Your search for ""Michel Mayor"" returned 18 results

Recent excitement about extrasolar planets exploded into controversy last year, when David Gray of the University of Western Ontario in Canada claimed that the first planet to be discovered outside of our solar system was not a planet at all. Michel Mayor and Didier Queloz of the Geneva Observatory in Switzerland suggested in 1995 that a planet was orbiting the Sun-like star Pegasi 51, an interpretation that Gray disputed. In the latest twist to the story. Gray has studied new data from the star and now that the planet does indeed exist.

Just over five years ago, astronomers had no evidence for planets circling Sun-like stars outside our solar system. This situation changed in 1995 when Michel Mayor and Didier Queloz at the Geneva Observatory discovered a massive planet orbiting just 7 million kilometres from its star. Now, planets are routinely detected around other Sun-like stars. Indeed, 30 extrasolar planets have been discovered so far, compared with just nine planets in our solar system.

James Peebles, Michel Mayor and Didier Queloz have been awarded the 2019 Nobel Prize for Physics for their contributions to cosmology and astronomy, as Michael Banks reports

We bring you, as usual, the Sun and Moon and stars, plus some galaxies and a new section on astrobiology. Some highlights are short (the newly identified class of gamma‐ray bursts, and the Deep Impact on Comet 9P/Tempel 1), some long (the age of the universe, which will be found to have the Earth at its center), and a few metonymic, for instance the term "down‐sizing" to describe the evolution of star formation rates with redshift.

We are undertaking an astrometric search for gas giant planets and brown dwarfs orbiting nearby low-mass dwarf stars with the 2.5 m du Pont Telescope at the Las Campanas Observatory in Chile. We have built two specialized astrometric cameras, the Carnegie Astrometric Planet Search Cameras (CAPSCam-S and CAPSCam-N), using two Teledyne HAWAII-2RG HyViSI arrays, with the cameras' design having been optimized for high-accuracy astrometry of M dwarf stars. We describe two independent CAPSCam data reduction approaches and present a detailed analysis of the observations to date of one of our target stars, NLTT 48256. Observations of NLTT 48256 taken since 2007 July with CAPSCam-S imply that astrometric accuracies of around 0.3 mas hr^-1 are achievable, sufficient to detect a Jupiter-mass companion orbiting 1 AU from a late M dwarf 10 pc away with a signal-to-noise ratio (S/N) of about 4. We plan to follow about 100 nearby (primarily within about 10 pc) low-mass stars, principally late M, L, and T dwarfs, for 10 yr or more, in order to detect very low-mass companions with orbital periods long enough to permit the existence of habitable, Earth-like planets on shorter-period orbits. These stars are generally too faint and red to be included in ground-based Doppler planet surveys, which are often optimized for FGK dwarfs. The smaller masses of late M dwarfs also yield correspondingly larger astrometric signals for a given mass planet. Our search will help to determine whether gas giant planets form primarily by core accretion or by disk instability around late M dwarf stars.

Existing exoplanet radial velocity surveys are complete in the planetary mass–semimajor axis (M_p–a) plane over the range 0.1 AU <a< 2.0 AU where M_p ≳ 100 M_⊕. We marginalize over mass in this complete domain of parameter space, and demonstrate that the observed a distribution is inconsistent with models of planet formation that use the full Type I migration rate derived from a linear theory and that do not include the effect of the ice line on the disk surface density profile. However, the efficiency of Type I migration can be suppressed by both nonlinear feedback and the barriers introduced by local maxima in the disk pressure distribution, and we confirm that the synthesized M_p–a distribution is compatible with the observed data if we account for both retention of protoplanetary embryos near the ice line and an order-of-magnitude reduction in the efficiency of Type I migration. The validity of these assumptions can be checked because they also predict a population of short-period rocky planets with a range of masses comparable to that of the Earth as well as a "desert" in the M_p–a distribution centered around M_p ∼ 30 − 50 M_⊕ and a < 1 AU. We show that the expected "desert" in the M_p–a plane will be discernible by a radial velocity survey with 1 m s⁻¹ precision and n ∼ 700 radial velocity observations of program stars.

The characterization of exoplanets and their birth protoplanetary disks has enormously advanced in the last decade. Benefitting from that, our global understanding of the planet formation processes has been substantially improved. In this review, we first summarize the cutting-edge states of the exoplanet and disk observations. We further present a comprehensive panoptic view of modern core accretion planet formation scenarios, including dust growth and radial drift, planetesimal formation by the streaming instability, core growth by planetesimal accretion and pebble accretion. We discuss the key concepts and physical processes in each growth stage and elaborate on the connections between theoretical studies and observational revelations. Finally, we point out the critical questions and future directions of planet formation studies.

In this autobiography of 70+ yr of publishing astronomical papers, I summarize some of my major fields of research, such as (1) hfs in the solar spectrum, (2) the atmospheres of supergiants, (3) shock waves in Cepheids, (4) the Crab Nebula, (5) frequencies of binaries, (6) exoplanets, (7) starting Kitt Peak National Observatory, (8) catalogs, (9) China, (10) editing the Astrophysical Journal, (11) blue stragglers, (12) the Local Interstellar Bubble, and (13) publication studies.

The last thirty years have seen an irrevocable change in the field of planetary science with the discovery of the first planets around stars other than our own Sun. While approximately twenty percent of the exoplanets we have discovered are close in size to the Earth, the similarity of their surface environment to our home world remains unknown. This book presents an exploration of the potential diversity of rocky planets through a quantitative study of how planetary processes change as properties deviate from the Earth. Changes in four specific properties are considered: the presence of a magnetic field, the production and loss of internal heat, planetary composition and volatile abundance.