2 or more apparent tracks on same movie?

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Post by wonderdogxyz »

I found the last several posts in this threat to be among the most interesting and informative on the board. Thanks to all for the information! I also have wondered if the "stream" of particles originating from some unknown source could have been diverted from its expected route by a celestial body or other forces, resulting in the collector being placed in a “dry streambed”.
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Post by jsmaje »

Mitchell Criswell III wrote:If during the time of collection the majority of particles were being deflected by the solar wind magnetic field, could not the more massive particles that reached 2 AU have been deflected so as to strike the collector at an angle to the perpendicular? In other words, might a percentage of the so called high angle tracks (HATs) that we have found be the result of interstellar particles?
Sounds a good idea to me, thus accounting for their generally larger size but low numbers, as Ryan predicts.
I've yet to see any equivalently precise estimate having been made of the size, frequency and trajectories during the actual collector deployment of interplanetary particle impacts, spacecraft debris, etc., which were initially predicted to manifest themselves (exclusively?) as the HATs, and with which we might be able to compare experience so far. For example, are there any independent satellite IP-impact measurements at ~2 AU during that time?

The most recent particle candidates list I can find has only 14 entries for HATs, none of which have yet been analysed and probably aren't currently prioritised, as opposed to three of the 41 presumed-IS candidates listed (9267050V1, 9471219V1, 4589365V1). Quite why the other non-listed three (404198V1, 56372951V1, 3602277V1) of the six so far analysed also had priority is unexplained to my knowledge.

"I found the last several posts in this threat..."
No threat intended I'm sure ... :) !!

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IS dust impact direction

Post by ogliore »

Hi Mitch -
Very good question. The calculation of the direction of the IS dust flow was done by Frisch et al. in a 1999 paper in The Astrophysical Journal from the Ulysses data. The direction was determined statistically based on the rotation angle of the instrument and the number of hits recorded at a given angle. Frisch et al. assumed that the particles have straight trajectories through the heliosphere. This of course isn't the case, but the error they get from assuming a straight line trajectory they calculated to be smaller than their statistical error in determining the impact direction: ecliptic longitude = 259 +/- 20 degrees, ecliptic latitude = -8 +/- 10 degrees (one-sigma uncertainties). Now if the deflections during the Stardust collection are much larger than those during the Ulysses detection, this may mean that we'd have to increase the uncertainties on the latitude and longitude estimation, which means that the bounds on what we refer to as "normal incidence" would become broader. Your question is: would these bounds include what we call "high-angle" tracks now, tracks that we dismiss as non-interstellar? I would say with high certainty that the increased solar wind magnetic field deflection effect is not this great, and these high-angle tracks are well out of the uncertainty bounds of deflected IS particles. Of course to be more quantitative we'd need to model the trajectories better, and this is something that I'd look into once the model is completed.
Ryan Ogliore
Postdoctoral Scholar, Space Sciences Laboratory
University of California, Berkeley
Mitchell Criswell III
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Post by Mitchell Criswell III »

Hi Ryan,

Thanks for your quick and informative reply. As an amateur astrononer I continue to marvel at what we know and what we do not yet know. And I will continue to search for the allusive I.S. particles.

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