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(meteorobs) Excerpts from "CCNet, 36/2000 - 21 March 2000"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet, 21 March 2000
Date: Tue, 21 Mar 2000 10:33:28 -0500 (EST)
CCNet, 36/2000 - 21 March 2000
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[...]
(5) VELOCITY OF LARGE COMETARY DUST PARTICLES
D.W. Hughes, UNIVERSITY OF SHEFFIELD
(6) CCD PHOTOMETRY OF ASTEROIDS 1982 TA & 1997 LY4
P. Pravec et al., ACADEMY OF SCIENCE OF THE CZECH REPUBLIC
[...]
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(5) VELOCITY OF LARGE COMETARY DUST PARTICLES
D.W. Hughes: On the velocity of large cometary dust particles.=20
PLANETARY AND SPACE SCIENCE, 2000, Vol.48, No.1, pp.1-7
*) UNIVERSITY OF SHEFFIELD,DEPT PHYS & ASTRON,SHEFFIELD S3 7RH,S=20
YORKSHIRE,ENGLAND
The Whipple formula for the emission velocity of meteoroid dust from
the surface of a cometary nucleus is reviewed and it is concluded that,
in normal circumstances, the dust velocity is 'low', typically being
less than 20% the radial gas velocity. If, however, the dust particle
contains some embedded snows when it leaves the cometary nucleus, its
final velocity is considerably increased. (C) 1999 Elsevier Science
Ltd. All rights reserved.
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(6) CCD PHOTOMETRY OF ASTEROIDS 1982 TA & 1997 LY4
P. Pravec*), L. Sarounova, M. Wolf, I.R.V. Ferrin, J. Zhu: CCD=20
photometry of asteroids (4197) 1982 TA and 1997 LY4. PLANETARY AND=20
SPACE SCIENCE, 2000, Vol.48, No.1, pp.59-65
*) ACADEMY OF SCIENCE OF THE CZECH REPUBLIC,INST ASTRON,CZ-25165=20
ONDREJOV,CZECH REPUBLIC
We present results of our photometric observations of the Apollo=20
asteroid (4197) 1982 TA and the Mars-crosser 1997 LY4. Their synodic=20
rotation periods (3.53802 +/- 0.00005) and (46.07 +/- 0.02) h,=20
respectively, have been derived. The fast rotation of (4197) suggests a =
lower limit of the bulk density of 1.1 g/cm(3). The mean diameter of=20
(4197) is likely in the range 3-6 km, The present knowledge does not=20
support a possibility that (4197) is an extinct cometary nucleus as=20
suggested from its orbit. The smaller (1.4-3 km), slowly-rotating=20
asteroid 1997 LY4 is an elongated object with the equatorial axis ratio =
greater than or equal to 1.8. (C) 1999 Elsevier Science Ltd. All rights =
reserved.
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