Mansi Kasliwal, an assistant professor of astronomy at Caltech who studies stellar explosions and other cataclysmic events in the night sky, has been awarded a 2018 Packard Fellowship in Science and Engineering. The prestigious fellowships, awarded by the David and Lucile Packard Foundation, provide each fellow $875,000 over five years to pursue their research. The goal of the fellowships is to allow early-career professors to pursue science and engineering studies with few funding restrictions. "This gives me the freedom to dream big and try something adventurous," says Kasliwal (PhD '11).
Kasliwal plans to use the funding for two of her favorite projects—both wide-field infrared-sensing telescopes at Caltech's Palomar Observatory. The first telescope, called Palomar Gattini-IR, is already built and installed and began its observations in early September, while a second, bigger telescope called WINTER (Wide-field INfrared Transient ExploreR)is being developed now and will be installed at Palomar in two years. Both have the potential to discover new cosmic fireworks, such as supernovae that are hidden in dust and hard to see with optical light. The strength of infrared telescopes like Palomar Gattini-IR and WINTER is that they can see right through dusty, cold, or opaque explosions.
We sat down with Kasliwal to talk more about her telescope projects and what the Packard Fellowship means for her research.
Fiona Harrison, the division chair for physics, mathematics and astronomy, sat down with me for coffee at Caltech's Red Door Caf
A Caltech-led team of researchers has observed the peculiar death of a massive star that exploded in a surprisingly faint and rapidly fading supernova. These observations suggest that the star has an unseen companion, gravitationally siphoning away the star's mass to leave behind a stripped star that exploded in a quick supernova. The explosion is believed to have resulted in a dead neutron star orbiting around its dense and compact companion, suggesting that, for the first time, scientists have witnessed the birth of a compact neutron star binary system.
The research was led by graduate student Kishalay De and is described in a paper appearing in the October 12 issue of the journal Science. The work was done primarily in the laboratory of Mansi Kasliwal (MS '07, PhD '11), assistant professor of astronomy. Kasliwal is the principal investigator of the Caltech-led Global Relay of Observatories Watching Transients Happen (GROWTH) project.
When a massive star—at least eight times the mass of the sun—runs out of fuel to burn in its core, the core collapses inwards upon itself and then rebounds outward in a powerful explosion called a supernova. After the explosion, all of the star's outer layers have been blasted away, leaving behind a dense neutron star—about the size of a small city but containing more mass than the sun. A teaspoon of a neutron star would weigh as much as a mountain.
During a supernova, the dying star blasts away all of the material in its outer layers. Usually, this is a few times the mass of the sun. However, the event that Kasliwal and her colleagues observed, dubbed iPTF 14gqr, ejected matter only one fifth of the mass of the sun.
"We saw this massive star's core collapse, but we saw remarkably little mass ejected," Kasliwal says. "We call this an ultra-stripped envelope supernova and it has long been predicted that they exist. This is the first time we have convincingly seen core collapse of a massive star that is so devoid of matter."
The fact that the star exploded at all implies that it must have previously been enveloped in lots of material, or its core would never have become heavy enough to collapse. But where, then, was the missing mass?
The researchers inferred that the mass must have been stolen—the star must have some kind of dense, compact companion, either a white dwarf, neutron star, or black hole—close enough to gravitationally siphon away its mass before it exploded. The neutron star that was left behind from the supernova must have then been born into orbit with that dense companion. Observing iPTF 14gqr was actually observing the birth of a compact neutron star binary. Because this new neutron star and its companion are so close together, they will eventually merge in a collision similar to the 2017 event that produced both gravitational waves and electromagnetic waves.
Not only is iPTF 14gqr a notable event, the fact that it was observed at all was fortuitous since these phenomena are both rare and short-lived. Indeed, it was only through the observations of the supernova's early phases that the researchers could deduce the explosion's origins as a massive star.
"You need fast transient surveys and a well-coordinated network of astronomers worldwide to really capture the early phase of a supernova," says De. "Without data in its infancy, we could not have concluded that the explosion must have originated in the collapsing core of a massive star with an envelope about 500 times the radius of the sun."
The event was first seen at Palomar Observatory as part of the intermediate Palomar Transient Factory (iPTF), a nightly survey of the sky to look for transient, or short-lived, cosmic events like supernovae. Because the iPTF survey keeps such a close eye on the sky, iPTF 14gqr was observed in the very first hours after it had exploded. As the earth rotated and the Palomar telescope moved out of range, astronomers around the world collaborated to monitor iPTF 14gqr, continuously observing its evolution with a number of telescopes that today form the GROWTH network of observatories.
