Connect with us

(23 July 2020 – Northwestern University) For just the second time ever, astrophysicists have spotted a spectacular flash of ultraviolet (UV) light accompanying a white dwarf explosion.

An extremely rare type of supernova, the event is poised to offer insights into several long-standing mysteries, including what causes white dwarfs to explode, how dark energy accelerates the cosmos and how the universe creates heavy metals, such as iron.

Zwicky Transient Facility composite image of SN2019yvq (blue dot in the center of the image) in the host galaxy NGC 4441 (large yellow galaxy in the center of the image), which is nearly 140 million light-years away from Earth. SN 2019yvq exhibited a rarely observed ultraviolet flash in the days after the star exploded. (courtesy: ZTF/A. A. Miller (Northwestern University) and D. Goldstein (Caltech))

spectacular 2

Evolution of the ultraviolet and visible light emitted from SN2019yvq. Most Type Ia SNe emit far more light in the visible region of the electromagnetic spectrum than in the ultraviolet. As shown here, SN 2019yvq exhibited a spectacular ultraviolet flash just after it exploded. (courtesy: A. A. Miller/Northwestern University)

“The UV flash is telling us something very specific about how this white dwarf exploded,” said Northwestern University astrophysicist Adam Miller, who led the research. “As time passes, the exploded material moves farther away from the source. As that material thins, we can see deeper and deeper. After a year, the material will be so thin that we will see all the way into the center of the explosion.”

At that point, Miller said, his team will know more about how this white dwarf — and all white dwarfs, which are dense remnants of dead stars — explode.

The paper was published today (July 23) in The Astrophysical Journal.

Miller is a fellow in Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and program director of the Legacy Survey of Space and Time Corporation Data Science Fellowship Program.

Common event with a rare twist

Using the Zwicky Transient Facility in California, researchers first spotted the peculiar supernova in December 2019 — just a day after it exploded. The event, dubbed SN2019yvq, occurred in a relatively nearby galaxy located 140 million light-years from Earth, very close to tail of the dragon-shaped Draco constellation.

Within hours, astrophysicists used NASA’s Neil Gehrels Swift Observatory to study the phenomenon in ultraviolet and X-ray wavelengths. They immediately classified SN2019yvq as a type Ia (pronounced “one-A”) supernova, a fairly frequent event that occurs when a white dwarf explodes.

“These are some of the most common explosions in the universe,” Miller said. “But what’s special is this UV flash. Astronomers have searched for this for years and never found it. To our knowledge, this is actually only the second time a UV flash has been seen with a type Ia supernova.”

Heated mystery

The rare flash, which lasted for a couple days, indicates that something inside or nearby the white dwarf was incredibly hot. Because white dwarfs become cooler and cooler as they age, the influx of heat puzzled astronomers.

“The simplest way to create UV light is to have something that’s very, very hot,” Miller said. “We need something that is much hotter than our sun — a factor of three or four times hotter. Most supernovae are not that hot, so you don’t get the very intense UV radiation. Something unusual happened with this supernova to create a very hot phenomenon.”

Miller and his team believe this is an important clue to understanding why white dwarfs explode, which has been a long-standing mystery in the field. Currently, there are multiple competing hypotheses. Miller is particularly interested in exploring four different hypotheses, which match his team’s data analysis from SN2019yvq.

Potential scenarios that could cause a white dwarf to explode with a UV flash are:

  • A white dwarf consumes material from its companion star and becomes so massive and unstable that it explodes. The white dwarf’s expelled material and the companion star collide, causing a flash of UV emission;
  • Extremely hot radioactive material in the white dwarf’s core mixes with its outer layers, causing the outer shell to reach higher temperatures than usual;
  • An outer layer of helium ignites carbon within the white dwarf, causing an extremely hot double explosion and a UV flash;
  • Two white dwarfs merge, triggering an explosion with colliding ejecta that emit UV radiation.

“Within a year,” Miller said, “we’ll be able to figure out which one of these four is the most likely explanation.”

Earth-shattering insights

Once the researchers know what caused the explosion, they will apply those findings to learn more about planet formation and dark energy.

Because most of the iron in the universe is created by type Ia supernovae, better understanding this phenomenon could tell us more about our own planet. Iron from exploded stars, for example, formed the core of all rocky planets, including Earth.

“If you want to understand how the Earth formed, you need to understand where iron came from and how much iron was needed,” Miller said. “Understanding the ways in which a white dwarf explodes gives us a more precise understanding of how iron is created and distributed throughout the universe.”

