[Prev][Next][Index][Thread]
(meteorobs) Excerpts from "CCNet 112/2000 - 1 November 2000"
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.ac.uk>
To: cambridge-conference <cambridge-conference@livjm.ac.uk>
Subject: CCNet, 1 November 2000
Date: Wed, 1 Nov 2000 09:54:04 -0000
CCNet 112/2000 - 1 November 2000
--------------------------------
[...]
(3) METEORIC CLOUD OF COMET TEMPLE-TUTTLE
R. Nakamura et al.
(4) METEORS, METEORITES & COSMIC DUST
F.J.M. Rietmeijer
[...]
=================================================================
(3) METEORIC CLOUD OF COMET TEMPLE-TUTTLE
R. Nakamura, Y. Fujii, M. Ishiguro, K. Morishige, S. Yokogawa, P.
Jenniskens, T. Mukai: The discovery of a faint glow of scattered sunlight
from the dust trail of the Leonid parent comet 55p/Tempel-Tuttle.
ASTROPHYSICAL JOURNAL 540: (2) 1172-1176, Part 1 SEP 10 2000
A meteoric cloud is the faint glow of sunlight scattered by small meteoroids
in the dust trail along the orbit of a comet as seen by an earthbound
observer. While these clouds were previously only known from anecdotes of
past meteor storms, we now report the detection of a meteoric cloud by
modern techniques in the direction of the dust trail of comet
55P/Tempel-Tuttle, the parent of the Leonid meteor stream. Our photometric
observations, performed on Mauna Kea, Hawaii, reveal the cloud as a local
enhancement in sky brightness during the Leonid shower in 1998. The radius
of the trail, deduced from the spatial extent of the cloud, is approximately
0.01 AU and is consistent with the spatial extent mapped out by historic
accounts of meteor storms. The brightness of the cloud is approximately
similar to 2%-3% of the background zodiacal light and cannot be explained by
simple model calculations based on the zenith hourly rate and population
index of the meteor stream in 1998. If the typical size of cloud particles
is 10 mu m and the albedo is 0.1, the brightness translates into a number
density of 1.2 x 10(-10) m(-3). The meteoroid cloud would be the product of
the whole dust trail and not only the part that was crossed in 1998.
Copyright ) 2000 Institute for Scientific Information
Addresses:
Nakamura R, Kobe Univ, Informat Proc Ctr, Kobe, Hyogo 6578501, Japan.
Kobe Univ, Informat Proc Ctr, Kobe, Hyogo 6578501, Japan.
Kobe Univ, Grad Sch Sci & Technol, Kobe, Hyogo 6578501, Japan.
Univ Tokyo, Grad Sch Sci, Tokyo 1138654, Japan.
NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA.
=================================================================
(4) METEORS, METEORITES & COSMIC DUST
F.J.M. Rietmeijer: Interrelationships among meteoric metals, meteors,
interplanetary dust, micrometeorites, and meteorites. METEORITICS &
PLANETARY SCIENCE 35: (5) 1025-1041 SEP 2000
Meteor science, aeronomy, and meteoritics are different disciplines with
natural interfaces. This paper is an effort to integrate the chemistry and
mineralogy of collected interplanetary dust particles (IDPs),
micrometeorites, and meteorites with meteoric data and with atmospheric
metal abundances. Evaporation, ablation, and melting of decelerating
materials in the Earth's atmosphere are the sources of the observed metal
abundances in the upper atmosphere. Many variables ultimately produce the
materials and phenomena we can analyze, such as different accretion and
parent-body histories of incoming extraterrestrial materials, different
interactions of meteors with the Earth's middle atmosphere, meteor data
reduction, and complex chemical interactions of the metals and ions with the
ambient atmosphere. The IDP-like and unequilibrated ordinary chondrite
matrix materials are reasonable sources for observed meteoric and
atmospheric metals. The hypothesis of hierarchical dust accretion predicts
that low, correlated refractory element abundances in cometary meteors may
be real. It implies that the CI or cosmic standard is not useful to
appreciate the chemistry of incoming petrologically heterogeneous cometary
matter. The quasi steady-state metal abundances in the lower thermosphere
and upper mesosphere are derived predominantly from materials with cometary
orbital characteristics and velocities such as comets proper and near-Earth
asteroids. The exact influence of atmospheric chemistry on these abundances
still needs further evaluation. Metal abundances in the lower mesosphere and
upper stratosphere region are mostly from materials from the asteroidal belt
and the Kuiper belt. Copyright ) 2000 Institute for Scientific Information
Addresses:
Rietmeijer FJM, Univ New Mexico, Dept Earth & Planetary Sci, Inst Meteorit,
Albuquerque, NM 87131 USA.
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at:
http://abob.libs.uga.edu/bobk/cccmenu.html
DISCLAIMER: The opinions, beliefs and viewpoints expressed in the
articles and texts and in other CCNet contributions do not
necessarily reflect the opinions, beliefs and viewpoints of
the moderator of this network.
------- End of Forwarded Message
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiac.net/users/lewkaren/meteorobs/subscribe.html