The size of meteoroid constituent grains Implications for interstellar meteoroids

R.L. Hawkes\ M.D. Campbellab, A.G. LeBlanca'c, L. Parker3, P. Brown\ J. Jonesb, S.P. Worden", R.R. Correll6, S.C. Woodwortha'f, A.A. Fisher3'®, P. Guralh, I.S. Murray3"', M. Connors^, T. Montaguek, D. Jewell1 and D.D. Babcockm aPhysics Department, Mount Allison University, Sackville, NB Canada. bPhysics and Astronomy Department, University of Western Ontario, London, ON Canada. °Astronomy and Physics Department, Saint Marys University, Halifax, NS Canada dUnited States Air Force, Pentagon, Washington, DC USA

'Headquarters United States Air Force Space Command and NASA, Washington, DC USA

Engineering Physics Department, McMaster University, Hamilton, ON Canada.

department of Physics and Astronomy, University of Calgary, Calgary, AB Canada.

hScience Applications International Corporation, Arlington, VA USA.

'Department of Physics, University of Regina, Regina, SK Canada.

department of Physics, Athabasca University, Athabasca, AB Canada.

kAir Force Research Lab, Kirtland AFB, NM USA.

'United States Space Command, Colorado Springs, CO USA.

mCentre for Research in Earth and Space Science, York University, Toronto, ON Canada.

The most widely accepted model for the structure of cometary meteoroids is a dustball with grains bound together by a more volatile substance [1], In this paper we estimate the size distribution of dustball grains from meteor flare duration, using image intensified CCD records of 1998 Leonid meteors. Upon the assumption of simultaneous release of dustball grains at the beginning of the flare, numerical atmospheric ablation models suggest that the dustball grains in these Leonids are of the order of 10"5 to 10"4 kg, which is somewhat larger than estimates obtained by other methods. If the dustball grain sizes determined here are representative of cometary meteoroid structure in general, only the most massive (O and BO) type stars could eject these grains into interstellar space by radiation pressure forces.

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