there are other nucleosynthesis pathways by which heavier elements can be created. It just takes more energy than it releases. So even low mass stars like the Sun may produce some heavy elements at the end of its life, especially in the processes that lead to planetary nebula formation. Some elements, like copper and barium, are produced only in massive stars and not in supernovas at all.

This I'm happy to learn, as discovering how all the elements have come to be is one of my key interests in astronomy. Thanks.

But, how would you judge this statement:

AGB stars are also responsible for the production of about half of all elements heavier than iron.

[Chris Peterson]

But, how would you judge this statement:

AGB stars are also responsible for the production of about half of all elements heavier than iron.

No strong opinion. The number is higher than I would have expected, but this isn't my area of expertise. Then again, the statement is made in passing in a paper about a different subject. The statement is unreferenced, but appears to have been cribbed from the Wikipedia article on s-process nucleosynthesis- also unreferenced. Furthermore, s-process nucleosynthesis also occurs in very massive stars, and the comment isn't clear: the paper says half the elements heavier than iron, the Wikipedia article says half of the isotopes of the elements heavier than iron. Those are quite different things.

The paper is a thesis for a degree that is similar to a Master of Science, not requiring any original research. I don't know the degree to which it is reviewed or defended, but I would not consider it a very solid reference for the statement- especially given the apparent connection to an unreferenced Wikipedia claim (not that I have a problem with Wikipedia articles, but without a reference, I'm not going to take the claim too seriously).