Astronomy Stories
Dr. John Mulchaey Staff Scientist Carnegie Observatories The light we see with our eyes only tells a small part of the Universe's story. To get a complete picture of how the Universe works,...
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Pasadena, CA— The Giant Magellan Telescope (GMT) has passed a major milestone as 11 international partners—including Carnegie—approved its construction, which secures the project...
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Pasadena, CA— Type Ia supernovae are violent stellar explosions that shine as some of the brightest objects in the universe. But there are still many mysteries surrounding their origin—...
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Type Ia supernovae are violent stellar explosions that shine as some of the brightest objects in the universe. But there are still many mysteries surrounding their origin—what kind of star...
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Two nights ago, for the first time in history, astronomers from University of Arizona and Carnegie's Yuri Beletsky at Las Campanas Observatory used the Clay Magellan telescope together with...
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Pasadena, CA- John Mulchaey has been appointed the new Crawford H. Greenewalt Director of the Carnegie Observatories. He is the eleventh director of the historic department, which was founded in 1904...
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Carnegie's John Mulchaey talks to NPR's Morning Edition about Edwin Hubble's work at the Mount Wilson Obeservatory and his famous Andromeda plates....
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A Carnegie-based search of nearby galaxies for their oldest stars has uncovered two stars in the Sculptor dwarf galaxy that were born shortly after the galaxy formed, approximately 13 billion years...
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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 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. 
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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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With the proliferation of discoveries of planets orbiting other stars, the race is on to find habitable worlds akin to the Earth. At present, however, extrasolar planets less massive than Saturn cannot be reliably detected. Astrophysicist John Chambers models the dynamics of these newly found giant...
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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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Stephen Shectman blends his celestial interests with his gift of developing novel telescope instrumentation. He investigates the large-scale structure of the galaxy distribution; searches for ancient stars that have few elements; develops astronomical instruments; and constructs large telescopes....
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It is commonly believed that when looking for valuable treasure, the best place to look is the attic—after all, works by Caravaggio, Van Gogh, Rembrandt, and Jackson Pollack have been...
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Quasars are supermassive black holes that sit at the center of enormous galaxies, accreting matter. They shine so brightly that they are often referred to as beacons and are among the most-distant...
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Astronomers with the Sloan Digital Sky Survey (SDSS), including Carnegie's Johanna Teske, have learned that the chemical composition of a star can exert unexpected influence on its...
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Decker French
July 24, 2019

Pasadena, CA— Carnegie’s K. Decker French was recognized by the Astronomical Society of the Pacific with its Robert J. Trumpler Award, which is presented to a recent Ph.D. graduate “whose research is considered unusually important to astronomy.” French completed her doctorate at the University of Arizona Tucson in 2017 and is currently a Hubble Fellow at the Carnegie Observatories.

Her research focuses on a radio survey of the gas clouds within galaxies that have recently ended the star-forming phase of their evolution.  The lack of star formation in these galaxies has long been assumed to be caused by a depletion of the cold, dense molecular gases

Vera measuring spectra with DTM measuring engine, courtesy of Carnegie Science.
July 24, 2019

Washington, DC—The House approved yesterday a bill to name the Large Synoptic Survey Telescope in honor of late Carnegie scientist Vera Rubin, who confirmed the existence of dark matter.

Rubin received the National Medal of Science for her research on how stars orbit their galactic centers. She revealed that stars at varying distances from the center of a spiral galaxy orbit at the same speed, rather than at decreasing speeds away from the center, providing undeniable evidence that each galaxy is embedded in a halo of dark matter holding its mass together.

She died in December 2016.

“Vera demonstrated intellectual courage and a tireless commitment to

An image of the Hubble Space Telescope floating against the background of space courtesy of NASA.
July 16, 2019

Pasadena, CA—A team of collaborators from Carnegie and the University of Chicago used red giant stars that were observed by the Hubble Space Telescope to make an entirely new measurement of how fast the universe is expanding, throwing their hats into the ring of a hotly contested debate. Their result—which falls squarely between the two previous, competing values—will be published in The Astrophysical Journal.

