HD 209458 - First Exoplanet Confirmation by Transit Method
Date: 9 Sep 1999

This first planetary transit discovery is very exciting in that it gives astronomers a wealth of new information about the properties and formation of other solar systems.


At the end of August, 1999, STARE Project Astronomers Dr. Tim Brown and David Charbonneau started observing the star HD 209458 on the advisement of Dr. David Latham of the Harvard-Smithsonian Center for Astrophysics. Latham inferred from his radial-velocity analysis of the motion of the star that a planetary companion was present and possibly orbiting in an edge-on orientation. When an orbit is aligned this way, the planet will pass between its star and the Earth (transit) once each orbit, causing a slight dimming of the star's light. After analyzing data collected by the STARE telescope, such a dimming was discovered occurring on the nights of September 9th and 16th. The times of these transits coincided exactly with the expected times predicted by the radial-velocity analysis.


Text and figure provided by STARE and Dr. David Charbonneau publication, Astrophysical Journal Letters, 23 November, 1999.

Credit: Astrophysical Journal Letters