The discovery of pulsars - a graduate student's tale
In this talk I will describe how pulsars were accidentally discovered, and reflect on several instances where they were 'nearly' discovered. I will highlight the implications for new telescopes with high data rates.
Neutron Stars, Pulsars, and Magnetars
Neutron Stars, Pulsars, and Magnetars are the most extreme objects in the Universe that aren't Black Holes. Their extreme densities make neutron stars the densest solid bodies in the Universe ultra-powerful magnetic fields. When these fields sweep along our line of sight, we see them as Pulsars. Some Pulsars have have extremely strong magnetic fields. We call these objects Magnetars. And when a Magnetar has a star quake, the most violent explosions this side of a Supernova take place. 🔔 Subscribe for more: https://www.youtube.com/christianready?sub_confirmation=1 🖖 Share this video with a fellow space traveler: https://youtu.be/VsliMyrvGDI 🔴 Watch my most recent upload: https://goo.gl/QbRcE2 🚀 Help me improve the channel by joining the community on Patreon
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Did we really find a “habitable” exoplanet? | Night Sky News September 2019
It's Night Sky News time again where we recap everything that's happened in space news this past month and everything to look out for in the sky in the coming month. #stargazing #spacenews #astronomy My new book 'Space: The 10 Things You Should Know' is out now worldwide (except US & Canada) on September 5th 2019! You can pre-order it (UK only) from amazon here: http://bit.ly/SpaceDrBecky News on US & Canadian publication coming soon! Don't forget to subscribe and click the little bell icon to be notified when I post a new video! ------ False dawn - 00:26
Jupiter, Saturn and the Moon - 02:28
Draconids - 03:18
Juno’s snap of Io shadow - 03
Chandrayaan-2 loss - 04:35
The most massive neutron star - 06:11 - Cromartie et al. (2019) - https://arxiv.org/pdf/1904.06759.pdf & https://arxiv.org/pdf/1304.6875.pdf
Did we really find a habitable exoplanet in K2-18b? -11:30 - https://arxiv.org/pdf/1909.04642.pdf & https://www.nature.com/articles/s41550-019-0878-9 --------- Dr. Becky also presents videos on Sixty Symbols: https://www.youtube.com/user/sixtysymbols
and Deep Sky Videos: https://www.youtube.com/user/DeepSkyVideos Dr Becky Smethurst is an astrophysicist researching galaxies and supermassive black holes at Christ Church at the University of Oxford. http://drbecky.uk.com
https://rebeccasmethurst.co.uk ------------ News Theme 1 by Audionautix is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
10 Unsettling Astronomical Incidents and Phenomena
An exploration of ten of the most unsettling astrophysical events including Dyson Sphere candidates, a star containing plutonium, the Wow! Signal and others. https://www.patreon.com/johnmichaelgodier https://www.youtube.com/eventhorizonshow Papers: "Pulsar Positioning System: A quest for evidence of extraterrestrial engineering", Clement Vidal, 2017 https://arxiv.org/abs/1704.03316 "Fast Radio Bursts from Extragalactic Light Sails", Lingham and Loeb, 2017 https://arxiv.org/abs/1701.01109 "Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars", Borra and Trottier, 2016 https://arxiv.org/abs/1610.03031 Music: Cylinder Eight by Chris Zabriskie is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
Artist: http://chriszabriskie.com/ Cylinder Five by Chris Zabriskie is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
Artist: http://chriszabriskie.com/ "Night Forever" by Miguel Johnson https://migueljohnson.bandcamp.com/ Cylinder Three by Chris Zabriskie is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
New Simulation Creates "Pulsar in a Box"
