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Researchers Rewind the Clock to Calculate Age and Site of Supernova Blast
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By NASA
NASA, ESA, R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and M. Mutchler and R. Avila (STScI) This image, released on Feb. 24, 2017, shows Supernova 1987a (center) surrounded by dramatic red clouds of gas and dust within the Large Magellanic Cloud. This supernova, first discovered on Feb. 23, 1987, blazed with the power of 100 million Suns. Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it was the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.
Image credit: NASA, ESA, R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and M. Mutchler and R. Avila (STScI)
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
New findings using data from NASA’s IXPE (Imaging X-ray Polarimetry Explorer) mission offer unprecedented insight into the shape and nature of a structure important to black holes called a corona.
A corona is a shifting plasma region that is part of the flow of matter onto a black hole, about which scientists have only a theoretical understanding. The new results reveal the corona’s shape for the first time, and may aid scientists’ understanding of the corona’s role in feeding and sustaining black holes.
This illustration of material swirling around a black hole highlights a particular feature, called the “corona,” that shines brightly in X-ray light. In this depiction, the corona can be seen as a purple haze floating above the underlying accretion disk, and extending slightly inside of its inner edge. The material within the inner accretion disk is incredibly hot and would glow with a blinding blue-white light, but here has been reduced in brightness to make the corona stand out with better contrast. Its purple color is purely illustrative, standing in for the X-ray glow that would not be obvious in visible light. The warp in the disk is a realistic representation of how the black hole’s immense gravity acts like an optical lens, distorting our view of the flat disk that encircles it. NASA/Caltech-IPAC/Robert Hurt Many black holes, so named because not even light can escape their titanic gravity, are surrounded by accretion disks, debris-cluttered whirlpools of gas. Some black holes also have relativistic jets – ultra-powerful outbursts of matter hurled into space at high speed by black holes that are actively eating material in their surroundings.
Less well known, perhaps, is that snacking black holes, much like Earth’s Sun and other stars, also possess a superheated corona. While the Sun’s corona, which is the star’s outermost atmosphere, burns at roughly 1.8 million degrees Fahrenheit, the temperature of a black hole corona is estimated at billions of degrees.
Astrophysicists previously identified coronae among stellar-mass black holes – those formed by a star’s collapse – and supermassive black holes such as the one at the heart of the Milky Way galaxy.
“Scientists have long speculated on the makeup and geometry of the corona,” said Lynne Saade, a postdoctoral researcher at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and lead author of the new findings. “Is it a sphere above and below the black hole, or an atmosphere generated by the accretion disk, or perhaps plasma located at the base of the jets?”
Enter IXPE, which specializes in X-ray polarization, the characteristic of light that helps map the shape and structure of even the most powerful energy sources, illuminating their inner workings even when the objects are too small, bright, or distant to see directly. Just as we can safely observe the Sun’s corona during a total solar eclipse, IXPE provides the means to clearly study the black hole’s accretion geometry, or the shape and structure of its accretion disk and related structures, including the corona.
“X-ray polarization provides a new way to examine black hole accretion geometry,” Saade said. “If the accretion geometry of black holes is similar regardless of mass, we expect the same to be true of their polarization properties.”
IXPE demonstrated that, among all black holes for which coronal properties could be directly measured via polarization, the corona was found to be extended in the same direction as the accretion disk – providing, for the first time, clues to the corona’s shape and clear evidence of its relationship to the accretion disk. The results rule out the possibility that the corona is shaped like a lamppost hovering over the disk.
The research team studied data from IXPE’s observations of 12 black holes, among them Cygnus X-1 and Cygnus X-3, stellar-mass binary black hole systems about 7,000 and 37,000 light-years from Earth, respectively, and LMC X-1 and LMC X-3, stellar-mass black holes in the Large Magellanic Cloud more than 165,000 light-years away. IXPE also observed a number of supermassive black holes, including the one at the center of the Circinus galaxy, 13 million light-years from Earth, and those in galaxies NGC 1068 and NGC 4151, 47 million light-years away and nearly 62 million light-years away, respectively.
