Stéphane Udry (born 1961 in

Sion, Switzerland , neighboring_municipalities= Ayent, Conthey, Grimisuat, Grône, Les Agettes, Nax, Nendaz, Saint-Léonard, Salins, Savièse, Vernamiège, Vex , twintowns = Sion (; german: Sitten ; it, Seduno; la, Sedunum) is a Swiss town, a mun ...

) is an

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

at the

Geneva Observatory The Geneva Observatory (french: Observatoire de Genève, german: Observatorium von Genf) is an astronomical observatory at Sauverny (CH) in the municipality of Versoix, Canton of Geneva, in Switzerland. It shares its buildings with the astronomy ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

, whose current work is primarily the search for

extra-solar planets An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

. He and his team, in 2007, discovered a possibly

terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Ve ...

in the

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kas ...

of the

Gliese 581 planetary system Gliese 581 () is a red dwarf star of spectral type M3V at the center of the Gliese 581 planetary system, about 20 light years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is t ...

, approximately 20

light years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

away in the constellation

Libra Libra generally refers to: * Libra (constellation), a constellation * Libra (astrology), an astrological sign based on the star constellation Libra may also refer to: Arts and entertainment * ''Libra'' (novel), a 1988 novel by Don DeLillo Musi ...

. He also led the observational team that discovered

HD 85512 b HD 85512 b is an exoplanet orbiting HD 85512, a K-type main-sequence star approximately 37 light-years from Earth in the constellation of Vela. Due to its mass of at least 3.6 times the mass of Earth, HD 85512 b is classified as a rocky Earth ...

, another most promisingly habitable exoplanet.

Career

Udry earned a doctorate at the

University of Geneva The University of Geneva (French: ''Université de Genève'') is a public research university located in Geneva, Switzerland. It was founded in 1559 by John Calvin as a theological seminary. It remained focused on theology until the 17th centu ...

in 1992, and spent two years at

Rutgers University Rutgers University (; RU), officially Rutgers, The State University of New Jersey, is a Public university, public land-grant research university consisting of four campuses in New Jersey. Chartered in 1766, Rutgers was originally called Queen's ...

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

. Later, Udry returned to Geneva, and worked with

Michel Mayor Michel Gustave Édouard Mayor (; born 12 January 1942) is a Swiss astrophysicist and professor emeritus at the University of Geneva's Department of Astronomy. He formally retired in 2007, but remains active as a researcher at the Observatory ...

, the discoverer of

51 Pegasi b 51 Pegasi b, officially named Dimidium , and formerly unofficially dubbed Bellerophon , is an extrasolar planet approximately away in the constellation of Pegasus. It was the first exoplanet to be discovered orbiting a main-sequence star, the S ...

, the first extrasolar planet found revolving around a

normal star In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

. In 2007, Udry was appointed full professor in the faculty of natural sciences at the University of Geneva.

Research

Udry's initial research concerned the dynamics of galaxies. His current work chiefly concerns the search for

by analyzing variations in the

radial velocities The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of stars. Among them was

Gliese 581c Gliese 581c (Gl 581c or GJ 581c) is a planet orbiting within the Gliese 581 system. It is the second planet discovered in the system and the third in order from the star. With a mass at least 5.5 times that of the Earth, it is classified as a s ...

(announced April 25, 2007) which at the time, was the most likely candidate for

habitability Habitability refers to the adequacy of an environment for human living. Where housing is concerned, there are generally local ordinances which define habitability. If a residence complies with those laws it is said to be habitable. In extreme e ...

of any extrasolar planet discovered so far. The planet was discovered by analyzing data obtained by the

High Accuracy Radial Velocity Planet Searcher The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. H ...

(HARPS) on the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...

's 3.6 meter telescope at

La Silla Observatory La Silla Observatory is an astronomy, astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are located at the site and are partly maintained by ESO. The obse ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. He was interviewed by

Mat Kaplan Mat Kaplan is an American radio personality. He is the former host of ''Planetary Radio'', a radio talk show about space exploration produced by The Planetary Society. Career Kaplan's extensive background in journalism has ranged from public ...

on ''Planetary Radio''. Udry described a new instrument known as the Echelle Spectrography for ''Rocky Exoplanet and Stable Spectroscopic Observations'', dubbed

ESPRESSO Espresso (, ) is a coffee-brewing method of Italian origin, in which a small amount of nearly boiling water (about ) is forced under of pressure through finely-ground coffee beans. Espresso can be made with a wide variety of coffee beans and ...

, might allow astronomers to detect Earth-like planets within five to ten years from 2010. An upgraded HARPS, of which Udry lead the observational team, found evidence that

Gliese 581d Gliese 581d (often shortened to Gl 581d or GJ 581d) is a proposed extrasolar planet orbiting within the Gliese 581 system, approximately 20.4 light-years away in the Libra constellation. It is the third planet claimed in the system and (assumi ...

might be more habitable (rather than c or g), and also detected another promising candidate:

References

20th-century Swiss astronomers University of Geneva alumni Rutgers University faculty Academic staff of the University of Geneva Living people 1961 births Discoverers of exoplanets People from Sion, Switzerland 21st-century Swiss astronomers {{Europe-astronomer-stub

Career

Research

See also

References