Nearly a century ago, Carnegie astronomer Edwin Hubble discovered that the universe has been growing continuously since it exploded into being during the Big Bang. But precisely how fast it’s moving—a value termed the Hubble constant in his

This cartoon courtesy of Anthony Piro illustrates three possibilities for the origin of the mysterious hydrogen emissions from the Type IA supernova called ASASSN-18tb that were observed by the Carnegie astronomers.
May 7, 2019

Pasadena, CA—Detection of a supernova with an unusual chemical signature by a team of astronomers led by Carnegie’s Juna Kollmeier—and including Carnegie’s Nidia Morrell, Anthony Piro, Mark Phillips, and Josh Simon—may hold the key to solving the longstanding mystery that is the source of these violent explosions. Observations taken by the Magellan telescopes at Carnegie’s Las Campanas Observatory in Chile were crucial to detecting the emission of hydrogen that makes this supernova, called ASASSN-18tb, so distinctive.   

Their work is published in Monthly Notices of the Royal Astronomical Society.

Type Ia supernovae play a

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The Carnegie-Spitzer-IMACS (CSI) survey, currently underway at the Magellan-Baade 6.5m telescope in Chile, has been specifically designed to characterize normal galaxies and their environments at a distance of about 4 billion years post Big Bang, expresses by astronomers as  z=1.5.

The survey selection is done using the Spitzer Space Telescope Legacy fields, which provides as close a selection by stellar mass as possible.

Using the IMACS infrared camera, the survey goal is to study galaxies down to low light magnitudes. The goal is to reduce the variance in the density of massive galaxies at these distances and times to accurately trace the evolution of the galaxy mass

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 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

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 earliest galaxies are those that are most distant. Staff associate Dan Kelson is interested in how these ancient relics evolved. The latest generation of telescopes and advanced spectrographs—instruments that analyze light to determine properties of celestial objects—allow astronomers to accurately measure enormous numbers of distant galaxies. Kelson uses the Magellan 6.5-meter telescopes and high-resolution imaging from the Hubble Space Telescope to study distant galaxies.His observations of their masses, sizes and morphologies allow him to directly measure their stars' aging to infer their formation history. Kelson is the principal investigator of the Carnegie-

Anthony Piro is the George Ellery Hale Distinguished Scholar in Theoretical Astrophysics at the Carnegie Observatories. He is a theoretical astrophysicist studying compact objects, astrophysical explosions, accretion flows, and stellar dynamics. His expertise is in nuclear physics, thermodynamics, condensed matter physics, General Relativity, and fluid and magneto-hydrodanmics. He uses this background  to predict new observational phenomena as well as to understand the key underlying physical mechanisms responsible for current observations. He uses a combination of analytic and simple numerical models to build physical intuition for complex phenomena.

Piro recieved his 

Like some other Carnegie astronomers, staff associate Jeffrey Crane blends science with technology. His primary interests are instrumentation, the Milky Way and the neighboring Local Group of galaxies, in addition to extrasolar planets. In 2004, then-research associate Crane joined Steve Shectman, Ian Thompson, and the Carnegie team to design the Planet Finder Spectrograph (PFS), now installed and operational on the Magellan Clay telescope.

Radial velocities are the speeds and directions of stars moving away from or toward the Earth.  Extrasolar planet hunters use them to detect the telltale wobbles of stars that are gravitationally tugged by orbiting planets. Astronomical

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 and during the formation of our Solar System. Meteorites are fragments of asteroids—small bodies that originated between Mars and Jupiter—and are likely the last remnants of objects that gave rise to the terrestrial planets. He is particularly interested in the analysis of chondrules, millimeter-size spherical objects that are the dominant constituent of the most primitive