Stellar mass black holes typically have a mass roughly 10 to 30 times that of Earth’s Sun, whereas supermassive black holes may have a mass that is millions to tens of billions of times larger. Despite these vast differences in scale, IXPE data suggests both types of black holes create accretion disks of similar geometry.
That’s surprising, said Marshall astrophysicist Philip Kaaret, principal investigator for the IXPE mission, because the way the two types are fed is completely different.
“Stellar-mass black holes rip mass from their companion stars, whereas supermassive black holes devour everything around them,” he said. “Yet the accretion mechanism functions much the same way.”
That’s an exciting prospect, Saade said, because it suggests that studies of stellar-mass black holes – typically much closer to Earth than their much more massive cousins – can help shed new light on properties of supermassive black holes as well.
The team next hopes to make additional examinations of both types.
Saade anticipates there’s much more to glean from X-ray studies of these behemoths. “IXPE has provided the first opportunity in a long time for X-ray astronomy to reveal the underlying processes of accretion and unlock new findings about black holes,” she said.
The complete findings are available in the latest issue of The Astrophysical Journal.
More about IXPE
IXPE, which continues to provide unprecedented data enabling groundbreaking discoveries about celestial objects across the universe, is a joint NASA and Italian Space Agency mission with partners and science collaborators in 12 countries. IXPE is led by Marshall. Ball Aerospace, headquartered in Broomfield, Colorado, manages spacecraft operations together with the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder.
Learn more about IXPE’s ongoing mission here:
https://www.nasa.gov/ixpe
Elizabeth Landau
NASA Headquarters
elizabeth.r.landau@nasa.gov
202-358-0845
Lane Figueroa
NASA’s Marshall Space Flight Center
256-544-0034
lane.e.figueroa@nasa.gov
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Last Updated Oct 17, 2024 EditorBeth RidgewayLocationMarshall Space Flight Center Related Terms
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By NASA
In October 1604, a new star appeared in the sky, puzzling astronomers of the day. First observed on Oct. 9, German astronomer Johannes Kepler (1571-1630) began his observations on Oct. 17 and tracked the new star for over a year. During that time, it brightened to magnitude -2.5, outshining Jupiter, and for several weeks remained visible in the daytime. Publication of his detailed observations in 1606 led astronomers to call the star Kepler’s Supernova, today formally designated as supernova SN 1604. Astronomers of the day did not know what caused the star’s sudden appearance and eventual disappearance, but the phenomenon helped shape European cosmology toward the heliocentric model proposed by Polish astronomer Nicolaus Copernicus half a century earlier. Today, astronomers designate SN 1604 as a Type Ia supernova, resulting from the explosion of a white dwarf star, and use ground-based and space-based telescopes to study its remnants.
Left: Portrait of Johannes Kepler by August Köhler. Middle: Kepler’s book about his observations of the 1604 supernova open to the page depicting the location of the new star. Right: Closeup of Kepler’s illustration of the location of the new star, designated N, in the constellation Ophiuchus near the right foot of the serpent-bearer.
Italian astronomer Lodovico delle Colombo first observed the supernova in the constellation Ophiuchus on Oct. 9. Kepler, then working in Prague, heard rumors of the new star but did not observe it until Oct. 17. He continued to monitor the star for over a year, inspired by the earlier work of Danish astronomer Tycho Brahe’s observations of a similar phenomenon, the 1572 supernova. The new star quickly brightened to magnitude -2.5, outshining Jupiter, and for three weeks could be seen in the daytime before finally fading into obscurity in March 1606. Kepler could only make naked eye observations, since Italian astronomer Galileo Galilei didn’t turn his newly invented telescope to the skies for another four years after SN 1604 faded from view.
Later in 1606, Kepler summarized his observations in his book De Stella nova in pede Serpentarii (On the New Star in Ophiuchus’ Foot), published in Prague. SN 1604 is believed to be about 20,000 light years away, near the edge of a dark nebula complex. Kepler and his contemporaries observed not only the last known supernova to occur in the Milky Way Galaxy but also the last supernova visible to the naked eye until 1987. That one, Supernova 1987A, appeared in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way.
