Why there are only 45 interstellar dust particles?

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CunhuaiZheng
Posts: 1
Joined: Tue Aug 08, 2006 7:40 pm

Why there are only 45 interstellar dust particles?

Post by CunhuaiZheng »

Why there are only 45 interstellar dust particles in 1,000 square centimeters?I think the rate is too low?
And also I wanna to know if the aerogel collector is bigger,for example,1 square meter, that we will get more stardusts,am I right?But why
didn't it?
Thank you!
--CunhuaiZheng

Jwb52z
Posts: 61
Joined: Thu Aug 03, 2006 5:05 am

Post by Jwb52z »

Here's the most simple answer I can think of to answer your question. Dust is very very small. Outer Space is HUGE. There's nothing to stop the dust from spreading out in any direction in space until it hits something else in space. Consequently, it isn't likely to be more plentiful or compact than a certain amount.

bmendez
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Post by bmendez »

The average density of interstellar dust particles in the part of the Solar System where they were collected is about 1 particle per cubic kilometer. This was independently measured by two previous NASA spacecrafts, Galileo and Ulysses.

The collector area is about 1000 square centimeters and it collected for about 6.5 months moving at a speed relative to the interstellar dust stream of 20 km/s. When you calculate how many particles should have been collected, the number is 45.

Incidentally, I'm making up a math problem for students to do this calculation as part of a lesson guide for Stardust@home.

Yes, if the collector had been bigger, it would have collected more particles.

-Bryan

P.S. This topic belong more in the Discussion forum so I'm moving it there.
"I am made from the dust of the stars, and the oceans flow in my veins"
- RUSH

nexguy
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Joined: Tue Aug 01, 2006 6:44 am
Location: Texas

Post by nexguy »

I would imagine that stellar dust particals would come in pairs or small groups "sometimes" due to their attraction to each other through static electricity. This might mean that the "groups" are farther apart, but it would be nice to see more than one partical per track.

cosmicrocker
Posts: 11
Joined: Sat Aug 05, 2006 8:10 am

Post by cosmicrocker »

Interesting. If 45 is the correct number, then the dust density must be about 1.31 particles/km^3. According to your numbers, the volume swept by the collector was 34.187 km^3.

See volume calculation here: http://www.google.com/search?hl=en&q=10 ... +in+km%5E3

(edited: I guess the url tags don't work.)
...Tom

visit #space on IRC.freenode.net

geckzilla
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Joined: Mon Aug 07, 2006 11:05 am

Post by geckzilla »

Here you go cosmic, tinyurled it for you. :)
http://tinyurl.com/ztr4f

cosmicrocker
Posts: 11
Joined: Sat Aug 05, 2006 8:10 am

Post by cosmicrocker »

Thanks, geckzilla. I guess the point we should all take home is that very few stardust tracks are to be expected over the entire tile array. Also note that only about 15-20% of the tiles have been made into available movies.

http://stardustathome.ssl.berkeley.edu/ ... c.php?t=78

So only about 10 tracks would be predicted to have been found in all of the work people have done so far. It appears that the spatial particle density in the above equation was not over-estimated. Perhaps no stardust tracks have been found yet. I guess we had better keep dusting. :)
...Tom

visit #space on IRC.freenode.net

JOC
Posts: 40
Joined: Mon Jul 31, 2006 8:59 pm

Post by JOC »

As you mention, I too wonder if we have found 10 particles or so. Surely we must have found some.

Unless, of course, the % of bad-focus has been unfortunately high. Still, even so, if you said proper coverage on even half of those scanned so far(and that'd be quite conservative perhaps), we'd expect maybe ~5 genuine particles!!...

Let's hope so!!
Twinkle, twinkle, little dust!
How I wonder which to trust!
From stars above the world you fell!
Buried like treasure in aerogel.

alexz
Posts: 18
Joined: Thu Aug 03, 2006 7:43 pm

Post by alexz »

Entering that data into google gives 34.2

Google : what is 1 divided by (1000 meters times 1000 meters times 1000 meters) times 1000 square centimeters times 6.5 months times 20 kilometers per second

Then again, the '1' is only one significant digit.

JOC
Posts: 40
Joined: Mon Jul 31, 2006 8:59 pm

Post by JOC »

I think you've answered your own question, alexz. [as did cosmicrocker, from the other angle]

With an expectation of only up to 10 genuine tracks in the processing so far... Even less, given the bad-focus movies...
That's on the order of maybe 1 per 1000 people looking for a week!


(1 track per 200 people, at final say, wouldn't be bad though!!!)


PS -- quote:"1 particle per cubic kilometer" -- what a tremendous mental picture that is!

:-)
Twinkle, twinkle, little dust!
How I wonder which to trust!
From stars above the world you fell!
Buried like treasure in aerogel.

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