Where is Sirius?

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elainekeefe
Posts: 190
Joined: Fri Aug 04, 2006 4:38 am
Location: Massachusetts, USA

Where is Sirius?

Post by elainekeefe »

I hope one of you more knowledgeable dusters can explain the following to me:

From the most recent blog entry (my italics and underlines):

At the 2010 Meteoritical Society Conference in New York, we reported on the further analysis of track 30 (Orion and Sirius), and reported the exciting discovery of two more promising interstellar dust candidates, tracks 34 and 37. Track 30 was analyzed by Alex Simionovici, Laurence Lemelle, and colleagues on beamline ID22 at the European Radiation SynchrotronFacility (ESRF). Alex and his colleagues oriented track 30 so that Orion and Sirius could be analyzed separately. X-ray fluorescence spectra showed the presence in each of iron, chromium, nickel and manganese. We already knew that the major elements present are aluminum in Orion and magnesium in Sirius. Orion appears to contain crystalline material.

I assumed when I first saw the Orion and Sirius candidate, that one of the two particles, or "dots" was Orion and the other was Sirius. Then I read the following report from DanZ, explaining that the larger of the two dots was just condensed aerogel:

(From this thread):

http://stardustathome.ssl.berkeley.edu/ ... dff#p17954

Here's your answer John!:

"This duster is correct: the condensed aerogel blob is in the track. It is part of, and formed with, the track. It's not a blemish, which sounds more like a defect. We know it's condensed aerogel because we analyzed it at the STXM beamline at ALS 11.0.2, LBL. The details of the analysis are in Andrew's Update of narrated slides [see number six at the bottom]. In the slide-set is a composite of x-ray absorption images making up a picture of the entire track, including the blob. We see condensed aerogel (i.e. same composition, but more dense than surrounding aerogel) all the time in the cometary tracks. Every track has these condensed aerogel blobs in the (much larger) track walls. In the case of Orion, we don't know the impact speed or the impactor's mass, so it's difficult to model the physics that causes the mid-track aerogel re-deposit that we've seen in both Track 29 & 30. We don't yet have any lab analogs of midnight tracks."


So, if the second "dot" is just aerogel, can someone tell me please where I can find Sirius? Or have they for some reason named and tested a blob of condensed aerogel?

Orion:

http://stardustathome.ssl.berkeley.edu/ ... e_id=76543

Thanks, Elaine
fjgiie
DustMod
Posts: 1253
Joined: Sat May 20, 2006 8:47 am
Location: Hampton, SC, US

Re: Where is Sirius?

Post by fjgiie »

It seems simple to me, a simple fella , ha, ha

The particles may be to small to see; we should click on the tracks.

whatcha thimk?

... again this is sort of a cop out answer - like there are other intelligent beings in the universe but we will never see them nor contact them bacause they are too far away; average distance between intelligence 2.4 billion light years.
jsmaje
Posts: 616
Joined: Tue Aug 15, 2006 8:39 am
Location: Manchester UK

Re: Where is Sirius?

Post by jsmaje »

Elaine, take a look again at Andrew Westphal's ISPE update no.6. Sirius was found in track 30 very close behind Orion (~ 3 microns) once the latter was examined in detail, is smaller and differs in composition. It is not the condensed aerogel blob (analysed seperately) which occurs a further ~ 20 microns earlier in the track.

I couldn't save the micrograph shown about two-thirds the way through the Quicktime presentation, but have made a (very) rough sketch of the salient features below. I therefore guess Sirius is more or less where indicated on the accompanying frame from movie 2736010V1:

Image Image
John
elainekeefe
Posts: 190
Joined: Fri Aug 04, 2006 4:38 am
Location: Massachusetts, USA

Re: Where is Sirius?

Post by elainekeefe »

fjgiie and jsmaje,

Thank you both for clearing that up. I'm sure (at least I hope) I was not the only one confused by that. I was able to find that diagram on Update 6 and take a screen shot so everyone can see for themselves (nice graphics, though, John): (I believe TP 1 is Orion and TP2 is Sirius.)

Image

Elaine

P.S. John, the url for the Updates page is the same for all, so yours comes up as Update 1. I copied the link given in the blog and was able to get the correct one (or you can just scroll down in yours):

http://stardustathome.ssl.berkeley.edu/ispe_update/#six
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