The Zwicky Transient Facility, the successor of iPTF at Palomar Observatory, is examining the sky even more broadly and frequently in the hopes of catching more of these rare events, which make up only one percent of all observed explosions. Such surveys, in partnership with coordinated follow-up networks like GROWTH, will enable astronomers to better understand how compact binary systems evolve from binary massive stars.
The research was primarily funded by the National Science Foundation under the PIRE GROWTH project. A full list of funding sources and co-authors can be found in the Science study, titled "A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary." In addition to De and Kasliwal, other Caltech co-authors are Gary Doran of the Jet Propulsion Laboratory; graduate student Gina Duggan; Shri Kulkarni, George Ellery Hale Professor of Astronomy and Planetary Science; and Russ Laher and Frank Masci of Caltech's Infrared Processing and Analysis Center.
For more about GROWTH, visit: http://growth.caltech.edu.
In theoretical research that could explain everything from planet formation to outflows from stars, to even the settling of volcanic ash, Caltech researchers have discovered a new mechanism to explain how the act of dust moving through gas leads to clumps of dust. While dust clumps were already known to play a role in seeding new planets and many other systems in space and on Earth, how the clumps formed was unknown until now.
Phil Hopkins, professor of theoretical astrophysics at Caltech, working with Jonathan (Jono) Squire, a former postdoctoral fellow at Caltech, began thinking about disturbances to dust moving through gas while studying how strong radiation from stars and galaxies drives dust-laden winds. Hopkins says that it was previously assumed that dust was stable in gas, meaning the dust grains would ride along with gas without much happening, or they would settle out of the gas if the particles were big enough, as is the case with soot from a fire.
"What Jono and I discovered is that dust and gas trying to move with one another is unstable and causes dust grains to come together," says Hopkins. "Soon we began to realize that these gas-dust instabilities are at play anywhere in the universe that a force pushes dust through gas, whether the forces are stellar winds, gravity, magnetism, or an electrical field." The team's simulations show material swirling together, with clumps of dust growing bigger and bigger.
"We actually started out studying dust-driven winds in space, but as we studied the problem, we noticed specific features of the instabilities that led us to think this was a more general phenomenon," says Squire, who together with Hopkins has authored four articles on their new findings, one published in The Astrophysical Journal and three in the Monthly Notices of the Royal Astronomical Society. "From here, it kind of snowballed, since we were able to study lots of different systems—galaxies, stars, planet formation, the gas close to supermassive black holes, supernovas, et cetera—and confirm our intuition. It wasn't a eureka moment but a series of eurekas that lasted about a week."
Perhaps the most notable implications for the newfound Hopkins-Squire instabilities are for the study of burgeoning planets. Planets take shape within dusty, rotating "protoplanetary" disks of gas and dust around young stars. In these disks, the dust coalesces to form bigger and bigger pebbles and boulders, then mountain-size chunks, and eventually full-grown planets.
At some point during this process, when the pieces of rock are big enough—about 1,000 kilometers in diameter—gravity takes over and smooshes the mountainous rocks into a round planet. The big mystery lies in what happens before gravity takes effect—that is, what is causing the dust particles, pebbles, and boulders to come together? Researchers once thought they might stick together in the same way dust bunnies accumulate under your bed, but there are problems with that theory.
"If you throw two pebbles together, they don't stick. They just bounce off each other," says Hopkins. "For sizes in between a millimeter and hundreds of kilometers, the grains don't stick. This is one of the biggest problems in modeling planet formation."
In the Hopkins-Squire instability model, which builds on previous models of dust-gas interactions, the formation of planetary dust clumps would begin with tiny dust grains moving through the gas orbiting in a protoplanetary disk. Gas would curl around a grain like river water around a boulder; the same thing would happen with another grain of dust nearby. These two gas flows might then interact. If there are many dust grains in relatively close proximity to one another, which is the case in planet formation, the net effect of the many resulting gas flows would be to channel the dust together into clumps.
"In our new theory, this sticking through clumping can occur for a much wider range of grain sizes than previously thought, allowing smaller grains to participate in the process and rapidly grow in size," says Squire.
"Understanding the origins of our solar system ranks among the most important problems in all of natural science, and the discovery of the Hopkins-Squire instability is a significant step toward attaining that understanding. This is an exciting development," says Caltech's Konstantin Batygin, assistant professor of planetary science and Van Nuys Page Scholar, who was not involved in the study.
The research team says these instabilities may also be important in completely different situations here on Earth. For instance, volcanic ash or raindrops interact with our atmosphere in exactly the same way that astrophysical dust interacts with its surrounding gas.