Scientists studying what amounts to a computer-simulated "pulsar in a box" are gaining a more detailed understanding of the complex, high-energy environment around spinning neutron stars, also called pulsars. The model traces the paths of charged particles in magnetic and electric fields near the neutron star, revealing behaviors that may help explain how pulsars emit gamma-ray and radio pulses with ultraprecise timing. A pulsar is the crushed core of a massive star that exploded as a supernova. The core is so compressed that more mass than the Sun's squeezes into a ball no wider than Manhattan Island in New York City. This process also revvs up its rotation and strengthens its magnetic and electric fields. Various physical processes ensure that most of the particles around a pulsar are either electrons or their antimatter counterparts, positrons. To trace the behavior and energies of these particles, the researchers used a comparatively new type of pulsar model called a "particle in cell" (PIC) simulation. The PIC technique lets scientists explore the pulsar from first principles, starting with a spinning, magnetized neutron star. The computer code injects electrons and positrons at the pulsar's surface and tracks how they interact with the electric and magnetic fields. It's computationally intensive because the particle motions affect the fields and the fields affect the particles, and everything is moving near the speed of light. The simulation shows that most of the electrons tend to race outward from the magnetic poles. Some medium-energy electrons scatter wildly, even heading back to the pulsar. The positrons, on the other hand, mostly flow out at lower latitudes, forming a relatively thin structure called the current sheet. In fact, the highest-energy positrons here -- less than 0.1 percent of the total -- are capable of producing gamma rays similar to those detected by NASA's Fermi Gamma-ray Space Telescope, which has discovered 216 gamma-ray pulsars. The simulation ran on the Discover supercomputer at NASA's Center for Climate Simulation at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the Pleiades supercomputer at NASA's Ames Research Center in Silicon Valley, California. The model actually tracks "macroparticles," each of which represents many trillions of electrons or positrons. Credit: NASA's Goddard Space Flight Center Music: "Reaching for the Horizon" and "Leaving Earth" from Killer Tracks This video is public domain and along with other supporting visualizations can be downloaded from the Scientific Visualization Studio at: http://svs.gsfc.nasa.gov/13058 If you liked this video, subscribe to the NASA Goddard YouTube channel: http://www.youtube.com/NASAExplorer Follow NASA’s Goddard Space Flight Center
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John Kirk: Pulsar Winds
John Kirk (Heidelberg) Pulsar Winds Abstract:
Pulsar Winds and the nebulae which they energize (PWN) are among the most enigmatic objects in astrophysics. They consist of a relativistic, magnetized, electron-positron plasma that forms a compact cloud surrounding young pulsars. Their nonthermal synchrotron and inverse-Compton emission is detected from the radio band to very high energy (TeV) gamma-rays, where they are the dominant galactic source population. The radio-to-infrared spectra of PWN are flat, indicating a remarkably efficient particle acceleration mechanism, able to transfer most of the system energy into a tiny fraction of particles. Despite decades of research, the mechanism responsible for accelerating these particles has remained elusive, and poses one of the greatest challenges in particle acceleration theory.
In this talk I will give an introduction to the physics of pulsar winds, and describe recent work on the acceleration mechanisms thought to be at work. These include not only variants of the well-known first-order Fermi mechanism, but also "inductive acceleration", which may explain the mysterious gamma-ray flares from the Crab Nebula, discovered in 2011 by the Agile and Fermi satellites.
Einstein's Gravity Theory Holds Up In Three-Star System
Scientists understand gravity pretty well when it comes to two objects, but add a third, and you’ve got chaos—a system that’s impossible to explain with our simplest equations. But you also have a way to test the limits of Einstein’s theory of gravity. You’re probably aware of the fact that there are a lot of outstanding questions about our universe—like what is dark energy, what is dark matter, and why can’t one unified physics theory explain both the biggest and smallest objects in the universe?
