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Caltech Astronomer Receives 2017 Dan David Prize
News Writer: Whitney Clavin Shrinivas (Shri) KulkarniCredit: CaltechShrinivas (Shri) Kulkarni, the John D. and Catherine T. MacArthur Professor of Astronomy and Planetary Science and director of Caltech's Optical Observatories, has been awarded the 2017 Dan David Prize, along with the late Neil Gehrels (PhD '82) of NASA's Goddard Space Flight Center and Andrzej Udalski of the Warsaw University Astronomical Observatory.Each year, the Dan David Prize, endowed by the Dan David Foundation, awards three prizes worth $1 million each "for achievements having an outstanding scientific, technological, cultural or social impact on our world," according to the prize website. The awards are given in three fields within three "time dimensions"—past, present, and future.Kulkarni, Gehrels, and Udalski will split the prize for the future category. All three researchers work in the field of time-domain astronomy, in which varying astronomical objects or phenomena are studied over time."Much of recent astronomy has focused on the static sky. Over the past two decades, exploration of the dynamic sky—cosmic explosions, moving objects, variable stars—has blossomed and is now widely considered to be the next frontier," says Kulkarni.Born in India and now a U.S. citizen, Kulkarni joined Caltech in 1985. He is a leading authority on exotic astrophysical phenomena such as gamma ray bursts, brown dwarfs, and millisecond pulsars, and has been associated with many of the major advances in understanding the universe that have been made over the last decade. Kulkarni is the principal investigator behind the Palomar Transient Factory, a project that used a telescope at Caltech's Palomar Observatory to regularly scan the skies for variable and exploding stars, asteroids, comets, and other changing objects. He is also the principal investigator behind the PTF's successor, the Zwicky Transient Factory, which is scheduled to begin scanning the skies in July 2017.Gehrels, who passed away on February 6, 2017, earned his PhD from Caltech in 1982 under adviser Edward C. Stone, David Morrisroe Professor of Physics. Gehrels, a pioneer in the study of bursts of gamma rays from deep space, was principal investigator for NASA's Swift satellite. Swift and its predecessor, the Compton Gamma Ray Observatory, for which Gehrels served as the project scientist, helped reveal that many gamma ray bursts are likely caused by extremely energetic supernovas in distant galaxies.Udalski uses a technique called gravitational microlensing to look for dim objects, such as planets, that reveal themselves when they pass in front of other more distant stars and distort the starlight. He leads a microlensing project called the Optical Gravitational Lensing Experiment, or OGLE, which makes most of its observations at Las Campanas Observatory in Chile.
Neil Gehrels (PhD '82), 1952–2017
News Writer: Whitney Clavin Distinguished Alumni Award Recipient Neil Gehrels (PhD ’82, Physics)Neil Gehrels, a Caltech Distinguished Alumnus who earned his PhD in physics in 1982, passed away on February 6, 2017, at the age of 64.Gehrels, a friend and colleague to many scientists at Caltech, was a pioneer in the study of gamma-ray bursts, which are blasts of high-energy radiation that come from deep space. Based at NASA's Goddard Space Flight Center in Greenbelt, Maryland, Gehrels was the principal investigator for NASA's Swift Gamma-Ray Burst Mission, which has solved many mysteries about gamma-ray bursts. He was also the project scientist for NASA's upcoming Wide Field Infrared Survey Telescope (WFIRST), a large infrared-based space telescope that will search for planets beyond our sun as well as study the mysterious repulsive force in our universe dubbed dark energy. Additionally, Gehrels was a member of the LIGO Scientific Collaboration, the group that directly observed, for the first time, ripples in space and time called gravitational waves."Neil was a pioneering astronomer, a great instrumentalist, and the leader of astrophysics missions spanning from gamma rays to the infrared," says Fiona Harrison, the Benjamin M. Rosen Professor of Physics and the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy at Caltech. "He was also a mentor and friend to many, including myself. The entire astronomical community is mourning his loss."In a statement from Goddard, Chris Scolese, the center's director, said, "Our center has lost a dear friend and astronomy pioneer, and his spirit will always live on in our work. Those of us who were fortunate to work with Neil know of his unwavering enthusiasm for science and unselfish generosity in mentoring others."Gehrels' early passion was music. He played clarinet, guitar, and piano. As an undergraduate at the University of Arizona, he studied to be a classical-music composer. Later, he decided to add an undergraduate physics degree, and ultimately followed his newfound passion to Caltech. As a graduate student, Gehrels worked under physicists Robbie Vogt, the R. Stanton Avery Distinguished Service Professor and Professor of Physics, Emeritus; and Ed Stone, the David Morrisroe Professor of Physics and the project scientist for NASA's Voyager mission. One of Gehrels' first projects was to calibrate a cosmic-ray instrument on Voyager. Much later, in 2012, Voyager 1 entered the uncharted territory of interstellar space, where this instrument detected the full intensity of cosmic rays. In 1979, when the Voyager 1 and 2 spacecraft flew past Jupiter, Gehrels discovered speeding particles of oxygen and sulfur, the origins of which turned out to be volcanoes on Jupiter's moon Io. The discovery remains one of Gehrels most-cited papers and was the topic of his Caltech PhD.While at Caltech, Gehrels met his wife Ellen Williams (PhD '82), who serves as the director of the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) and as a professor of physics at the University of Maryland. Gehrels and Williams—who were both named as Caltech Distinguished Alumni in 2016—were married in Caltech's Dabney Gardens in 1980 and later moved to Maryland, where Gehrels began work at Goddard.It was at Goddard that Gehrels started studying highly energetic gamma rays that come from space. In the late 1980s, he developed balloon experiments to study gamma rays from the center of our Milky Way galaxy and from supernovas in other galaxies. From 1991 to 2000, he was the project scientist for the Compton Gamma-Ray Observatory, which began unraveling the mysteries of gamma-ray bursts. He served as the principal investigator for Swift, the successor of Compton, from 1999 until his death. Swift revealed that gamma-ray bursts likely come from tremendous supernova explosions as well as collisions between neutron stars."Neil built great missions so that astronomers like us can make discoveries about our universe," says Shrinivas (Shri) Kulkarni, the John
Hubble sees spiral in Andromeda
The Andromeda constellation is one of the 88 modern constellations and should not be confused with our neighboring Andromeda Galaxy. The Andromeda constellation is home to the pictured galaxy known as NGC 7640.