"It's very interesting to explore how these instabilities could operate in all these different scenarios," says Squire. "We're looking forward to understanding completely different instabilities in other areas of physics and applied mathematics—and, hopefully, to finding other entirely new and interesting systems where this occurs."
The research was funded by NASA and the National Science Foundation.
The four relevant studies are: "Resonant Drag Instability of Grains Streaming in Fluids," "The Resonant Drag Instability (RDI): Acoustic Modes," "Resonant drag instabilities in protoplanetary discs: the streaming instability and new, faster growing instabilities," and "Ubiquitous instabilities of dust moving in magnetized gas."
Anneila Sargent (MS '67, PhD '78), Caltech's Ira S. Bowen Professor of Astronomy, Emeritus, has made a gift to establish the Wallace L. W. Sargent Fellowship. With this fellowship, she is supporting tomorrow's scientists and engineers while also honoring her late husband. Wallace "Wal" Sargent, former Ira S. Bowen Professor of Astronomy, served on the Caltech faculty from 1966 until his death in 2012.
Read more on the Break Through campaign website.
NASA's Voyager 2 probe, currently on a journey toward interstellar space, has detected an increase in cosmic rays that originate outside our solar system. Launched in 1977, Voyager 2 is a little less than 11 billion miles (about 17.7 billion kilometers) from Earth, or more than 118 times the distance from Earth to the sun.
Since 2007 the probe has been traveling through the outermost layer of the heliosphere—the vast bubble around the sun and the planets dominated by solar material and magnetic fields. Voyager scientists have been watching for the spacecraft to reach the outer boundary of the heliosphere, known as the heliopause. Once Voyager 2 exits the heliosphere, it will become the second human-made object, after Voyager 1, to enter interstellar space.
Since late August, the Cosmic Ray Subsystem instrument on Voyager 2 has measured about a 5 percent increase in the rate of cosmic rays hitting the spacecraft compared to early August. The probe's Low-Energy Charged Particle instrument has detected a similar increase in higher-energy cosmic rays. Mission planners expect that Voyager 2 will measure an increase in the rate of cosmic rays as it approaches and crosses the boundary of the heliosphere.
"We're seeing a change in the environment around Voyager 2, there's no doubt about that," said Voyager Project Scientist Ed Stone, the David Morrisroe Professor of Physicsat Caltech. "We're going to learn a lot in the coming months, but we still don't know when we'll reach the heliopause. We're not there yet—that's one thing I can say with confidence."
Read the full story at JPL News.
The Voyager spacecraft were built by NASA's Jet Propulsion Laboratory in Pasadena, California, which continues to operate both. JPL is a division of Caltech.
One of the first pictures taken by the Samuel Oschin Telescope at Palomar, back when it opened 70 years ago, was of our nearest large neighboring galaxy, Andromeda. The photo, which showed the entirety of the spiral galaxy with its intricate lanes of dust and luminous stellar glow, was one of the best ever taken at that time. In the past, astronomers typically had to stitch together views of Andromeda from individual frames, but with the new Samuel Oschin Telescope, then known as the "48-inch," scientists could take wide-field pictures and capture all of Andromeda in one shot.
To celebrate the 70th anniversary of the telescope—which saw "first light" in late September of 1948—the Palomar team has put together a new 360-degree online tour of the telescope's dome. Viewers can scroll around the dome and learn about its various components, such as its finderscopes for guiding the main telescope, and they can watch videos of the telescope tube moving into position.
"When the 48-inch opened, astronomers could survey all of the Andromeda system and take in a deep panoramic view for the first time," says Andy Boden, deputy director of the Palomar Observatory. "The telescope lets astronomers do a broad reconnaissance of the sky rather than detailed studies. It helps one find new and interesting objects, which can then be studied in detail with other telescopes, such as the 60-inch and 200-inch Hale telescopes at Palomar."
The 360-degree tour will be featured in the Palomar Observatory museum near San Diego, and online at the Palomar Observatory website. This virtual tour and a similar virtual tour of the 200-inch Hale Telescope have been developed to let mobility-impaired people and those who live far from the observatory digitally visit the historic telescope domes for the first time.
Today, the Samuel Oschin Telescope is still a workhorse in astronomy. Its newest instrument, the Zwicky Transient Facility (ZTF), saw first light in November 2017. ZTF is scanning the entire northern sky every three nights, discovering objects that erupt or vary in brightness, including exploding stars (also known as supernovas), stars being munched on by black holes, and asteroids and comets. ZTF is funded by the National Science Foundation (NSF) and a collaboration of several other partners.
