Tony Farnham's

Comet LINEAR (1999 S4) Research Page

Image of Comet LINEAR 1999 S4 on July 27, 2000

Comet LINEAR 1999 S4 was a dynamically new comet that disintegrated when it was near perihelion. Unlike comet Shoemaker-Levy 9, which was only discovered after it had broken up, comet LINEAR was observed by a number of astronomers around the time of breakup, and these observations provide a unique and exciting picture of the life and death of this comet.

Me and my collaborators

Tony Farnham (me) University of Texas at Austin (when the work was done)
David Schleicher Lowell Observatory
Laura Woodney Lowell Observatory
Peter Birch Perth Observatory
Clara Eberhardy University of Washington
Lorenza Levy Northern Arizona University

Importance of LINEAR 1999 S4

Normally, astronomers are only able to learn about comets by observing their exterior surface and the coma surrounding the nucleus. When we study a comet's coma (the gas and dust surrounding the nucleus) we are looking at material that has been lifted off the surface. Thus, we are only seeing a representative sample of the ices and dust that are inside. Only dust particles small enough to be lifted off the surface are respresented in the coma and only ices near the surface are vaporized.

Although a lot has been learned in this manner, the question always remains: "What is the inside of a comet like?"

LINEAR 1999 S4 is not the first comet to break up, (remember comet Shoemaker-Levy 9?) but it is unique among these in many respects:

For these reasons, it was possible to study this comet as we typically study comets, to characterize it in that manner. Observations from after the breakup then allowed us to see what the interior of the comet was like. A comparison of the pre- and post-breakup results provides a view of how the interior differs from what is inferred from coma measurements.

The following pages provide information about the studies of comet LINEAR that my collaborators and I have been working on. The results we obtained are related to those from other astronomers in an attempt to produce a coherent picture of comet LINEAR before and during its breakup.

Some of these results have been published in the 18 May 2001 issue of Science (Vol 292). A total of six reports about comet LINEAR were published in this issue.

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Last modified: May 18, 2001