Scientists estimate solar nebula's lifetime
Scientists have estimated the lifetime of the solar nebula -- a key stage during which much of the solar system evolution took shape. This new estimate suggests that the gas giants Jupiter and Saturn must have formed within the first 4 million years of the solar system's formation.
What drives universe's expansion?
Experiments with advanced technology could soon test an idea developed by Albert Einstein almost exactly a century ago, and settle a longstanding puzzle over what is driving the accelerated expansion of the universe.
Relive the SmallGEO launch preparations from test to liftoff on 28 January of ESA's new small telecom platform
Graduate Students Peer into Cosmic Web
News Writer: Lori Dajose The Keck Cosmic Web Imager under construction in a clean room at Caltech. The instrument is currently being installed on the Keck II telescope in Hawaii.Credit: CaltechSince first light in 1993, the twin Keck Telescopes at Hawaii's W. M. Keck Observatory have produced images of stars, nebulae, and massive galaxies in unprecedented detail. However, bright objects like these represent only a small fraction of the total mass in the universe. Most regular matter exists in faint, long filaments stretching between galaxies to form the cosmic web—a vast, dim structure.The Keck Cosmic Web Imager (KCWI), designed and built at Caltech, is a highly sensitive instrument capable of imaging the cosmic web with more precision than any other cosmic web imager. It is currently being installed onto the Keck II telescope.The goal of KCWI is to understand the origin of galaxies, in particular, the physics of how they form within the cosmic web. Two Caltech graduate students, Donal O'Sullivan (MS '15) and Prachi Parihar (MS '16), worked on the instrumentation and observational aspects of KCWI. We sat down with them to discuss what it's like to build a brand-new instrument and what they hope it will discover.What are your specific roles in the mission?Donal O'Sullivan: I work on both the instrumentation and observational sides of KCWI. Obviously we haven't observed with KCWI yet, but I've spent a lot of time with its less-sensitive prototype, the Palomar Cosmic Web Imager at Caltech's Palomar Observatory. I built a small but vital component of KCWI—the module that houses the arc lamps used to spectrally calibrate the instrument—and helped the engineering team run data analysis to verify its performance.Prachi Parihar: I have helped with the instrumentation side of KCWI and have observed with its prototype at Palomar, but my main research work is on the theoretical side. KCWI is a complex instrument and one of the very few of its kind. We are observing parts of the cosmic web that have until now been invisible to astronomers. Given the uniqueness of these observations, it is critical that we understand how to analyze and interpret them. Simulations can be very helpful in this area because we can compare them with observational predictions for the same galaxies, providing both more guidance and confidence in our interpretation of the data.What kinds of challenges have you faced during this process?DO: One of the biggest challenges I think I faced was learning that "good enough" is "good enough." I think a lot of scientifically minded people have a natural desire to find the optimal solution to every problem, but there are some tasks where optimizing the solution becomes a big time-sink that costs more than it is worth. Identifying how good you really need a solution to be and taking the most time-effective approach instead is a really valuable skill.What discoveries are you looking forward to?DO: I am most excited about the potential to discover more examples of the protogalactic disks my adviser, Chris Martin [professor of physics], discovered with the Palomar Cosmic Web Imager. Currently, we believe that galaxies form when the dark matter in the universe gravitationally collapses to form dense regions that we call dark matter halos. These halos gravitationally pull "normal"—not dark—matter like hydrogen toward their centers. This gas spirals inward and forms a disk at the center due to the conservation of angular momentum, which eventually leads to disk galaxies like the Milky Way and Andromeda. Among other things, we are trying to image this happening in the early universe.PP: KCWI will go deeper and collect higher-quality data for more galaxies. So far, we have detected interesting structures ranging from large gaseous disks to clumps of gas. Each observation is unique, and each galaxy environment is different. I am looking forward to getting a larger statistical sample so we can determine the prevalence of different kinds of objects and piece together a more complete picture of galaxy environments
Hubble Sees Spiral in Andromeda
The Andromeda constellation is one of the 88 modern constellations and should not be confused with our neighboring Andromeda Galaxy.
Space, Science, and Technology Take Center Stage
The Science Line—a non-profit working to bridge the gap between science, technology and fashion by inspiring youth through STEM fashion shows, competitions, educational kits and hands-on workshops—hosted the first STEM Fashion Show in partnership with the Challenger Space Center of Arizona.
Our Solar System May Have Formed in 4 Million Years
Scientists from MIT and their colleagues have estimated the lifetime of the solar nebula -- a key stage during which much of the solar system evolution took shape....