Anat Shahar is pioneering a field that blends isotope geochemistry with high-pressure experiments to examine planetary cores and the Solar System’s formation, prior to planet formation, and how the planets formed and differentiated. Stable isotope geochemistry is the study of how physical and chemical processes can cause isotopes—atoms of an element with different numbers of neutrons-- to separate (called isotopic fractionation). Experimental petrology is a lab-based approach to increasing the pressure and temperature of materials to simulate conditions in the interior Earth or other planetary bodies.

Rocks and meteorites consist of isotopes that contain chemical fingerprints of long-gone eras. The lighter isotopes, with fewer neutrons, partially separate from heavier isotopes (fractionation). The different ratios of these isotopes can reveal the physical and chemical changes these materials have undergone.

Comparing seismic measurements and information on materials, researchers know that Earth’s outer core is not pure iron and nickel; something lighter is there. One candidate is silicon, the most abundant element in the crust. Shahar and her colleagues developed a way to test the silicon hypothesis. They developed lab techniques to define how isotopes of silicon and iron separate between metals characteristic of the core and silicate of the mantle under Earth-forming high pressures and temperatures. The results were compared with isotopes found in rocks on Earth and the most primitive meteorites called chondrites. Chondrites contain tiny grains of dust from the period when the Solar System began to coalesce. They found that the core could contain as much as 6% silicon by weight.   

Shahar received her B.S. and M. Eng. from Cornell University in geological engineering and geological sciences respectively. She received her Ph. D. in geochemistry from UCLA. Before becoming a staff scientist in 2009 she was a Carnegie postdoctoral fellow. For more see http://anatshahar.carnegiescience.edu

 

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Artist's conception of Farfarout. Credit: NOIRLab/NSF/AURA/J. da Silva.
February 10, 2021

Washington, DC—A team of astronomers, including Carnegie’s Scott Sheppard, David Tholen from the University of Hawaiʻi Institute for Astronomy, and Chad Trujillo from Northern Arizona University have discovered discovered the most distant object ever observed in our Solar System.

Officially called 2018 AG37, the object is nicknamed Farfarout for just how far away from the Sun it is orbiting—about 132 AU, where 1 AU is the distance between the Earth and Sun. At that distance, it takes an entire millennium to orbit the Sun.

The three colleagues have been surveying the sky since 2012 to map the Solar System beyond Pluto. FarFarOut joins a set of these

Illustration of lab-mimicry of exoplanet interiors by Carnegie's Katherine Cain/
February 9, 2021

Washington, DC— New research led by Carnegie’s Yingwei Fei provides a framework for understanding the interiors of super-Earths—rocky exoplanets between 1.5 and 2 times the size of our home planet—which is a prerequisite to assess their potential for habitability.  Planets of this size are among the most abundant in exoplanetary systems.  The paper is published in Nature Communications.

“Although observations of an exoplanet’s atmospheric composition will be the first way to search for signatures of life beyond Earth, many aspects of a planet’s surface habitability are influenced by what’s happening beneath the planet

Rough diamond photograph purchased from iStock
December 21, 2020

Washington, DC— A diamond lasts forever, but that doesn’t mean all diamonds have a common history. 

Some diamonds were formed billions of years ago in space as the carbon-rich atmospheres of dying stars expanded and cooled. In our own planet’s lifetime, high-temperatures and pressures in the mantle produced the diamonds that are familiar to us as gems. 5,000 years ago, a large meteorite that struck a carbon-rich sediment on Earth produced an impact diamond.

Each of these diamonds differs from the others in both composition and genesis, but all are categorized as “diamond” by the authoritative guide to minerals—the International

Islands of Four Mountains, Alaska. USGS Photo by John Lyons.
December 3, 2020

Washington, DC— A small group of volcanic islands in Alaska's Aleutian chain could actually be part of a single, previously unrecognized giant volcano in the same category as Yellowstone, according to work from a research team, including Carnegie’s Diana Roman, Lara Wagner, Hélène Le Mével, and Daniel Portner, as well as recently departed postdoc Helen Janiszewski (now at University of Hawaiʻi at Mānoa), who will present their findings at the American Geophysical Union’s Fall Meeting next week.

