Dr. Janet Simpson

December 22, 2006

SETI Institute Principal Investigator

As the typical star evolves, its hydrogen burns, being converted to helium in a process that releases the energy we see as starlight. Astronomer Janet Simpson studies the steps that follow, asking questions like “How do heavy elements form and get spread around?” Once the hydrogen in the center of a star is all gone, the helium at the core of the star burns, leaving the heavy elements of carbon, nitrogen, and oxygen. In a star with the mass of the Sun, the center of the star shrinks while the outer layers expand, eventually leaving the star altogether as a nitrogen-enriched planetary nebula. In a much more massive star, the shrinkage of the center part of the star cannot be stopped: the star collapses and then rebounds into a brilliant supernova explosion, releasing its carbon, oxygen, and all the rest of its heavy elements into the galaxy. Among Simpson’s varied research projects, she examines the chemistry of galaxies and tries to understand whether the shocks given off by supernovas during their explosions might help to form a new generation of stars. “What makes stars form? What are the influences of massive stars on their environments?” Simpson asks. “When we can answer those questions,” she says, “we will have a greater understanding of how solar systems form, and ultimately, how life is created.”


- SETI Institute Explorer, Special Edition 2005