http://www.wochit.com This video was produced by YT Wochit Tech using http://wochit.com
Astro News Bytes: A Plasma Lensed Pulsar
The wake of gas from its brown dwarf companion has magnified this tiny pulsar for closer scrutiny. You can get the whole story and more at Astronomy.com http://www.astronomy.com/news/2018/05/astronomers-get-a-close-look-at-a-distant-pulsar Astronomy magazine is the world’s best-selling astronomy magazine, offering you the most exciting visually stunning thorough, and timely coverage of the heavens above. Each monthly issue includes expert science reporting, vivid color photography, complete sky-event coverage, spot-on observing tips, informative telescope reviews, and more. Astronomy.com features daily news and weekly observing tips, as well as our Picture of the Day. We also invite you to check out our blogs, podcasts, and more. All of this comes in an easy-to-understand user-friendly style that's perfect for astronomers at any level. Like Astronomy magazine on FACEBOOK:
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Pulsars and Magnetars
If you’ve ever heard of the phrase two sides of the same coin, you know it means two things that at first appear to be unrelated are actually parts of the same thing. Now, a fundamental example can be found in the deep recesses of space in the form of a neutron star. A neutron star comes from a large star that has run out of fuel, and exploded as a supernova. As gravity forces the star to collapse to the size of a small city, the star becomes so dense that a single teaspoon of the collapsed star would have as much mass as a mountain. The star’s core, now a neutron star, can be rotating as fast as 10 times a second or more. Over time the rotation of the core can start speeding up by pulling matter from its surroundings, rotating over 700 times a second!
Some neutron stars, called radio pulsars, have strong magnetic fields and emit radio waves in predictable, reliable pulses. Other neutron stars have even stronger magnetic fields, displaying violent, high-energy outbursts of X-ray and gamma ray light. These are called 'magnetars', and their magnetic fields are the strongest known in the universe, a trillion time stronger than that of our sun. Since the 1970s, scientists have treated pulsars and magnetars as two distinct populations of objects. But in the last decade evidence has emerged that shows they might sometimes be stages in the evolution of a single object. That’s right – a neutron star might just be two sides of the same coin – first it’s a radio pulsar and later becomes a magnetar. Or maybe it’s the other way around. Some scientists argue that objects like magnetars gradually stop emitting X-rays and gamma rays over time. Others propose the opposite theory: that the radio pulsar comes first and then, over time, a magnetic field emerges from the neutron star causing those magnetar-like outbursts to start. Tom Prince is a Professor of Physics at Caltech and a Senior Research Scientist at NASA’s Jet Propulsion Laboratory. He says, “It’s a bit tricky to observe these restless bodies. First, magnetars don’t last long – just a year to a few years, before colossal waves of x-rays dissipate the magnetic energy. Second, pulsars are really quite old by our standards. One of the most famous pulsars, the crab pulsar for example, exploded in the early 1,000’s. Third, it doesn’t happen often. The last known supernova to explode in our vicinity occurred in 1987 in a satellite Galaxy of the Milky Way.” Prince also notes that while a ground based radio telescope observed the first known radio pulsar/ magnetar transition, it’s been NASA’s orbiting telescopes – Fermi, Swift, RXTE, and NuSTAR, along with the European Space Agency’s XMM-Newton observatory - that have yielded the most interesting data. Observations have included seismic waves rippling through a magnetar, a cloud of high-energy particles called a wind nebula around a magnetar, and a magnetar that is also the slowest spinning neutron star ever detected! Regardless of which came first, the two sides of these stars have much to teach us about matter at the highest densities and the most powerful magnetic fields in the universe.
OTD in Space – February 24: Pulsars First Discovered
On February 24, 1968, an astronomy grad student Jocelyn Bell announced that she had discovered the first pulsar. A few months earlier, she noticed what she called a "bit of scruff" in the data from her telescope. A signal was sending pulses every 1.3 seconds. At first she and her advisor, Anthony Hewish, thought it could have come from aliens. They ruled out that option when they found another signal coming from a different part of the sky. Bell and Hewish found four pulsars before publishing their findings, but they still had no explanation. Scientists have since figured out that pulsars are rapidly spinning neutron stars that radiate narrow beams of light in opposite directions.
We're Turning Pulsars into Galactic GPS!
