Was the Sun made in a supernova?
What is strange xenon and why is there a difference in the ratio of Xe136/134 in the solar wind and on Jupiter and is this significant?
There are 9 stable isotopes of Xenon as well as 20 or so that decay rapidly. (Isotopes are atoms which have the same number of protons, so the same chemical properties, but different numbers of neutrons in their nuclei. On the Earth, the abundances of different isotopes of Xenon have a particular ratio. For example the two least common isotopes on the Earth are Xe134 (10%) and Xe136 (8%). "Strange Xenon" seems to refer to the different isotope ratios found in meteorites, however it is not a commonly used term.
I suspect that you have been reading about Dr. Oliver Manuel's theories about the Sun being mostly made of iron. He uses the Xenon ratios to back up his ideas, claiming that the fact that they are different in Jupiter and the Solar Wind proves that the Solar System was made in a supernova explosion and that the Sun is made of iron.
The claim is that the strange xenon isotope mix in meteorites could not have been made unless the Solar System formed in a supernova explosion. In my opinion this does not follow. We know that the gas cloud from which our Solar System formed contained heavy metals, therefore must have had some remnant of several supernova explosions in it. The xenon mix could easilly be a tracer of that without requiring that the Solar System formed in a supernova. In fact Dr. Manuel's works on measuring the isotope ratios in meteorites has been very important in providing evidence that the gas cloud from which the solar system formed must have been enriched by more that one supernova.
The Xe136/134 ratio in Jupiter vs. that in the Solar Wind have been measured to be different. In Dr. Manuel's theory this is taken as proof that the central regions of the solar system were made from the inner part of a supernova, while the outer regions were made from the outer part. As far as I am aware no other scientist places such significance on such a minor detail. Isotope ratios are tricky to measure and even trickier to interpret so I would not want to base a theory on them. In my opinion the huge amount of evidence in favour of the standard scenario for the formation of the solar system (discussed in this answer) vastly outweighs this tiny point. Jupiter and the Sun are both extremely complex objects, with very complicated mixing of atoms. This could easilly vary the isotope ratios of xenon. I don't believe that the difference in ratios really has any significance.
Can I please refer you to this website on the scientific method. I would particularly like to ask you to read points 1.5: "Extraordinary evidence is needed for an extraordinary claim" and 1.7: "Galileo was persecuted, just like researchers into X today" (substitue "an iron Sun" for "X" if you please). I would finally like to encourage you to continue reading about all scientific theories, but try to read with a critical mind.
Thank you for your excellent reply. It was astute of you to connect this question to Oliver Manuel; you are right, I have been reading his papers and must admit a certain fascination about the idea but I think this fascination is based on "romantic" ideas, if I can use the term, rather than "the scientific process". You are the first, for me, to mention that the material from which our system was formed, may have come from not just one but several supernova although I assume you do not believe that our sun was formed from the core of one. My physics is weak so maybe you can help with with some nucleogenisis question: what is the process that created the "strange xenon" ratio that would be different from the ratio of xenon we see in the solar wind? Are you implying that there might be other ratios as yet unmeasured?
It is well accepted that the gas that our Sun and the solar system formed from must have been enriched by the products of more than one supernova, and, as I mentioned above some of Dr. Manuel's work on the abundance ratios in meteorites provided some of the first evidence for this scenario. We see supernova enrichment going on in other galaxies and other regions of our own galaxy - it seems that there is a strong connection between supernovae and star formation - maybe the shock wave from supernova is required to start the gas collapsing (or would certainly help). It's a very interesting feedback system. You are right that I don't think that Dr. Manuels ideas hold any weight though. I will stick with the tried and tested picture until some extraordinary evidence comes along to suggest otherwise.
I don't think that the isotope ratios of Xenon that are measured have any significance. The ratios produced in nucleosynthesis are due to fine tuning and exactly what you start with. Also the ratios are hard to measure and may be changed by mixing processes in the Sun (ie. heavier isotopes might preferentially fall to the centre of the Sun). I think that using these isotopes as the main piece of evidence for such an extraordinary claim is not scientifically sound.
January 2004 update: Dr. Manuel has replied to this answer listing more of the evidence he claims backs up his theory and requesting that it be posted here.. All theories deserve the right to be judged on the evidence alone, however we do not believe that this site is an appropriate forum for in depth scientific debate, and will leave scientists working on the area of Solar System formation to address the finer points of Dr. Manuel's theory. For the view of two such scientists check out this CNN article. Finally, as I mentioned above we encourage every to read about lots of interesting theories, but do so with a critical mind. If you want to read more of Dr. Manuel's opinions please visit his website. There is also this online discussion (which Dr. Manuel requested we link) hosted by Physlink
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
- Where is the supernova remnant that led to our solar system?
- What is the evidence supporting the nebula theory of Solar System formation?
- Does the Sun have an iron surface?
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 41433 times since August 26, 2002.
Last modified: March 31, 2004 11:01:18 AM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)