Georges Meylan | |
|---|---|
 Meylan | |
| Born | 31 July 1950 |
| Nationality | Swiss |
| Occupation | Astronomer |
Georges Meylan is a Swiss astronomer, born on July 31, 1950, in Lausanne, Switzerland. He was the director of the Laboratory of Astrophysics of the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and now a professor emeritus of astrophysics and cosmology at EPFL. He is still active in both research and teaching.
Georges Meylan was born on July 31, 1950., [1] in Lausanne, Switzerland, where he attended primary school. He then started his higher education with the Special Mathematics Course at the Swiss Federal Institute of Technology in Lausanne (Ecole Polytechnique Fédérale de Lausanne - EPFL), followed by a master of mathematical sciences, specializing in pure mathematics and fundamental research, at the University of Lausanne.
He then went to the University of Geneva for post-graduate studies in physics, where he obtained a master in astrophysics and astronomy. In the same institution, in 1985, he completed his PhD thesis devoted to the dynamical study of nearby stellar systems, called globular clusters, through the use of high-quality stellar radial velocities. [2] His PhD advisor was Michel Mayor (Nobel Prize in Physics in 2019).
Georges Meylan benefited from two postdoctoral positions, first, at the Astronomy Department of the University of California at Berkeley, CA, US, and, second, in the Scientific Group at the Headquarters of the European Southern Observatory in Munich, Germany. He then occupied positions as senior astronomer at the Space Telescope Science Institute, in Baltimore, MD, US and at the Headquarters of the European Southern Observatory in Munich, Germany. [3] From 1999 to 2012, he was a Visiting Associate in the Division of Physics, Mathematics, and Astronomy at the California Institute of Technology (Caltech) in Pasadena, CA, US.
From 2004 to 2015, Georges Meylan was a professor of Astrophysics and Cosmology at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and, simultaneously, the director of the EPFL Laboratory of Astrophysics. [4] Since September 2015, he is a professor emeritus at EPFL, still active in research and in teaching, both at EPFL and at the University of Lausanne.
Since the year of his PhD Thesis (1985), Georges Meylan has been asked to referee numerous papers submitted to the main astronomical journals (Nature, Astronomy & Astrophysics, Astrophysical Journal, Astronomical Journal, Monthly Notices of the RAS). He refereed numerous proposals from the National Science Foundation (NSF, US) and from the Swiss National Science Foundation (SNSF, Switzerland), among other similar national grant systems in Europe, US, and Asia. He was also a member of various refereeing processes, such as the Hubble Space Telescope Time allocation Committee (TAC) and the ESO Observing Programmes Committee (OPC). He organized about ten international conferences with the publications of their proceedings. He also organized a Saas Fee Course on gravitational lensing with the publication of the related book.
In addition, Georges Meylan was, in the framework of the International Astronomical Union (IAU), President of Commission 37 Star Clusters & Associations (2000-2003) and President of Division VII Galactic System (2000-2003), and then Advisor (2003-2006) to the same entities. He was president (2008-2015) of the Commission for Astronomy of the Swiss Academy of Sciences and was the scientific delegate for Switzerland on the ESO Council (2008-2014). During about the same period (2008-2016), he was a panel member and then panel chair in the framework for the European Research Council (ERC) in Brussels. From 2016 until 2022, he was a member of the Council of the European Astronomical Society (EAS). From 2016 to 2023, he chaired the Board of Trustees of the International Space Science Institute (ISSI) in Bern, Switzerland. He is a member of the Academia Europea.
Georges Meylan has contributed significantly to two main fields of research in astrophysics and cosmology. First, he studied the internal stellar kinematics and dynamics of globular clusters, [5] which are stellar systems containing from a few 105 to a few 106 stars. Second, he investigated the effect of gravitational lensing on distant galaxies and quasars induced by intervening galaxies and clusters of galaxies along the line of sight. Gravitational lensing is nowadays a genuine tool allowing the determination of some fundamental cosmological parameters, such as the Hubble constant H0 , related to the age of the Universe, and Ωm, and ΩΛ , which are, respectively, the fraction of matter (Baryonic and Dark Matter) and the fraction of Dark Energy in the Universe.
While at EPFL, he has initiated two long-term scientific programs. First, COSMOGRAIL [6] for the monitoring of light curves of the images of gravitationally lensed quasars, second, he involved Switzerland in the ESA satellite mission EUCLID, which will investigate the nature of Dark Energy and Dark Matter, the two main constituents of our Universe.
Here after are some highlights of his main research achievements, which have been published in more than 300 refereed papers :
A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".
