[Prev][Next][Index][Thread]
(meteorobs) P/2000 G1 & Vgeo
Lew Gramer wrote:
>>RA 75 to 80 deg, Dec -16 to -17, Vg 10 km/s, but date May 29th
>
> John, does the above mean your calculations show a geocentric velocity
> for the meteoroids from some putative stream associated with P/2000 G1
> LINEAR as being 10 km / sec? If so, then you should recheck your calc-
> ulations: My limited understanding is that 11 km/s is a hard minimum
> for Vg, thanks to Earth's gravity... ?
Hello Lew,
That bit should have read 10 to 15 km/s to give a range.
The software actually gives 11 km/s as an "exact" figure.
HOWEVER, Vgeo is a *vector* thingy, and as far as I know the lower limit to
speed is more to do with terminal velocity than Earth's gravity, ie what
the minimum speed is that still allows enough friction for burn up to occur
in the upper atmosphere. Anybody know better?
The micrometeoroids and Brownlee particles are smaller, so they float to
the ground, or in the atmosphere. I dunno what the limiting velocity is
for "average sized" meteor producing meteoroids. Does anybody else?
IMO lists the Camelopardalids as having Vgeo 6.8 km/s, though a book more
conservatively just said "less than 10 km/s". Meteor databases carry a few
meteors with Vgeo less than 10 km/s, even half a dozen down to about at one
and a half km/s, but as the errors are probably a few km/s, these slowest
handful are probably meaningless.
Actually, turning this upside down: I've never managed to get the full hang
of calculating orbits from RA, Dec, sol. long & Vgeo, nor ever managed to
find any software to do it for me!
The Camelopardalids are surely going to have a quite Earth-like orbit to
have Vgeo this low![?] IMO gives RA 118.7 deg, Dec 68.3, Sol.long 359.7,
Vgeo 6.8 km/s... ...anybody out there want to calculate an orbit from this?!
Cheers
John
JG, UK
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html
Follow-Ups: