Tech & Science
Technology and Science news from Boulder, Colorado
Mini quakes to shimmy the Rio Grand rift
Jan 11th
IN COLORADO AND NEW MEXICO, NEW STUDY SAYS
The Rio Grande Rift, a thinning and stretching of Earth’s surface that extends from Colorado’s central Rocky Mountains to Mexico, is not dead but geologically alive and active, according to a new study involving scientists from the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences.
“We don’t expect to see a lot of earthquakes, or big ones, but we will have some earthquakes,” said CU-Boulder geological sciences Professor Anne Sheehan, also a fellow at CIRES. The study also involved collaborators from the University of New Mexico, New Mexico Tech, Utah State University and the Boulder-headquartered UNAVCO. The Rio Grande Rift follows the path of the Rio Grande River from central Colorado roughly to El Paso before turning southeast toward the Gulf of Mexico.
Sheehan was not too surprised when a 5.3 magnitude earthquake struck about 9 miles west of Trinidad, Colo., in the vicinity of the Rio Grande Rift on Aug. 23, 2011. The quake was the largest in Colorado since 1967 and was felt from Fort Collins to Garden City, Kan.
Along the rift, spreading motion in the crust has led to the rise of magma — the molten rock material under Earth’s crust — to the surface, creating long, fault-bounded basins that are susceptible to earthquakes, said Sheehan, a study co-author and also associate director of the CIRES Solid Earth Sciences Division. The team studied the Rio Grande Rift region to assess the potential earthquake hazards.
Using Global Positioning System instruments at 25 sites in Colorado and New Mexico, the team tracked the rift’s miniscule movements from 2006 to 2011. “Questions we wanted to answer are whether the Rio Grande Rift is alive or dead, how is it deforming and whether it is opening or not,” said Sheehan.
The high-precision instrumentation has provided unprecedented data about the volcanic activity in the region. Previously, geologists had estimated the rift had spread apart by up to 2 inches or 5 millimeters each year, although the errors introduced by the scientific instruments were known to be significant. “The GPS used in this study has reduced the uncertainty dramatically,” Sheehan said.
Using the latest high-tech instrumentation, the scientists found an average strain rate of 1.2 “nanostrain” each year across the experimental area, the equivalent of about one-twentieth of an inch, or 1.2 millimeters, over a length of about 600 miles. “The rate is lower than we thought but it does exist,” Sheehan said.
The researchers also found the extensional deformation, or stretching, is not concentrated in a narrow zone centered on the Rio Grande Rift but is distributed broadly from the western edge of the Colorado Plateau well into the western Great Plains. “The surprising thing to come out of the study was that the strain was so spread out,” Sheehan said.
Results of the study are published in the January edition of the journal Geology.
The team plans to continue monitoring the Rio Grande Rift, probing whether the activity remains constant over time, said lead study author Henry Berglund of UNAVCO, who was a graduate student at CU-Boulder working at CIRES when he completed this portion of the research. Also, the team may attempt to determine vertical as well as horizontal activity in the region to tell whether the Rocky Mountains are still uplifting or not, Berglund said.
“Present-day measurements of deformation within continental interiors have been difficult to capture due to the typically slow rates of deformation within them,” Berglund said. “Now with the recent advances in space geodesy we are finding some very surprising results in these previously unresolved areas.”
As far as the potential for future earthquakes in the region, the study’s results are unequivocal, however. “The rift is still active,” Sheehan said.
The new study also is co-authored by CU-Boulder Associate Professor and CIRES Fellow Steven Nerem, Frederick Blume of UNAVCO, Anthony Lowry of Utah State University, Mousumi Roy of the University of New Mexico and Mark Murray of New Mexico Tech.
The National Science Foundation provided the funding for this study and the NSF-funded EarthScope program and UNAVCO provided instruments, equipment and engineering services. The Boulder-headquartered UNAVCO is a nonprofit, university-governed consortium that facilitates geosciences research and education.
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Young galaxies are 13-billion light years from home
Jan 10th
DEVELOPING GALAXY CLUSTER EVER FOUND
A team of researchers led by the University of Colorado Boulder has used NASA’s Hubble Space Telescope to uncover a cluster of galaxies in the initial stages of construction — the most distant such grouping ever observed in the early universe.
In a random sky survey made in near-infrared light, Hubble spied five small galaxies clustered together 13.1 billion light-years away. They are among the brightest galaxies at that epoch and very young, living just 600 million years after the universe’s birth in the Big Bang. One light-year is about 6 trillion miles.
Galaxy clusters are the largest structures in the universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster, or protocluster, presumably will grow into one of today’s massive galactic “cities” comparable to the nearby Virgo cluster, a collection of more than 2,000 galaxies.
The composite image at right, taken in visible and near-infrared light, reveals the location of five tiny galaxies clustered together 13.1 billion light-years away. The circles pinpoint the galaxies. The Wide Field Camera 3 aboard NASA’s Hubble Space Telescope spied the galaxies in a random sky survey. The developing cluster is the most distant ever observed. The young galaxies lived just 600 million years after the universe’s birth in the Big Bang. The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and Andromeda, and a few dozen small dwarf galaxies. The close-up images at right, taken in near-infrared light, show the puny galaxies. The letters “a” through “e” correspond to the galaxies’ location in the wide-field view at left. Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster’s M87. Galaxy clusters are the largest structures in the universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo cluster, a collection of more than 2,000 galaxies. Credit: NASA, ESA, M. Trenti (University of Colorado Boulder and Institute of Astronomy, University of Cambridge, U.K.), L. Bradley (Space Telescope Science Institute, Baltimore), and the BoRG team
or more information on the galaxies visit the news center at http://hubblesite.org/.
“These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together,” says the study’s leader, Michele Trenti, a research associate at CU-Boulder’s Center for Astrophysics and Space Astronomy and a newly appointed scientist at the Institute of Astronomy at the University of Cambridge in the United Kingdom. “The result confirms our theoretical understanding of the buildup of galaxy clusters. And Hubble is just powerful enough to find the first examples of them at this distance.”
Trenti will present his results Jan. 10 at the American Astronomical Society meeting in Austin, Texas. The study will appear in the Feb. 10 issue of The Astrophysical Journal.
Most galaxies in the universe live in groups and clusters, and astronomers have probed many mature “galactic cities” in detail as far as 11 billion light-years away. But finding clusters in the early phases of construction has been challenging because they are rare, dim and widely scattered across the sky.
“Records are always exciting, and this is the earliest and the most distant developing galaxy cluster that has ever been seen,” said CU-Boulder Professor Michael Shull of the astrophysical and planetary sciences department, a member of the observing team. “We have seen individual galaxies this old and far away, but we have not seen groups of them in the construction process before.”
Last year, a group of astronomers uncovered one distant developing cluster. Led by Peter L. Capak of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena, the astronomers discovered a galactic grouping 12.6 billion light-years away with a variety of telescopes, including Hubble. Spectroscopic observations were made with the W.M. Keck Observatory in Hawaii to confirm the cluster’s distance by measuring how much its light has been stretched by the expansion of space.
Trenti’s team used the sharp-eyed Wide Field Camera 3 to hunt for the elusive catch. “We need to look in many different areas because the odds of finding something this rare are very small,” Trenti said. “It’s like playing a game of Battleship: The search is hit and miss. Typically a region has nothing, but if we hit the right spot we can find multiple galaxies.”
Because these distant, fledgling clusters are so dim, the team hunted for the systems’ brightest galaxies. These bright lights act as billboards, advertising cluster construction zones, according to the team. Galaxies at early epochs don’t live alone. From simulations, the astronomers expect galaxies to be clustered together.
Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters. These powerful light beacons live in deep wells of dark matter, which form the underlying structure in which galaxy clusters form, Trenti said. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood.
The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed lots of gas through mergers with other galaxies, Trenti said. The team’s simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo Cluster’s M87.
The observations demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady but dramatic process of collision and agglomeration. Astronomers have likened the process to streams merging into tributaries, then into rivers and to a bay.
Hubble looked in near-infrared light because ultraviolet and visible light from distant objects have been stretched into near-infrared wavelengths by the expansion of space in these extremely distant galaxies. The observations are part of the Brightest of Reionizing Galaxies or BoRG survey, which is using Hubble’s Wide Field Camera 3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionization.
The team estimated the distance to the newly spied galaxies based on their colors, but the astronomers plan to follow up with spectroscopic observations to confirm their distance.
Without spectroscopic observations, it’s not clear whether the observed galaxies are gravitationally bound yet. The average distance between them is likely comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and Andromeda, and a few dozen small dwarf galaxies.
These observations are pushing Hubble to the limit of its ability. This region, however, will be prime country for future telescopes such as NASA’s James Webb Space Telescope, an infrared observatory scheduled to launch later this decade. Webb will see farther into the infrared, allowing it to hunt for even earlier stages of galaxy assembly within 300 million years of the Big Bang.
Shull, also a faculty member at CU-Boulder’s Center for Astrophysics and Space Astronomy, said the research team will receive an additional 260 orbits of observation time on Hubble to continue the search for more of the fledgling galaxy clusters as part of the BoRG survey. “There is high interest right now in learning if Earth is unique in the universe in its ability to host life,” he said. “Similarly, we are interested to see if these ancient, forming galaxy clusters we have identified are unique, or if there are others out there. I expect that we may find a few more.”
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute, or STScI, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc., in Washington, D.C.
For more information on the galaxies visit the news center at http://hubblesite.org/. For more information on CU-Boulder’s CASA visit http://casa.colorado.edu/.
For more information on CU-Boulder’s CASA visit http://casa.colorado.edu/.
Check out the NOOKS at Boulder Public Library soon
Jan 9th
Boulder Public Library begins checking out NOOK e-readers on Wednesday, Jan. 11. There are 12 NOOKs at the Main Library, and six each at the Meadows and George Reynolds branch libraries. The NOOKs are loaded with 31 bestseller titles, in fiction, non-fiction and biography categories.
Some of the bestseller titles include: Stephen King’s “11/22/63,” Garth Stein’s “The Art of Racing in the Rain,” Suzanne Collins’ Hunger Games trilogy, George R.R. Martin’s “A Game of Thrones,” Walter Isaacson’s biography of Steve Jobs, and Laura Hillenbrand’s “Unbroken.”
Patrons must be at least 18 years old and a Boulder city resident to check out a NOOK with their library card. NOOKs are available to be placed on hold now in the library’s catalog; visit boulderlibrary.org to place a hold by searching for “NOOK” or call 303-441-3100 for assistance.
“The library has been supporting reading and readers in Boulder for over 100 years,” said Reference and Collections Manager Melinda Mattingly. “New formats have come along in the past, but nothing like the e-book. It’s no surprise that Boulder library users of all ages are excited about e-books and e-readers at their library, and the library is very excited to offer them.”
The NOOKs check out for three weeks, and no renewals are possible. Overdue fees are $5 per day, and users are responsible for any loss or damage costs.
Boulder Public Library website: www.boulderlibrary.org