A New Way to Observe the Skies
The 48-inch telescope opened the same year as Palomar's 200-inch Hale Telescope, which was developed by George Ellery Hale—one of the founders of Caltech who built the world's largest telescope four times in a row, culminating with the 200-inch. Hale secured funding for the 200-inch in 1928, but the telescope would not be completed until 1948, 10 years after his death.
During the period the Hale Telescope was under construction, other astronomers saw the benefit of smaller telescopes that could survey the sky to find interesting targets for the larger Hale Telescope. They wanted to build so-called Schmidt telescopes, named after German optician Bernard Schmidt, which can image large portions of the sky on a single photographic plate. Caltech's Fritz Zwicky, the namesake of ZTF, and Walter Baade of Mount Wilson convinced Hale of the need to help fund such a telescope, and, after building an 18-inch Schmidt telescope at Palomar, they would go on to advocate for and develop the 48-inch, also a Schmidt telescope.
"This idea—surveying the sky with dedicated smaller telescopes and following up the interesting objects with a large telescope—is still very effective today," says George Djorgovski, professor of astronomy and executive officer for astronomy at Caltech.
From Sky Surveys to Pluto's Demise
In its 70 years of operation, the 48-inch telescope has run several sky surveys, leading to many astronomical finds. The first Palomar Observatory Sky Survey, or POSS I, took place from 1949 to 1958 and was funded by the National Geographic Society and Caltech; the second big survey, POSS II, took place from 1985 to 2000 and was funded, in part, by Eastman Kodak.
Jean Mueller, a retired telescope operator who worked for nearly 30 years at Palomar, recalls what it was like to work on the POSS II survey. "It was hard physical work, hauling boxes of photographic plates around and running up and down a lot of stairs, but I would do it all over again," she says.
She worked the night shift and, using only the dim perimeter lights on the observing floor, would swap in photographic plates into a plate loader in the telescope tube. After exposing the plates, she would load them onto a dumbwaiter, where they were lowered down to a darkroom and developed. In her spare time, Mueller discovered more than 100 supernovas and more than two dozen comets and asteroids.
"The idea was to create a giant roadmap to the sky," says Mueller.
Each photographic plate covered an area of sky equivalent to the bowl in the Big Dipper, and, ultimately, about 4,700 plates were needed during the POSS II survey to photograph the whole northern sky.
The POSS surveys also discovered thousands of galaxy clusters—the largest gravitationally bound structures in the universe. In addition to being fundamental building blocks on cosmic scales, many of these same clusters are also used as gravitational magnifying lenses that make the farthest known galaxies in the universe easier to see. The surveys also led to a catalog of stars that NASA's Hubble Space Telescope pointed at for further study.
Perhaps one of the most well-known discoveries by the 48-inch—renamed the Samuel Oschin Telescope in 1987—is that of Eris, a comet-like body about as massive as Pluto, orbiting in the fringes of our solar system. The discovery of Eris in 2005 by Mike Brown, Caltech's Richard and Barbara Rosenberg Professor of Planetary Astronomy, would ultimately lead to the demotion of Pluto from a planet to a dwarf planet.
A list of all the surveys by the Samuel Oschin Telescope, including the Palomar Transient Factory, the predecessor to ZTF, is online at: http://www.astro.caltech.edu/palomar/about/telescopes/oschin.html.
Since 2000, the 48-inch telescope has been operated robotically, and its images are taken by modern digital detectors. For example, the fully digital Palomar-Quest survey produced the Big Picture exhibit at the Griffith Observatory and pioneered the automated classification of variable objects in the sky. The large amounts of data acquired by the telescope are managed by a microwave network managed by UC San Diego. At present, the network is sending 4 terabytes of ZTF data each night to IPAC, an astronomy center at Caltech that processes and archives the data, making them available to astronomers around the world.
"The 48-inch really pioneered the modern sky surveys," says Djorgovski. "Sky surveys are now the dominant data sources in astronomy, making it a 'big data' science, and their analyses involves machine learning and other cutting-edge technologies."
Gone are the days of hauling around photographic plates. Mueller recalls that it took 15 years to complete the second big sky survey at Palomar. "Now ZTF can do the whole northern sky in three nights," she says. "That blows me away."
The new Samuel Oschin 360-degree tour was developed by media consultant Annie Mejia and Jean Mueller.
Data from NASA's Cassini spacecraft has revealed what appear to be giant dust storms in equatorial regions of Saturn's moon Titan. The discovery, described in a paper published on Sept. 24 in Nature Geoscience, makes Titan the third Solar System body, in addition to Earth and Mars, where dust storms have been observed.
The observation is helping scientists to better understand the fascinating and dynamic environment of Saturn's largest moon.