The Islands of the Four Mountains in the central Aleutians is a tight group of six volcanos: Carlisle, Cleveland, Herbert, Kagamil, Tana and

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Established in June of 2016 with a generous gift of $50,000 from Marilyn Fogel and Christopher Swarth, the Marilyn Fogel Endowed Fund for Internships will provide support for “very young budding scientists” who wish to “spend a summer getting their feet wet in research for the very first time.”  The income from this endowed fund will enable high school students and undergraduates to conduct mentored internships at Carnegie’s Geophysical Laboratory and Department of Terrestrial Magnetism in Washington, DC starting in the summer of 2017.

Marilyn Fogel’s thirty-three year career at Carnegie’s Geophysical Laboratory (1977-2013), followed

CALL FOR PROPOSALS

Following Andrew Carnegie’s founding encouragement of liberal discovery-driven research, the Carnegie Institution for Science offers its scientists a new resource for pursuing bold ideas.

Carnegie Science Venture grants are internal awards of up to $100,000 that are intended to foster entirely new directions of research by teams of scientists that ignore departmental boundaries. Up to six adventurous investigations may be funded each year. The period of the award is two

Andrew Steele joins the Rosetta team as a co-investigator working on the COSAC instrument aboard the Philae lander (Fred Goesmann Max Planck Institute - PI). On 12 November 2014 the Philae system will be deployed to land on the comet and begin operations. Before this, several analyses of the comet environment are scheduled from an approximate orbit of 10 km from the comet. The COSAC instrument is a Gas Chromatograph Mass Spectrometer that will measure the abundance of volatile gases and organic carbon compounds in the coma and solid samples of the comet.

The Anglo-Australian Planet Search (AAPS) is a long-term program being carried out on the 3.9-meter Anglo-Australian Telescope (AAT) to search for giant planets around more than 240 nearby Sun-like stars. The team, including Carnegie scientists,  uses the "Doppler wobble" technique to search for these otherwise invisible extra-solar planets, and achieve the highest long-term precision demonstrated by any Southern Hemisphere planet search.

Johanna Teske became the first new staff member to join Carnegie’s newly named Earth and Planets Laboratory (EPL) in Washington, D.C., on September 1, 2020. She has been a NASA Hubble Fellow at the Carnegie Observatories in Pasadena, CA, since 2018. From 2014 to 2017 she was the Carnegie Origins Postdoctoral Fellow—a joint position between Carnegie’s Department of Terrestrial Magnetism (now part of EPL) and the Carnegie Observatories.

Teske is interested in the diversity in exoplanet compositions and the origins of that diversity. She uses observations to estimate exoplanet interior and atmospheric compositions, and the chemical environments of their formation

Phillip Cleves’ Ph.D. research was on determining the genetic changes that drive morphological evolution. He used the emerging model organism, the stickleback fish, to map genetic changes that control skeletal evolution. Using new genetic mapping and reverse genetic tools developed during his Ph.D., Cleves identified regulatory changes in a protein called bone morphogenetic protein 6 that were responsible for an evolved increase in tooth number in stickleback. This work illustrated how molecular changes can generate morphological novelty in vertebrates.

Cleves returned to his passion for coral research in his postdoctoral work in John Pringles’ lab at Stanford

Brittany Belin joined the Department of Embryology staff in August 2020. Her Ph.D. research involved developing new tools for in vivo imaging of actin in cell nuclei. Actin is a major structural element in eukaryotic cells—cells with a nucleus and organelles —forming contractile polymers that drive muscle contraction, the migration of immune cells to  infection sites, and the movement of signals from one part of a cell to another. Using the tools developed in her Ph.D., Belin discovered a new role for actin in aiding the repair of DNA breaks in human cells caused by carcinogens, UV light, and other mutagens.

Belin changed course for her postdoctoral work, in

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