Illuminating dark energy

White dwarfs already play an enormous role in physicists’ current understanding of dark energy as well. Physicists predict that white dwarfs all have the same brightness when they explode. So type Ia supernovae are considered “standard candles,” allowing astronomers to calculate exactly how far the explosions lie from Earth. Using supernovae to measure distances led to the discovery of dark energy, a finding recognized with the 2011 Nobel Prize in Physics.

“We don’t have a direct way to measure the distance to other galaxies,” Miller explained. “Most galaxies are actually moving away from us. If there is a type Ia supernova in a distant galaxy, we can use it to measure a combination of distance and velocity that allows us to determine the acceleration of the universe. Dark energy remains a mystery. But these supernovae are the best way to probe dark energy and understand what it is.”

And by better understanding white dwarfs, Miller believes we potentially could better understand dark energy and how fast it causes the universe to accelerate.

“At the moment, when measuring distances, we treat all of these explosions as the same, yet we have good reason to believe that there are multiple explosion mechanisms,” he said. “If we can determine the exact explosion mechanism, we think we can better separate the supernovae and make more precise distance measurements.”

Publication

The paper, “The spectacular ultraviolet flash from the peculiar type Ia supernova 2019yvq,” was partially supported by the Large Synoptic Survey Telescope Corporation, the Brinson Foundation and the Moore Foundation.

Source link

0
Continue Reading

Space

SpaceBridge rolls out Integrasys Satmotion facilitating the deployment of customer networks across Greece

SpaceBridge rolls out Integrasys Satmotion facilitating the deployment of customer

(21 September 2020 – Integrasys) SpaceBridge has successfully rolled out an ASAT-II Redundant Hub and over 100 sites across Hellas SAT.

To facilitate the deployment of the network and minimize staff time and efforts on-site, SpaceBridge selected Satmotion Pocket, Integrasys’s industry-leading Auto Commissioning tool. Satmotion Pocket is a VSAT auto-commissioning system that minimizes deployment time and effort while ensuring the highest quality and interference-free installation for optimal performance. It is a software-based solution that simplifies and guides installers by providing feedback on important key performance indicators (KPI) such as Copol, Xpol and Adjacent Satellite Interference, verifying that the antenna and receive/transmit chain of the solutions are optimally installed and allowing sites to generate revenue earlier.

(courtesy: Integrasys)

David Gelerman, President and CEO of Spacebridge; “Our goal at SpaceBridge is to ensure our customers can rapidly monetize upon the offering of their value-added services. The Satmotion Pocket by Integrasys proved very effective in that it allowed our partners to provide high-quality installations efficiently resulting in much faster deployment, saving time and resources, and delivering revenue sooner. Based on this roll-out, we envision a bright future of collaboration between our two companies.”

Alvaro Sanchez; “For us partnering with SpaceBridge has been a great pleasure, it opens the door to new customers who can tangibly benefit from our technology for simplifying the access while generating additional revenue and faster time to market, and commissioning. SpaceBridge is a great company to work with a great leader & engineer as CEO; they have great technology for connecting new networks, ASAT is a fantastic product.”

Satmotion Pocket developed by Integrasys for ASAT System with its accurate performance enabled SpaceBridge customers to deploy the VSAT network rapidly, easily, and at low cost. Satmotion Pocket is supported on the smartphone, thanks to its user-friendly interface, it does not require VSAT experts to carry out the installation. The time and cost savings are remarkable, as the field technician does not need to call the NOC/Hub, carry a satellite phone, or spectrum analyzer, in a few minutes the VSAT is up and running providing revenue to Space Bridge customers.

About Integrasys

Founded in 1990 by Hewlett Packard engineers, Integrasys specializes in providing satellite spectrum monitoring systems for the satellite, telecommunication, and broadcast markets. Its solutions enable fast and efficient installation and monitoring, helping reduce both errors and costs.

Integrasys is a fast-growing company which it has been awarded with the most innovative technology award in 2018 at the Satellite show by WTA; it has increased 30% in revenue each year during the last three years, and last year it has tripled its profit.

Source link

0
Continue Reading

Space

NASA’s new Mars rover will use X-rays to hunt fossils

NASAs new Mars rover will use X rays to hunt fossils

(22 September 2020 – JPL) NASA’s Mars 2020 Perseverance rover has a challenging road ahead: After having to make it through the harrowing entry, descent, and landing phase of the mission on Feb. 18, 2021, it will begin searching for traces of microscopic life from billions of years back.

That’s why it’s packing PIXL, a precision X-ray device powered by artificial intelligence (AI).

