Josh Simon uses observations of nearby galaxies to study problems related to dark matter, chemical evolution, star formation, and the process of galaxy evolution.

In one area he looks at peculiarly dark galaxies. Interestingly, some galaxies are so dark they glow with the light of just a few hundred Suns. Simon and colleagues have determined that a tiny, very dim galaxy orbiting the Milky Way, called Segue 1, is the darkest galaxy ever found and has the highest dark matter density ever found. His team has also laid to rest a debate about whether Segue 1 really is a galaxy or a globular cluster—a smaller group of stars that lacks dark matter. Their findings make Segue 1 a promising laboratory to study dark matter, particularly the possibility that dark matter could be seen for the first time via a detection of gamma rays emanating from colliding dark matter particles.

Dark matter is the mysterious nonluminous material that makes up about most of the universe.  Dark energy is a mysterious repulsive force. Together they make up  about 95% of the universe. The rest--all observable matter--adds up to less than 5% of the universe.  Nearby dwarf galaxies have the highest measured densities of dark matter, making them ideal for dark matter studies, but that proximity also has a downside. Star systems so close to the massive Milky Way are subject to the acceleration of their stars by our galaxy’s tidal forces, an effect that can mimic the presence of dark matter. The lack of bright stars in dim dwarfs also makes it difficult to measure the velocities of enough stars for sufficient certainty. Simon and company overcame these hurdles with a comprehensive program that measured and analyzed the speed and chemistry of 397 stars in the vicinity of Segue 1.

 A major difference between galaxies and globular clusters--spherical collections of stars that are gravitationally bound--is that the stars in galaxies contain widely varying amounts of iron and other heavy elements, while stars in clusters do not. The new observations revealed that some Segue 1 stars have 50 times less iron than others in the galaxy, demonstrating conclusively that Segue 1 cannot be a globular cluster.

In collaboration with astronomers, Simon also showed that the high speeds of the Segue 1 stars are not caused by invisible binary companion stars, firming up the estimates of the amount of dark matter in the galaxy. Ongoing observations with NASA’s Fermi Gamma-ray Space Telescope are searching for signals from Segue 1 and other dwarfs, which would provide astronomers with concrete proof that their dark matter theories are on the right track\

Simon received his B.S. in physics from Stanford University and his M.A. and Ph. D. in astrophysics from UC-Berkeley. He was a postdoctoral scholar at Caltech from 2005-2008 and  the Vera Rubin Fellow at Carnegie from  2008 to 2010. For more information see http://obs.carnegiescience.edu/users/jsimon

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Carnegie Science, Carnegie Institution, Carnegie Institution for Science, ASAS-SN
July 28, 2017

Pasadena, CA— Carnegie’s Benjamin Shappee is part of a team of scientists, including an Australian amateur astronomer, which discovered a new comet last week.

Called the All Sky Automated Survey for Supernovae (ASAS-SN), the international collaboration, which is headquartered at the Ohio State University, uses a network of eight 14-centimeter telescopes around the world to scan the visible sky every two or three nights looking for very bright supernovae.

But this time out they found something else—a comet. 

Jose Prieto, a former Carnegie postdoc now a professor at Universidad Diego Portales in Chile, was the first ASAS-SN team member to notice the bright, moving

Carnegie Science, Carnegie Institution, Carnegie Institution for Science,
July 20, 2017

"The Moon needs no introduction ... To the layman, not versed in astrophysics, the Moon is the most-conspicuous object in the night sky and the rival of all heavenly objects, even including the Sun itself" wrote Carnegie's F.E. Wright in a poetic 1935 paper about the challenges of studying the lunar surface, which was written when the idea of sending humans there was beyond the imagination.

Reporting on the work of a Committee on Study of the Surface Features of the Moon, Wright laid out the challenges of approaching lunar research using the standard techniques employed by geologists of the time—food for thought on the anniversary of the 1969 Moon landing.  

"The observer

Carnegie Science, Carnegie Institution for Science, Carnegie Institution, Max Planck Institute for Astronomy
May 24, 2017

Pasadena, CA— A team of astronomers including Carnegie’s Eduardo Bañados and led by Roberto Decarli of the Max Planck Institute for Astronomy has discovered a new kind of galaxy which, although extremely old—formed less than a billion years after the Big Bang—creates stars more than a hundred times faster than our own Milky Way.

Their findings are published by Nature.

The team’s discovery could help solve a cosmic puzzle—a mysterious population of surprisingly massive galaxies from when the universe was only about 10 percent of its current age.

After first observing these galaxies a few years ago, astronomers proposed that they must have been created from hyper-

May 17, 2017

Former Carnegie fellow and current trustee, astronomer Sandra Faber, has been awarded the 2017 Gruber Foundation Cosmology Prize. She was awarded the lifetime achievement award for “her groundbreaking studies of the structure, dynamics, and evolution of galaxies.” Her work provided the impetus to study dark matter, the invisible material that makes up most of the mass of the universe, in addition to  “ the recognition that black holes reside at the heart of most large galaxies."

Faber also has a long history of contributing to  innovative telescope technology, and she has “aided and inspired the work of astronomers and cosmologists worldwide.”

The prize will be awarded this

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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 improved the

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 will

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/ccd/caps.

Guillermo Blanc wants to understand the processes by which galaxies form and evolve over the course of the history of the universe. He studies local galaxies in the “present day” universe as well as very distant and therefore older galaxies to observe the early epochs of galaxy evolution. Blanc conducts a series of research projects on the properties of young and distant galaxies, the large-scale structure of the universe, the nature of Dark Energy—the mysterious repulsive force, the process of star formation at galactic scales, and the measurement of chemical abundances in galaxies.

To conduct this work, he takes a multi-wavelength approach including observations in the UV,

Peter van Keken studies the thermal and chemical evolution of the Earth. In particularly he looks at the causes and consequences of plate tectonics; element modeling of mantle convection,  and the dynamics of subduction zones--locations where one tectonic plate slides under another. He also studies mantle plumes; the integration of geodynamics with seismology; geochemistry and mineral physics. He uses parallel computing and scientific visualization in this work.

He received his BS and Ph D from the University of Utrecht in The Netherlands. Prior to joining Carnegie he was on the faculty of the University of Michigan.

Peter Driscoll studies the evolution of Earth’s core and magnetic field including magnetic pole reversal. Over the last 20 million or so years, the north and south magnetic poles on Earth have reversed about every 200,000, to 300,000 years and is now long overdue. He also investigates the Earth’s inner core structure; core-mantle coupling; tectonic-volatile cycling; orbital migration—how Earth’s orbit moves—and tidal dissipation—the dissipation of tidal forces between two closely orbiting bodies. He is also interested in planetary interiors, dynamos, upper planetary atmospheres and exoplanets—planets orbiting other stars. He uses large-scale numerical simulations in much of his research

Andrew Newman works in several areas in extragalactic astronomy, including the distribution of dark matter--the mysterious, invisible  matter that makes up most of the universe--on galaxies, the evolution of the structure and dynamics of massive early galaxies including dwarf galaxies, ellipticals and cluster. He uses tools such as gravitational lensing, stellar dynamics, and stellar population synthesis from data gathered from the Magellan, Keck, Palomar, and Hubble telescopes.

Newman received his AB in physics and mathematics from the Washington University in St. Louis, and his MS and Ph D in astrophysics from Caltech. Before becomming a staff astronomer in 2015, he was a