A Type Ia supernova results from a white dwarf drawing in material from a nearby red giant star, the additional mass leading to a runaway thermonuclear explosion.
Astronomers today understand that what Kepler and others believed as the birth of a new star actually represented the violent death of a star. Astronomers today classify supernovas according to their characteristics, and SN 1604 belongs to the group known as Type Ia supernovas, typically found in binary star systems composed of a white dwarf and a red giant. The gravitation force of the white dwarf draws in material from its larger less dense companion until it reaches a critical mass, around 1.4 times the mass of our Sun. At that point, a runaway thermonuclear chain reaction begins, causing a release of tremendous amounts of energy, including light, that we see as a sudden brightening of an otherwise dim star.
Images of Kepler’s supernova remnants in different portions of the electromagnetic spectrum. Left: X-ray image from the Chandra X-ray Observatory. Middle: Visible image from the Hubble Space Telescope. Right: Infrared image from the Spitzer Space Telescope.
Supernova explosions leave remnants behind and those of SN 1604 remain visible today. Ground-based and space-based instruments using different parts of the electromagnetic spectrum study these remnants to gain a better understanding of their origins. The remnants of SN 1604 emit energy most strongly in the radio and X-ray parts of the electromagnetic spectrum. In recent years, astronomers have used Type Ia supernovas to determine the rate of expansion of the universe. Because Type Ia supernovas all occur in stars of about 1.4 solar masses, they give out about the same amount of light. This makes them useful as distance indicators – if one Type Ia supernova is dimmer than another one, it is further away by an amount that astronomers can calculate. Based on this information, astronomers believe that the expansion of the universe is accelerating, possibly caused by the presence of a mysterious substance called dark energy.
Events in world history in 1604:
January 1 – First performance of William Shakespeare’s play A Midsummer’s Night’s Dream.
March 22 – Karl IX begins his rule as King of Sweden.
August 5 – Sokolluzade Mehmed Pasha becomes the new Ottoman Grand Vizier in Constantinople.
August 18 – England and Spain sign the Treaty of London, ending their 20-year war.
September 1 – Sri Guru Granth Sahib, Sikhism’s religious text, is installed at Hamandir Sahib in Amritsar, India.
October 4 – Emperor of Ethiopia Za Dengel is killed in battle with the forces of Za Sellase, who restores his cousin Yaqob to the throne.
November 1 – First performance of William Shakespeare’s tragedy Othello.
December 29 – A magnitude 8.1 earthquake shakes the Taiwan Strait causing significant damage.
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By European Space Agency
XRISM revealed the structure, motion and temperature of the material around a supermassive black hole and in a supernova remnant in unprecedented detail. Astronomers presented the first scientific results of the new X-ray telescope today, less than a year after the telescope’s launch.
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By NASA
5 Min Read Reinventing the Clock: NASA’s New Tech for Space Timekeeping
The Optical Atomic Strontium Ion Clock is a higher-precision atomic clock that is small enough to fit on a spacecraft. Credits: NASA/Matthew Kaufman Here on Earth, it might not matter if your wristwatch runs a few seconds slow. But crucial spacecraft functions need accuracy down to one billionth of a second or less. Navigating with GPS, for example, relies on precise timing signals from satellites to pinpoint locations. Three teams at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are at work to push timekeeping for space exploration to new levels of precision.
One team develops highly precise quantum clock synchronization techniques to aid essential spacecraft communication and navigation. Another Goddard team is working to employ the technique of clock synchronization in space-based platforms to enable telescopes to function as one enormous observatory. The third team is developing an atomic clock for spacecraft based on strontium, a metallic chemical element, to enable scientific observations not possible with current technology. The need for increasingly accurate timekeeping is why these teams at NASA Goddard, supported by the center’s Internal Research and Development program, hone clock precision and synchronization with innovative technologies like quantum and optical communications.
