Huge comet outburst reported, 17P/Holmes |
Huge comet outburst reported, 17P/Holmes |
Oct 24 2007, 02:11 PM
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#1
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Junior Member Group: Members Posts: 30 Joined: 30-May 05 Member No.: 396 |
I didnt know in which category of the forum this should be reported:
http://www.fototime.com/%7BE39A64F6-CE74-4...%7D/picture.JPG http://perso.orange.fr/fkometes/images/com...422-9x5sz05.JPG Comet 17p/Holmes from 15 mag to 3!! Already visible to naked eye! |
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Oct 28 2007, 03:33 PM
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#2
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Junior Member Group: Members Posts: 98 Joined: 29-July 05 From: Amsterdam, NL Member No.: 448 |
According to a short article on SpaceWeather.com, the spherical cloud is now larger than Jupiter! (In absolute terms.) Also, the apparent brightness has been estimated to be ~2.1 or nearly that of Polaris, and "to the naked eye, it is no longer a simple point of light." We've had largely unfavorable conditions here in the Netherlands, but hopefully things clear up some night soon.
http://www.spaceweather.com/ |
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Oct 28 2007, 04:27 PM
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#3
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
The 3 frame animation and comparison to Jupiter image states the gas has an approx. 2.4 km/s mean velocity. Which velocity would that be? It can't be radial because 2.4 km/s gives over 200 000 km covered in just 1 day, while Jupiter's radius is 70-ish thousand km. The math doesn't add up somewhere. A figure of say 300 m/s sounds more plausible. -------------------- |
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Oct 28 2007, 08:25 PM
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#4
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Junior Member Group: Members Posts: 98 Joined: 29-July 05 From: Amsterdam, NL Member No.: 448 |
A figure of say 300 m/s sounds more plausible. I agree. Rough calculations for me yield velocities of ~360m/s and this number is more or less constant for the last three days (to within error). I also searched the literature and found nothing in the range of 2.4km/s for comet emission velocities. Most were at or less than 0.5km/s and this also seems to be the norm for comet gas emissions. What still strikes me with this comet is that the expanding cloud is spherical in shape--the gas and dust seems to be moving from the source outward largely uninhibited. Perhaps naively, I might have expected a more directed emission of the volatiles. Kohoutek 0.5km/s Hale-Bopp 0.4km/s LINEAR 1999 S4 0.5km/s Tempel 1 >0.16km/s (projected velocity) Anyway, more rain tonight... |
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