Michel Mayor website

Among his recent projects, Malcolm Curtis edited and wrote articles for a University of Geneva website dedicated to one of its top professors, globally-renowned astrophysicist Michel Mayor. Here is one of the articles from Michel.Mayor.ch website:

Mayor’s Exoplanet Discovery Transforms Astronomy

September 27, 2011

By Malcolm Curtis

The announcement struck the world of astronomy like a thunderbolt. On October 6, 1995, Geneva-based astrophysicist Michel Mayor told a conference of scientists in Florence, Italy about a discovery that was to revolutionize the study of celestial objects.

For the first time, Professor Mayor and Didier Queloz, a PhD student at the University of Geneva, had identified a planet orbiting around a sun-like star outside the Solar System. The extrasolar planet, officially named 51 Pegasi b, is 50 light-years from Earth in the constellation of Pegasus. The find triggered an extraordinary new era in exoplanetary research.

The pair of scientists discovered the “exoplanet” through the use of the ELODIE spectrograph, a sophisticated instrument Mayor helped develop. It was attached to the 1.9-meter telescope at the Observatoire de Haute-Provence in southern France in 1994 and rapidly proved its worth. The device is designed to quantify with precision the velocity of a star whose position changes as the result of the gravitational pull of one or more orbiting planets.

This “radial velocity method” of identifying exoplanets, mastered by Mayor, measures the tiny wobbles caused by a planet’s gravitational interaction with a star. Planets are thus detected indirectly through a high-tech system involving fiber-optic cables feeding light from a telescope. Mayor and Queloz spent night after night studying 140 stars similar to our sun before finding 51 Pegasi b.

Even then, Mayor admits that he initially had doubts about the information first gathered from ELODIE about the exoplanet in late 1994. And other scientists adamantly dismissed these kind of instruments as being inadequate for hunting such planets.

“It was a new instrument so I was not completely sure,” the Swiss scientist recalled in an interview at his office at the Geneva Observatory. “At first we had very few measurements.” It was only after Mayor received more data that he felt confident enough to believe in the discovery.

Less than a week after Mayor and Queloz announced finding the exoplanet, the find was confirmed by scientists in America. Geoffrey Marcy from San Francisco State University and Paul Butler from the University of California, Berkeley, verified the exoplanet using another spectrograph at the Lick Observatory in California.

One of the revelations of the Swiss discovery was that a giant planet could revolve around sun-like stars with relatively short orbits. The exoplanet 51 Pegasi b, about 150 times the size of Earth and half the size of Jupiter, orbits around its star every four days and has a surface temperature believed to be more than 1,000 degrees Celsius.

Its identification triggered a tidal change in the knowledge of astrophysics about the universe. Students of astronomy were previously taught that only nine planets were known – all of them in the solar system.

The existence of other planets was theorized, but Mayor was the first to discover an exoplanet in orbit. He has subsequently gone on to find dozens of other exoplanets, including much smaller ones, closer to Earth’s mass, within habitable zones, where liquid water oceans could exist.

Following Mayor’s pioneering advances, other astronomers were encouraged to make radial velocity searches for planets in the neighbourhood of the sun. At last count, more than 680 exoplanets had been identified.

The Swiss astronomer and his team are pursuing their hunt for exoplanets with ever more sophisticated equipment. For the past several years, his research team has used a high-precision instrument called the High Accuracy Radial velocity Planet Searcher (HARPS).

The second-generation, high-precision spectograph was initially installed at the European Southern Observatory’s La Silla Observatory in Chile in 2003. With funding from ESO, the Swiss National Science Foundation and other Swiss and French government sources, the instrument was built by a group of partners, including the Geneva Observatory and the University of Bern.

Mayor is the principal investigator on HARPS, which is capable of detecting movements by stars of as little as 3.5 kilometres an hour. His team has used the instrument to identify the Gliese 581 solar system, home to the lightest known exoplanet orbiting a normal star with mass about twice that of Earth.


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