Astronomy Stories
January 20, 2009 Speaker: Steven Beckwith Do you ever question the Big Bang? The Hubble Space Telescope has now looked far enough back in time to reveal the universe when it was very young and shows...
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January 17, 2008 Michael Brown  California Institute of Technology, Division of Geological and Planetary Sciences Pluto is no longer a planet. Did it really have it coming or are astronomers...
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The Carnegie Hubble program is an ongoing comprehensive effort that has a goal of determining the Hubble constant, the expansion rate of the universe,  to a systematic accuracy of 2%. As part of this program, astronomers are obtaining data at the 3.6 micron wavelength using the Infrared Array...
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The recent discovery that the universe is expanding at an accelerating rate has profoundly affected physics. If the universe were gravity-dominated then it should be decelerating. These contrary results suggest a new form of “dark energy”—some kind of repulsive force—is...
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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...
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While the planets in our Solar System are astonishingly diverse, all of them move around the Sun in approximately the same orbital plane, in the same direction, and primarily in circular orbits. Over the past 25 years Butler's work has focused on improving the measurement precision of stellar...
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Some 40 thousand tons of extraterrestrial material fall on Earth every year. This cosmic debris provides cosmochemist Conel Alexander with information about the formation of the Solar System, our galaxy, and perhaps the origin of life. Alexander studies meteorites to determine what went on before...
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Gwen Rudie
Gwen Rudie studies the chemical and physical properties of very distant galaxies and their surrounding gas in order to further our understanding of the processes that are central to the formation and development of galaxies. Critical to this research is our ability to trace the raw...
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Pasadena, CA— Supernovae were always thought to occur in two main varieties. But a team of astronomers including Carnegie’s Wendy Freedman, Mark Phillips and Eric Persson is reporting the discovery...
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Pasadena, CA—An international team of astronomers, including Carnegie’s Eric Persson, has charted the rise and fall of galaxies over 90 percent of cosmic history. Their work, which includes some of...
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Earth's Moon, public domain image
January 23, 2019

Pasadena, CA— “Can moons have moons?”

This simple question—asked by the four-year old son of Carnegie’s Juna Kollmeier—started it all.  Not long after this initial bedtime query,  Kollmeier was coordinating a program at the Kavli Institute for Theoretical Physics (KITP)  on the Milky Way while her one-time college classmate Sean Raymond of Université de Bordeaux was attending a parallel KITP program on the dynamics of Earth-like planets.   After discussing this very simple question at a seminar, the two joined forces to solve it.  Their findings are the basis of a paper published in Monthly Notices

December 14, 2018

Pasadena, CA— Miguel Roth, director of Carnegie’s Las Campanas Observatory in Chile from 1990 to 2014 and the current representative of the Giant Magellan Telescope Organization (GMTO) in Chile was awarded the Bernardo O’Higgins Order by the Chilean Foreign Affairs Ministry in Santiago today. The honor is in recognition “of his contribution to the development of astronomy in Chile, and for inspiring appreciation and knowledge of astronomy among students and people of all ages.”

The award is the highest civilian honor for non-Chileans. O’Higgins was one of the founders of the Chilean Republic. The award was established in 1965 to recognize

An artist’s conception of a type Ia supernova exploding, courtesy of ESO.
December 11, 2018

Pasadena, CA—New work from the Carnegie Supernova Project provides the best-yet calibrations for using type Ia supernovae to measure cosmic distances, which has implications for our understanding of how fast the universe is expanding and the role dark energy may play in driving this process. Led by Carnegie astronomer Chris Burns, the team’s findings are published in The Astrophysical Journal.  

Type Ia supernovae are fantastically bright stellar phenomena. They are violent explosions of a white dwarf—the crystalline remnant of a star that has exhausted its nuclear fuel—which is part of a binary system with another star.

In addition to being

Pan-STARRS image showing the host galaxy of the newly discovered supernova ASASSN-18bt
November 29, 2018

Pasadena, CA—A supernova discovered by an international group of astronomers including Carnegie’s Tom Holoien and Maria Drout, and led by University of Hawaii’s Ben Shappee, provides an unprecedented look at the first moments of a violent stellar explosion. The light from the explosion's first hours showed an unexpected pattern, which Carnegie's Anthony Piro analyzed to reveal that the genesis of these phenomena is even more mysterious than previously thought.

Their findings are published in a trio of papers in The Astrophysical Journal and The Astrophysical Journal Letters. (You can read them here, here, and here.)

Type Ia supernovae are

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The Carnegie Hubble program is an ongoing comprehensive effort that has a goal of determining the Hubble constant, the expansion rate of the universe,  to a systematic accuracy of 2%. As part of this program, astronomers are obtaining data at the 3.6 micron wavelength using the Infrared Array Camera (IRAC) on Spitzer Space Telescope. The team has demonstrated that the mid-infrared period-luminosity relation for Cepheids, variable stars used to determine distances and the rate of the expansion,  at 3.6 microns is the most accurate means of measuring Cepheid distances to date. At 3.6 microns, it is possible to minimize the known remaining systematic uncertainties in the Cepheid

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 recent discovery that the universe is expanding at an accelerating rate has profoundly affected physics. If the universe were gravity-dominated then it should be decelerating. These contrary results suggest a new form of “dark energy”—some kind of repulsive force—is driving the universe. To get a grasp of dark energy, it is extremely important that scientists get the most accurate measurements possible of Type Ia supernovae. These are specific types of exploring stars with exceptional luminosity that allow astronomers to determine distances and the acceleration rate at different distances. At the moment, the reality of the accelerating universe remains

The Carnegie Irvine Galaxy Survey is obtaining high-quality optical and near-infrared images of several hundred of the brightest galaxies in the southern hemisphere sky, at Carnegie’s Las Campanas Observatory to investigate the structural properties of galaxies. For more see    http://cgs.obs.carnegiescience.edu/CGS/Home.html

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

Staff astronomer emeritus Eric Persson headed a group that develops and uses telescope instrumentation to exploit new near-infrared (IR) imaging array detectors. The team built a wide-field survey camera for the du Pont 2.5-meter telescope at Carnegie’s Las Campanas Observatory in Chile, and the first of two cameras for the Magellan Baade telescope. Magellan consortium astronomers use the Baade camera for various IR-imaging projects, while his group focuses on distant galaxies and supernovae.

Until recently, it was difficult to find large numbers of galaxies at near-IR wavelengths. But significant advances in the size of IR detector arrays have allowed the Persson group

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

Looking far into space is looking back in time. Staff astronomer emeritus Alan Dressler began his career at Carnegie some years ago as a Carnegie Fellow. Today, he and colleagues use Magellan and the Hubble Space Telescope to study galaxy evolution—how galaxy structures and shapes change, the pace and character of star birth, and how large galaxies form from earlier, smaller systems.

Dressler is also intricately involved in instrumentation. He led the effort for the Inamori Magellan Areal Spectrogrph (IMACS), a wide-field imager and multi-object spectrograph which became operational in 2003 on the Baade telescope at Carnegie’s Las Campanas Observatory. Spectrographs