Short for Planetary Instrument for X-ray Lithochemistry, PIXL is a lunchbox-size instrument located on the end of Perseverance’s 7-foot-long (2-meter-long) robotic arm. The rover’s most important samples will be collected by a coring drill on the end of the arm, then stashed in metal tubes that Perseverance will deposit on the surface for return to Earth by a future mission.

In this illustration, NASA’s Perseverance Mars rover uses the Planetary Instrument for X-ray Lithochemistry (PIXL). Located on the turret at the end of the rover’s robotic arm, the X-ray spectrometer will help search for signs of ancient microbial life in rocks. (courtesy: NASA/JPL-Caltech)

nasas 2

PIXL requires pictures of its rock targets to autonomously position itself. Light diodes encircle its opening and take pictures of rock targets when the instrument is working at night. Using artificial intelligence, PIXL relies on the images to determine how far away it is from a target to be scanned. (courtesy: NASA/JPL-Caltech)

Nearly every mission that has successfully landed on Mars, from the Viking landers to the Curiosity rover, has included an X-ray fluorescence spectrometer of some kind. One major way PIXL differs from its predecessors is in its ability to scan rock using a powerful, finely-focused X-ray beam to discover where – and in what quantity – chemicals are distributed across the surface.

“PIXL’s X-ray beam is so narrow that it can pinpoint features as small as a grain of salt. That allows us to very accurately tie chemicals we detect to specific textures in a rock,” said Abigail Allwood, PIXL’s principal investigator at NASA’s Jet Propulsion Laboratory in Southern California.

Rock textures will be an essential clue when deciding which samples are worth returning to Earth. On our planet, distinctively warped rocks called stromatolites were made from ancient layers of bacteria, and they are just one example of fossilized ancient life that scientists will be looking for.

nasas 3

A device with six mechanical legs, the hexapod is a critical part of the PIXL instrument aboard NASA’s Perseverance Mars rover. The hexapod allows PIXL to make slow, precise movements to get closer to and point at specific parts of a rock’s surface. This GIF has been considerably sped up to show how the hexapod moves. (courtesy: NASA/JPL-Caltech)

An AI-Powered Night Owl

To help find the best targets, PIXL relies on more than a precision X-ray beam alone. It also needs a hexapod – a device featuring six mechanical legs connecting PIXL to the robotic arm and guided by artificial intelligence to get the most accurate aim. After the rover’s arm is placed close to an interesting rock, PIXL uses a camera and laser to calculate its distance. Then those legs make tiny movements – on the order of just 100 microns, or about twice the width of a human hair – so the device can scan the target, mapping the chemicals found within a postage stamp-size area.

“The hexapod figures out on its own how to point and extend its legs even closer to a rock target,” Allwood said. “It’s kind of like a little robot who has made itself at home on the end of the rover’s arm.”

Then PIXL measures X-rays in 10-second bursts from a single point on a rock before the instrument tilts 100 microns and takes another measurement. To produce one of those postage stamp-size chemical maps, it may need to do this thousands of times over the course of as many as eight or nine hours.

That timeframe is partly what makes PIXL’s microscopic adjustments so critical: The temperature on Mars changes by more than 100 degrees Fahrenheit (38 degrees Celsius) over the course of a day, causing the metal on Perseverance’s robotic arm to expand and contract by as much as a half-inch (13 millimeters). To minimize the thermal contractions PIXL has to contend with, the instrument will conduct its science after the Sun sets.

“PIXL is a night owl,” Allwood said. “The temperature is more stable at night, and that also lets us work at a time when there’s less activity on the rover.”

nasas 4

PIXL opens its dust cover during testing at NASA’s Jet Propulsion Laboratory. One of seven instruments on NASA’s Perseverance Mars rover, PIXL is located on the end of the rover’s robotic arm. (courtesy: NASA/JPL-Caltech)

X-rays for Art and Science

Long before X-ray fluorescence got to Mars, it was used by geologists and metallurgists to identify materials. It eventually became a standard museum technique for discovering the origins of paintings or detecting counterfeits.

“If you know that an artist typically used a certain titanium white with a unique chemical signature of heavy metals, this evidence might help authenticate a painting,” said Chris Heirwegh, an X-ray fluorescence expert on the PIXL team at JPL. “Or you can determine if a particular kind of paint originated in Italy rather than France, linking it to a specific artistic group from the time period.”

