Chandra Release - July 27, 2000

Visual Description: Comet C/1999 S4

An astronomical image of Comet C/1999 S4 (LINEAR) is shown, which is a comet that was discovered in 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) project.  The image is dominated by orange and yellow colors.  The colors represent the intensity of the X-rays with white being the most intense, then yellow, orange, and red. The shape of the image is elongated, with a bright yellow-white patch in the center.   The details of the Chandra emission show that the X-rays are produced by collisions of ions racing away from the Sun with gas in the comet. In the collision the solar ion captures an electron from a cometary atom into a high energy state. The solar ion then kicks out an X-ray as the electron drops to a lower energy state.