Globular clusters are spherical systems of some 100,000  gravitationally bound stars. They are among the oldest components of our galaxy and are key to understanding the age and scale of the universe. Previous measurements of their distances have compared the characteristics of different types of stars in the solar neighborhood with the same types of stars found in the clusters. However, these measurements have systematic errors, which limit the determination of cluster ages and distances.

 Ian Thompson has a different approach to the problem: using observations of exceedingly rare Detached Eclipsing Binary stars. These systems have two separated stars orbiting each other such that the orbital plane is in the line of sight to the stars. As one star passes in front of the other the total light is modulated, and the shapes of these eclipses determine their relative sizes and separation. Variations in their radial velocities and Kepler's laws yield absolute dimensions of the system. Distances to the binaries can then be measured by comparing their apparent brightness with their surface brightness, as estimated from their infrared colors. The ages can be determined when one of the stars is at the end of its main-sequence lifetime.

Thompson searches for these stars by monitoring a sample of nearby southern globular clusters with the Swope 1-meter telescope at Carnegie’s Las Campanas Observatory over many nights to detect eclipses and measure the orbital periods. The shape of the light curves—the way the brightness varies over time--are measured with the du Pont 2.5-meter telescope, and radial velocity curves are now being obtained with the MIKE echelle spectrograph on the Clay telescope. Only one to four eclipsing binaries have been detected in each cluster, but these are sufficient to overhaul our imperfect knowledge of their distances and ages.

Thompson also works on instrumentation. With instrument scientist Greg Burley, he has built the CCD cameras for Magellan instrumentation (IMACS, MagE, MIKE, and LDSS3) and the guide cameras for the two Magellan telescopes. Other projects include a camera for the Magellan Planet Finding Spectrograph, and a novel astrometric camera for the du Pont telescope being built in collaboration with Alan Boss.

 Thompson received his B.Sc. and M. Sc. in physics and astronomy from the University of British Columbia and his Ph. D. from the University of Western Ontario where he was also a postdoctoral fellow. Before becoming a staff astronomer at Carnegie in in 1994 he was a staff associate, research associate and Carnegie fellow. For more information see http://obs.carnegiescience.edu/users/ian

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Fotografía de Yuri Beletsky, cortesía de la Carnegie Institution for Science.
April 27, 2020

Pasadena, California— El universo está lleno de miles de millones de galaxias—pero su distribución en el espacio está lejos de ser uniforme. ¿Por qué vemos tantas estructuras en el universo hoy y cómo se formó y creció todo?

Una encuesta de decenas de miles de galaxias, realizada durante 10 años utilizando el telescopio de Magallanes Baade perteneciente al Observatorio Las Campanas de Carnegie en Chile, proporcionó un enfoque para responder a este misterio fundamental. Los resultados, liderados por Daniel Kelson, de Carnegie, fueron publicados en Monthly Notices of the Royal Astronomical Society.

The Magellan telescopes at LCO by Yuri Beletsky.
April 27, 2020

Pasadena, CA— The universe is full of billions of galaxies—but their distribution across space is far from uniform. Why do we see so much structure in the universe today and how did it all form and grow? 

A 10-year survey of tens of thousands of galaxies made using the Magellan Baade Telescope at Carnegie’s Las Campanas Observatory in Chile provided a new approach to answering this fundamental mystery. The results, led by Carnegie’s Daniel Kelson, are published in Monthly Notices of the Royal Astronomical Society. 

“How do you describe the indescribable?” asks Kelson. “By taking an entirely new approach to the problem.

Caltech logo
March 17, 2020

The Carnegie Institution for Science is consolidating our California research departments into an expanded presence in Pasadena. With this move, we are building on our existing relationship with Caltech, with a goal of broadening our historic collaborations in astronomy and astrophysics and pursuing new opportunities in ecology and plant biology that will support the global fight against climate change.

This plan, which affects our research operations in Pasadena and Palo Alto, reflects Carnegie’s ongoing efforts to extend our leadership in space, Earth, and life sciences and to enhance our ability to explore new frontiers.

In selecting our Pasadena location, we

 Illustration of DS Tuc AB by M. Weiss, CfA.
March 9, 2020

Pasadena, CA— A new kind of astronomical observation helped reveal the possible evolutionary history of a baby Neptune-like exoplanet.