"Titan is a very active moon," said Sebastien Rodriguez, an astronomer at the Universit
Using a collection of National Science Foundation radio telescopes, researchers have confirmed that a narrow jet of material was ejected at near light speeds from a neutron star collision. The collision, which was observed August 17, 2017 and occurred 130 million light-years from Earth, initially produced gravitational waves that were observed by the Laser Interferometry Gravitational-wave Observatory (LIGO), alongside a flood of light in the form of gamma rays, X-rays, visible light, and radio waves. It was the first cosmic event to be observed in both gravitational waves and light waves.
Confirmation that a superfast jet had been produced by the neutron star collision came after radio astronomers discovered that a region of radio emission created by the merger had moved in a seemingly impossible way that only a jet could explain. The radio observations were made using the Very Long Baseline Array (VLBA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Large Array (VLA). The VLA is operated by the National Radio Astronomy Observatory (NRAO), which is closely associated with the other two telescopes involved in the discovery.
"We measured an apparent motion that is four times faster than light. That illusion, called superluminal motion, results when the jet is pointed nearly toward Earth and the material in the jet is moving close to the speed of light," says Kunal Mooley, a Caltech postdoctoral scholar with a joint appointment at the NRAO and lead author of a new study about the jet appearing online September 5 in the journal Nature. Mooley and Assistant Professor of Astronomy Gregg Hallinan were part of an international collaboration that observed and interpreted the movement of the radio emission.
"We were lucky to be able to observe this event, because if the jet had been pointed too much farther away from Earth, the radio emission would have been too faint for us to detect," says Hallinan.
Superfast jets are known to give rise to intense, short-duration gamma-ray bursts or sGRBs, predicted by theorists to be associated with neutron star collisions. The observation of a jet associated with this collision is therefore an important confirmation of theoretical expectations.
The aftermath of the merger is now also better understood: the jet likely interacted with surrounding debris, forming a broad "cocoon" of material that expanded outward and accounted for the majority of the radio signal observed soon after the collision. Later on, the observed radio emission came mainly from the jet.
Read the full story from NRAO at https://public.nrao.edu/news/superfast-jet-neutron-star-merger/.
Initially scheduled for a minimum 2.5-year primary mission, NASA's Spitzer Space Telescope has gone far beyond its expected lifetime—and is still going strong after 15 years.
Launched into a solar orbit on August 25, 2003, Spitzer was the final of NASA's four Great Observatories to reach space. The space telescope has illuminated some of the oldest galaxies in the universe, revealed a new ring around Saturn, and peered through shrouds of dust to study newborn stars and black holes. Spitzer assisted in the discovery of planets beyond our solar system, including the detection of seven Earth-size planets orbiting the star TRAPPIST-1, among other accomplishments.
"Spitzer is farther away from Earth than we ever thought it would be while still operating," said Sean Carey, manager of the Spitzer Science Center at Caltech in Pasadena, California. "This has posed some real challenges to the engineering team, and they've been extremely creative and resourceful to keep Spitzer operating far beyond its expected lifetime."
In celebration of Spitzer's 15 years in space, NASA has released two new multimedia products: The NASA Selfies app for iOS and Android, and the Exoplanet Excursions VR Experience for Oculus and Vive, as well as a 360-video version for smartphones.
Read the full story at JPL News.
JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the IPAC at Caltech. Caltech manages JPL for NASA.
NASA's InSight spacecraft, en route to a Nov. 26 landing on Mars, passed the halfway mark on Aug. 6. All of its instruments have been tested and are working well.
As of Aug. 20, the spacecraft had covered 172 million miles (277 million kilometers) since its launch 107 days ago. In another 98 days, it will travel another 129 million miles (208 million kilometers) and touch down in Mars' Elysium Planitia region, where it will be the first mission to study the Red Planet's deep interior. InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
The InSight team is using the time before the spacecraft's arrival at Mars to not only plan and practice for that critical day, but also to activate and check spacecraft subsystems vital to cruise, landing and surface operations, including the highly sensitive science instruments.
InSight's seismometer, which will be used to detect quakes on Mars, received a clean bill of health on July 19. The SEIS instrument (Seismic Experiment for Interior Structure) is a six-sensor seismometer combining two types of sensors to measure ground motions over a wide range of frequencies. It will give scientists a window into Mars' internal activity.
"We did our final performance checks on July 19, which were successful," said Bruce Banerdt, principal investigator of InSight from Jet Propulsion Laboratory, which is managed by Caltech for NASA.
Shop Weight Management Pet Products plus Free Shipping at $49 at 1800PetMeds.com!
Start: 13 Jun 2017 | End: 02 Feb 2018