For astrobiologists, X-ray fluorescence is a way to read stories left by the ancient past. Allwood used it to determine that stromatolite rocks found in her native country of Australia are some of the oldest microbial fossils on Earth, dating back 3.5 billion years. Mapping out the chemistry in rock textures with PIXL will offer scientists clues to interpret whether a sample could be a fossilized microbe.

More About the Mission

A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will also characterize the planet’s climate and geology, pave the way for human exploration of the Red Planet, and be the first planetary mission to collect and cache Martian rock and regolith (broken rock and dust). Subsequent missions, currently under consideration by NASA in cooperation with the European Space Agency, would send spacecraft to Mars to collect these cached samples from the surface and return them to Earth for in-depth analysis.

The Mars 2020 mission is part of a larger program that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with returning astronauts to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through NASA’s Artemis lunar exploration plans.

JPL, which is managed for NASA by Caltech in Pasadena, California, built and manages operations of the Perseverance and Curiosity rovers.

Source link

0
Continue Reading

Space

NRAO joins space mission to the far side of the Moon to explore the early universe

NRAO joins space mission to the far side of the

(22 September 2020 – NRAO) The National Radio Astronomy Observatory (NRAO) has joined a new NASA space mission to the far side of the Moon to investigate when the first stars began to form in the early universe.

Artist illustration of the Dark Ages Polarimetry Pathfinder (DAPPER), which will look for faint radio signals from the early universe while operating in a low lunar orbit. Its specialized radio receiver and high-frequency antenna are currently being developed by NRAO. (courtesy: NRAO/AUI/NSF, Sophia Dagnello)

The universe was dark and foggy during its “dark ages,” just 380 thousand years after the Big Bang. There were no light-producing structures yet like stars and galaxies, only large clouds of hydrogen gas. As the universe expanded and started to cool down, gravity drove the formation of the stars and black holes, which ended the dark ages and initiated the “cosmic dawn,” tens of millions of years later.

To learn more about that dark period of the cosmos and understand how and when the first stars began to form, astronomers are trying to catch energy produced by these hydrogen clouds in the form of radio waves, via the so-called 21-centimeter line.

But picking up signals from the early universe is extremely challenging. They are mostly blocked by the Earth’s atmosphere, or drowned out by human-generated radio transmissions. That’s why a team of scientists and engineers have decided to send a small spacecraft to lunar orbit and measure this signal while traversing the far side of the Moon, which is radio-quiet.

The spacecraft, called the Dark Ages Polarimetry Pathfinder (DAPPER), will be designed to look for faint radio signals from the early universe while operating in a low lunar orbit. Its specialized radio receiver and high-frequency antenna are currently being developed by a team at the NRAO’s Central Development Laboratory (CDL) in Charlottesville, Virginia, led by senior research engineer Richard Bradley.

“No radio telescope on Earth is currently able to definitively measure and confirm the very faint neutral hydrogen signal from the early universe, because there are so many other signals that are much brighter,” said Bradley. “At CDL we are developing specialized techniques that enhance the measurement process used by DAPPER to help us separate the faint signal from all the noise.” This project builds upon the work of Marian Pospieszalski who developed flight-ready low noise amplifiers at the CDL in the 1990s for the highly-successful Wilkinson Microwave Anisotropy Probe (WMAP), a spacecraft that gave the most precise figure yet for the age of the universe.

DAPPER will be part of the NASA Artemis program with the goal of landing “the first woman and the next man” on the Moon by 2024. It will likely be launched from the vicinity of the Lunar Gateway, the planned space station in lunar orbit intended to serve as a communication hub and science laboratory. Because it is able to piggy-back off of the surging interest in sending humans to lunar soil, DAPPER will be much cheaper to build and more compact than a full-scale NASA mission.

NRAO will spend the coming two years designing and developing a prototype for the DAPPER receiver, after which it will go to the Space Sciences Laboratory at UC Berkeley for space environmental testing.

“NRAO is very pleased to be working on this important initiative,” said Tony Beasley, director of the NRAO and Associated Universities Inc. vice president for Radio Astronomy Operations. “DAPPER’s contributions to the success of NASA’s ARTEMIS mission will build on the rapid growth of space-based radio astronomy research we’ve seen over the past decade. As the leading radio astronomy organization in the world, NRAO always looks for new horizons, and DAPPER is the start of an exciting field.”

DAPPER is a collaboration between the universities of Colorado-Boulder and California-Berkeley, the National Radio Astronomy Observatory, Bradford Space Inc., and the NASA Ames Research Center. Jack Burns of the University of Colorado Boulder is Principal Investigator and Science Team Chair. Project website for DAPPER.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Source link

0
Continue Reading

Trending