To study a very young planet called DS Tuc Ab, a Harvard & Smithsonian Center for Astrophysics-led team that included six Carnegie astronomers—Johanna Teske, Sharon Wang, Stephen Shectman, Paul Butler, Jeff Crane, and Ian Thompson—developed a new observational modeling tool. Their work will be published in The Astrophysical Journal Letters and represents the first time the orbital tilt of a planet younger than 45 million years—or about 1/100th the age of the Solar System—has been measured.

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The fund supports a postdoctoral fellowship in astronomy that rotates between the Carnegie Science departments of Terrestrial Magnetism in Washington, D.C., and the Observatories in Pasadena California. 

The Earthbound Planet Search Program has discovered hundreds of planets orbiting nearby stars using telescopes at Lick Observatory, Keck Observatory, the Anglo-Australian Observatory, Carnegie's Las Campanas Observatory, and the ESO Paranal Observatory.  Our multi-national team has been collecting data for 30 years, using the Precision Doppler technique.  Highlights of this program include the detection of five of the first six exoplanets, the first eccentric planet, the first multiple planet system, the first sub-Saturn mass planet, the first sub-Neptune mass planet, the first terrestrial mass planet, and the first transit planet.Over the course of 30 years we have

The Giant Magellan Telescope will be one member of the next class of super giant earth-based telescopes that promises to revolutionize our view and understanding of the universe. It will be constructed in the Las Campanas Observatory in Chile. Commissioning of the telescope is scheduled to begin in 2021.

The GMT has a unique design that offers several advantages. It is a segmented mirror telescope that employs seven of today’s largest stiff monolith mirrors as segments. Six off-axis 8.4 meter or 27-foot segments surround a central on-axis segment, forming a single optical surface 24.5 meters, or 80 feet, in diameter with a total collecting area of 368 square meters. The GMT

Along with Alycia Weinberger and Ian Thompson, Alan Boss has been running the Carnegie Astrometric Planet Search (CAPS) program, which searches for extrasolar planets by the astrometric method, where the planet's presence is detected indirectly through the wobble of the host star around the center of mass of the system. With over eight years of CAPSCam data, they are beginning to see likely true astrometric wobbles beginning to appear. The CAPSCam planet search effort is on the verge of yielding a harvest of astrometrically discovered planets, as well as accurate parallactic distances to many young stars and M dwarfs. For more see  http://instrumentation.obs.carnegiescience.edu/

Evolutionary geneticist Moises Exposito-Alonso joined the Department of Plant Biology as a staff associate in September 2019. He investigates whether and how plants will evolve to keep pace with climate change by conducting large-scale ecological and genome sequencing experiments. He also develops computational methods to derive fundamental principles of evolution, such as how fast natural populations acquire new mutations and how past climates shaped continental-scale biodiversity patterns. His goal is to use these first principles and computational approaches to forecast evolutionary outcomes of populations under climate change to anticipate potential future

Staff Associate Kamena Kostova joined the Department of Embryology in November 2018. She studies ribosomes, the factory-like structures inside cells that produce proteins. Scientists have known about ribosome structure, function, and biogenesis for some time. But, a major unanswered question is how cells monitor the integrity of the ribosome itself. Problems with ribosomes have been associated with diseases including neurodegeneration and cancer. The Kostova lab investigates the fundamental question of how cells respond when their ribosomes break down using mass spectrometry, functional genomics methods, and CRISPR genome editing.

Kostova received a B.S. in Biology from the

Sally June Tracy applies cutting-edge experimental and analytical techniques to understand the fundamental physical behavior of materials at extreme conditions. She uses dynamic compression techniques with high-flux X-ray sources to probe the structural changes and phase transitions in materials at conditions that mimic impacts and the interiors of terrestrial and exoplanets. She is also an expert in nuclear resonant scattering and synchrotron X-ray diffraction. She uses these techniques to understand novel behavior at the electronic level.  Tracy received her Ph.D. from the California Institute of

The Ludington lab investigates complex ecological dynamics from microbial community interactions using the fruit fly  Drosophila melanogaster. The fruit fly gut carries numerous microbial species, which can be cultured in the lab. The goal is to understand the gut ecology and how it relates to host health, among other questions, by taking advantage of the fast time-scale and ease of studying the fruit fly in controlled experiments.