Syncing Up Across the Solar System
“Society requires clock synchronization for many crucial functions like power grid management, stock market openings, financial transactions, and much more,” said Alejandro Rodriguez Perez, a NASA Goddard researcher. “NASA uses clock synchronization to determine the position of spacecraft and set navigation parameters.”
If you line up two clocks and sync them together, you might expect that they will tick at the same rate forever. In reality, the more time passes, the more out of sync the clocks become, especially if those clocks are on spacecraft traveling at tens of thousands of miles per hour. Rodriguez Perez seeks to develop a new way of precisely synchronizing such clocks and keeping them synced using quantum technology.
Work on the quantum clock synchronization protocol takes place in this lab at NASA’s Goddard Space Flight Center in Greenbelt, Md.NASA/Matthew Kaufman In quantum physics, two particles are entangled when they behave like a single object and occupy two states at once. For clocks, applying quantum protocols to entangled photons could allow for a precise and secure way to sync clocks across long distances.
The heart of the synchronization protocol is called spontaneous parametric down conversion, which is when one photon breaks apart and two new photons form. Two detectors will each analyze when the new photons appear, and the devices will apply mathematical functions to determine the offset in time between the two photons, thus synchronizing the clocks.
While clock synchronization is currently done using GPS, this protocol could make it possible to precisely synchronize clocks in places where GPS access is limited, like the Moon or deep space.
Syncing Clocks, Linking Telescopes to See More than Ever Before
When it comes to astronomy, the usual rule of thumb is the bigger the telescope, the better its imagery.
“If we could hypothetically have a telescope as big as Earth, we would have incredibly high-resolution images of space, but that’s obviously not practical,” said Guan Yang, an optical physicist at NASA Goddard. “What we can do, however, is have multiple telescopes in various locations and have each telescope record the signal with high time precision. Then we can stich their observations together and produce an ultra-high-res image.”
The idea of linking together the observations of a network of smaller telescopes to affect the power of a larger one is called very long baseline interferometry, or VLBI.
For VLBI to produce a whole greater than the sum of its parts, the telescopes need high-precision clocks. The telescopes record data alongside timestamps of when the data was recorded. High-powered computers assemble all the data together into one complete observation with greater detail than any one of the telescopes could achieve on its own. This technique is what allowed the Event Horizon Telescope’s network of observatories to produce the first image of a black hole at the center of our galaxy.
The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Although the telescopes making up the EHT are not physically connected, they are able to synchronize their recorded data with atomic clocks.EHT Collaboration Yang’s team is developing a clock technology that could be useful for missions looking to take the technique from Earth into space which could unlock many more discoveries.
An Optical Atomic Clock Built for Space Travel
Spacecraft navigation systems currently rely on onboard atomic clocks to obtain the most accurate time possible. Holly Leopardi, a physicist at NASA Goddard, is researching optical atomic clocks, a more precise type of atomic clock.
While optical atomic clocks exist in laboratory settings, Leopardi and her team seek to develop a spacecraft-ready version that will provide more precision.
The team works on OASIC, which stands for Optical Atomic Strontium Ion Clock. While current spacecraft utilize microwave frequencies, OASIC uses optical frequencies.
The Optical Atomic Strontium Ion Clock is a higher-precision atomic clock that is small enough to fit on a spacecraft.NASA/Matthew Kaufman “Optical frequencies oscillate much faster than microwave frequencies, so we can have a much finer resolution of counts and more precise timekeeping,” Leopardi said.
The OASIC technology is about 100 times more precise than the previous state-of-the-art in spacecraft atomic clocks. The enhanced accuracy could enable new types of science that were not previously possible.
“When you use these ultra-high precision clocks, you can start looking at the fundamental physics changes that occur in space,” Leopardi said, “and that can help us better understand the mechanisms of our universe.”
The timekeeping technologies unlocked by these teams, could enable new discoveries in our solar system and beyond.
More on cutting-edge technology development at NASA Goddard By Matthew Kaufman, with additional contributions from Avery Truman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 18, 2024 EditorRob GarnerContactRob Garnerrob.garner@nasa.govLocationGoddard Space Flight Center Related Terms
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