Star clusters are large groups of stars held together by self-gravitation. Two main types of star clusters can be distinguished. Globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound. Open clusters are more loosely clustered groups of stars, generally containing fewer than a few hundred members, that are often very young. As they move through the galaxy, over time, open clusters become disrupted by the gravitational influence of giant molecular clouds. Even though they are no longer gravitationally bound, they will continue to move in broadly the same direction through space and are then known as stellar associations, sometimes referred to as moving groups.
Tucana is a constellation in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a 35-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the "Southern Birds".
The cosmic distance ladder is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances. Several methods rely on a standard candle, which is an astronomical object that has a known luminosity.
A stellar black hole is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be observed as a type of gamma ray burst. These black holes are also referred to as collapsars.
Abell 1835 IR1916 was a candidate for being the most distant galaxy ever observed, although that claim has not been verified by additional observations. It was claimed to lie behind the galaxy cluster Abell 1835, in the Virgo constellation.
OGLE-TR-122 is a binary stellar system containing one of the smallest main-sequence stars whose radius has been measured. It was discovered when the Optical Gravitational Lensing Experiment (OGLE) survey observed the smaller star eclipsing the larger primary. The orbital period is approximately 7.3 days. The system's primary is thought to resemble the Sun.
NGC 1427 is a low-luminosity elliptical galaxy located approximately 71 million light-years away from Earth. It was discovered by John Frederick William Herschel on November 28, 1837. It is a member of the Fornax Cluster. The galaxy has a stellar mass of 7.9 × 1010M☉, and a total mass of 9.4 × 1010M☉. However, the mass of the dark matter halo surrounding the galaxy is around 4.3 × 1012M☉.
LBQS 1429-008 is a distant physical triple quasar located 10.5 billion light years away from Earth in the constellation of Virgo. It was discovered in 1989 by Paul Hewett and his colleagues from the Institute of Astronomy, Cambridge in England.
Stanislav George Djorgovski is an American scientist and scholar. He obtained his B.A. in astrophysics in 1979 at the University of Belgrade. After receiving his PhD in astronomy from U.C. Berkeley in 1985, he was a Harvard Junior Fellow until 1987 when he joined the faculty at the California Institute of Technology, where he is currently a professor of astronomy and data science.
NGC 6388 is a globular cluster of stars located in the southern constellation of Scorpius. The cluster was discovered by Scottish astronomer James Dunlop on May 13, 1826 using a 20 cm (9 in) reflector telescope. It was later determined to be a globular cluster by English astronomer John Herschel, who was able to resolve it into individual stars. NGC 6388 is located at a distance of approximately 35,600 light-years (10.90 kpc) from the Sun. Due to its apparent visual magnitude of +6.8, binoculars or a small telescope are required to view it.
NGC 121 is a globular cluster of stars in the southern constellation of Tucana. It is the oldest globular cluster in the Small Magellanic Cloud (SMC), which is a dwarf satellite galaxy of the Milky Way. This cluster was first discovered by English astronomer John Herschel on September 20, 1835. The compiler of the New General Catalogue, Danish astronomer John Louis Emil Dreyer, described this object as "pretty bright, pretty small, little extended, very gradually brighter middle". The cluster is located at a distance of around 200,000 light-years (60 kpc) from the Sun.
NGC 3311 is a super-giant elliptical galaxy located about 190 million light-years away in the constellation Hydra. The galaxy was discovered by astronomer John Herschel on March 30, 1835. NGC 3311 is the brightest member of the Hydra Cluster and forms a pair with NGC 3309 which along with NGC 3311, dominate the central region of the Hydra Cluster.
DS Tucanae is a binary star system 144 light years away in the constellation of Tucana. It has an apparent visual magnitude of 8.5, and is a RS Canum Venaticorum variable. The system is notable for being young as a member of the 45 Myr old Tucana-Horologium moving group and for the primary star hosting the confirmed exoplanet DS Tucanae Ab, discovered by THYME, using TESS.
NGC 1369 is a barred lenticular galaxy located 59 millon light years away in constellation of Eridanus. The galaxy was discovered by astronomer Julius Schmidt on January 19, 1865, and is a member of the Fornax Cluster. NGC 1369 is a host to a supermassive black hole with an estimated mass of 1.8 millon solar masses.
PKS 1830-211 is a gravitationally-lensed blazar in the southern constellation of Sagittarius, one of the most powerful such objects known. It has a high redshift (z) of 2.507, an indicator of its significant distance. This flat-spectrum radio quasar (FSRQ) is one of the brightest extraterrestrial radio sources. In visible light, identification of this object is hampered by the galactic plane and an M-type star that lies near the line of sight.
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