[AZ-Observing] Re: Thermal Brightening from the Impactor?
- From: "Stanley A. Gorodenski" <stan_gorodenski@xxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Tue, 05 Jul 2005 21:05:03 -0800
Opps. When I said "or over 5 times the speed of the ejecta" I meant to
say the Impactor not ejecta.
Stanley A. Gorodenski wrote:
>Today in S&T I read the following:
>
>"The following was posted by Jeff Schroeder at Wrightwood:
>Two minutes after the predicted impact time, I saw a faint unstructured
>spot appear that was about 10 to 15 arcseconds wide."
>
>In a previous email message to Az-Observing before the impact event I
>assumed that what we would see visually is reflected sunlight off the
>ejecta. In that message I assumed the ejecta travels the same speed as
>the Impactor, i.e., 6.3 miles per second. I calculated that in 30
>minutes the ejecta would subtend an arc angle of 0.47 arc minutes or
>about 28 arc seconds, and that this probably would be able to be
>observed visually from Earth.
>
>However, if Jeff Scroeder actually observed a spot at least 10 arc
>seconds wide, this would mean the ejecta was traveling at a minimum of
>33.5 miles per second, or over 5 times the speed of the ejecta. If
>Jeff's observations are accurate with respect to size, and if it is not
>possible for ejecta to travel this much faster than the speed of an
>impactor (be it _the_ Impactor or a chunk of rock), than this says that
>the impact caused an intense thermal light flash that was diffused by
>the coma surrounding the nucleus into a much larger area then the actual
>ejecta. If this is a valid explanation, then what Jeff observed was this
>diffused glow, and not the actual ejecta. Any thoughts on this?
>Stan
>
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