I've been waiting for others to comment on the 20th Jan Update and the team's latest paper regarding analysis of "Midnight" tracks and Bruce Hudson's "Orion" particle in particular, but silence so far. First of all, I feel that congratulations are due to the team for having reached this point.
DanZ has recently posted references in the Community section to media articles about the paper, from Nature and BBC Science. Both make good reading, and are to be commended in stressing Andrew Westphal's cautionary comments regarding the whole issue.
Meanwhile, the BBC report emphasises the amorphous mixture of several unusual elements within the particle (and mentions the second particle "Sirius" evident in track 7663035V1), while Nature simply talks of "hints of a glassy, amorphous shape that is rich in aluminium" (which to my mind would suggest a micrometeorite fragment embedding in the glassy aerogel after impacting the aluminium collector).
I therefore re-read the paper to see how elemental abundances had been estimated. They are all quoted in terms of a ratio to iron, e.g.
Cr/Fe, Mn/Fe, Se/Fe, etc., but without mention of Al (aluminium) as a component at all that I could find! The benchmark for these ratios
seems to be something called "C1", yet no explanation of this term is given (would that be elemental carbon or what?)
Dan, I'm clearly out of my depth here, but suspect I'm not alone amongst regular dusters. May I appeal for some enlightenment about the
basics of such chemical analyses, so we can follow the Orion story, and whatever may follow it, with a bit more understanding?
John
Orion - first interstellar candidate?
Moderators: Stardust@home Team, DustMods
Re: Orion - first interstellar candidate?
Hi John,
Great questions! As far as I know, CI (as in the letter "i", not the number "1") refers to "CI-like" (i.e., like the CI group of meteorites, named after the Ivuna meteorite; see: http://en.wikipedia.org/wiki/Carbonaceous_chondrite ). As far as the aluminum goes, I asked the very same questions when I first learned of it. Turns out what they found is non-metallic aluminum. Now I need to double-check and get back to you, but I believe that means aluminum in its elemental state (as apposed to aluminum metal that is aluminum oxide or Al2O3). However, I may have misinterpreted.
When I get more info, I'll post again here right away. Also, please note that another video update is coming soon that addresses all of this.
Thanks for hanging in there!
Dan
Great questions! As far as I know, CI (as in the letter "i", not the number "1") refers to "CI-like" (i.e., like the CI group of meteorites, named after the Ivuna meteorite; see: http://en.wikipedia.org/wiki/Carbonaceous_chondrite ). As far as the aluminum goes, I asked the very same questions when I first learned of it. Turns out what they found is non-metallic aluminum. Now I need to double-check and get back to you, but I believe that means aluminum in its elemental state (as apposed to aluminum metal that is aluminum oxide or Al2O3). However, I may have misinterpreted.
When I get more info, I'll post again here right away. Also, please note that another video update is coming soon that addresses all of this.
Thanks for hanging in there!
Dan
Re: Orion - first interstellar candidate?
John,
Here's some follow-up as promised:
There is no mention of Al in the abstract because at the time of the abstract deadline the team had no measurements of Al. Now we do, and as mentioned, the Al is non-metallic Al. But we don't know yet what phase it is.
Things will be made somewhat clearer when Update #6 is posted. When that happens, I'll provide the link here.
Dan
Here's some follow-up as promised:
There is no mention of Al in the abstract because at the time of the abstract deadline the team had no measurements of Al. Now we do, and as mentioned, the Al is non-metallic Al. But we don't know yet what phase it is.
Things will be made somewhat clearer when Update #6 is posted. When that happens, I'll provide the link here.
Dan
Re: Orion - first interstellar candidate?
As promised, here's the link to Update #6: http://stardustathome.ssl.berkeley.edu/ispe_update/#sixThings will be made somewhat clearer when Update #6 is posted. When that happens, I'll provide the link here.
But you should also check out the latest blog entry at http://stardustathome.ssl.berkeley.edu/blog.php
As always, thanks for your patience!
Dan