Astronomers measure meteoroid tunnels diameter in atmosphere

A team of Japanese astronomers have successfully evaluated the diameters of heated tunnels left behind by meteoroids flashing through Earths atmosphere.

Washington, Sept 11 : A team of Japanese astronomers have successfully evaluated the diameters of heated tunnels left behind by meteoroids flashing through Earth's atmosphere.

When meteoroids flash through Earth's atmosphere, they bore tunnels through the air, leaving behind narrow meteor tracks that are heated by the collision of the fast-moving incoming object with atoms of highly diluted atmospheric gases.

The width of the tracks they make has long been known to be narrower than a metre, but until recently, more precise measurements have been impossible to make.

Now, researchers from the National Astronomical Observatory of Japan, the University of Tokyo, the Japan Aerospace Exploration Agency, the University of Electro-Communication, the RIKEN research institute, and Nagano National College of Technology have evaluated the diameters of these heated tunnels left behind by typical sporadic meteors penetrating the upper atmosphere, scattering atmospheric atoms and releasing photons of light.

The team compared the number of special photons produced as a meteoroid collided with the atmospheric atoms, and found a typical column width as narrow as a few millimetres across.

Observations on the Subaru telescope during a meteor shower on the nights of August 12-15, 2004 revealed a number of meteoroid tracks traversing the field of view of the camera.

During the 19 hour-long CCD exposures, the scientists recorded 55 tracks of which 13 were meteor tracks. Only one was from the radiant of the Perseid meteor shower and another was associated with the Aquarid meteor shower.

Most of the remaining meteor tracks were from sporadic meteoroids.

Scientists estimated the actual size of meteoroids in the current observation to be between 0.1 and 1 millimetre (derived from their luminosity).

Researchers say this is the first time the width of a meteor track column has been precisely measured using a physical analysis of the light emitted during an event (a meteoroid shower).

The results of this study were published in the August 25, 2007 issue of the Publications of the Astronomical Society of Japan.

ANI