Scientists have thought for awhile that pulsars could be used as a sort of galactic positioning system, and astronomers have published the most advanced topographical map of Titan to date! ----------
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Mysterious white dwarf pulsar discovered - SpaceTime with Stuart Gary S20E14
Stream Episodes on demand from www.bitesz.com or www.spacetimewithstuartgary.com (both mobile friendly) *Mysterious white dwarf pulsar discovered
Astronomers have discovered their first white dwarf pulsar. These are a stellar class that has been speculated about for over half a century – but never previously detected.
*Space Junk mission failure
An experimental Japanese mission to help clear space junk from low Earth orbit has failed. The plan involved using a 700 metre long electrodynamic tether to slow bits of space junk down causing the refuse to lose altitude and begin the process of re-entering Earth’s atmosphere.
*Juno’s planned orbital changes dropped
NASA Juno mission will now remain in its existing 53 Earth day orbit around the planet Jupiter -- rather that moving to a lower 14 Earth day orbit as planned. The decision follows problems with two helium check valves on the spacecraft main propulsion system.
*Falcon 9 launch from historic pad
A SpaceX Falcon 9 rocket has made history blasting off from Launch Complex 39A at NASA's Kennedy Space Center in Florida. That’s the same launch pad previously used by the mighty Saturn V Apollo moon rocket and the space shuttle fleet. For Enhanced Show Notes, including photos to accompany this episode: http://www.bitesz.com/spacetime-show-notes Subscribe, rate and review SpaceTime at all good podcasting apps…including iTunes, audioBoom, Stitcher, Pocketcasts, Podbean, Radio Public, Tunein Radio, google play, etc. RSS feed: https://audioboom.com/channels/4642443.rss NEW: The SpaceTime with Stuart Gary merchandise shop. Get your T-Shirts, Coffee Cups, badges, tote bag + more and help support the show. Check out the range: http://www.cafepress.com/spacetime Thank you. NEW: Help support SpaceTime and get a free audio book of your choice, plus 30 days free access from audible.com. Just visit www.audibletrial.com/spacetime or click on the banner link at www.spacetimewithstuartgary.com Email: [email protected]
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The Lifetime of a Pulsar: Victoria Kaspi at Perimeter Institute
Victoria Kaspi (McGill University) explains the lifespan of neutron stars during her 2016 public lectures at Perimeter Institute, "The Cosmic Gift of Neutron Stars." Watch the full talk: https://youtu.be/6UG9hoeLcHo
Watch more Perimeter public lectures: https://insidetheperimeter.ca/discover/public-lectures/
A Tour of PSR B1259-63/LS 2883
A fast-moving pulsar appears to have punched a hole in a disk of gas around its companion star and launched a fragment of the disk outward at a speed of about 4 million miles per hour.
Geminga - B0355+54
NASA's Chandra X-ray Observatory has taken deep exposures of two nearby energetic pulsars flying through the Milky Way galaxy. The shape of their X-ray emission suggests there is a geometrical explanation for puzzling differences in behavior shown by some pulsars. Pulsars - rapidly rotating, highly magnetized, neutron stars born in supernova explosions triggered by the collapse of massive stars- were discovered 50 years ago via their pulsed, highly regular, radio emission. Pulsars produce a lighthouse-like beam of radiation that astronomers detect as pulses as the pulsar's rotation sweeps the beam across the sky. Since their discovery, thousands of pulsars have been discovered, many of which produce beams of radio waves and gamma rays. Some pulsars show only radio pulses and others show only gamma-ray pulses. Chandra observations have revealed steady X-ray emission from extensive clouds of high-energy particles, called pulsar wind nebulas, associated with both types of pulsars. New Chandra data on pulsar wind nebulas may explain the presence or absence of radio and gamma-ray pulses. The four-panel graphic shows the two pulsars observed by Chandra. Geminga is in the upper left and B0355+54 is in the upper right. In both of these images, Chandra's X-rays, colored blue and purple, are combined with infrared data from NASA's Spitzer Space Telescope that shows stars in the field of view. Below each data image, an artist's illustration depicts more details of what astronomers think the structure of each pulsar wind nebula looks like. For Geminga, a deep Chandra observation totaling nearly eight days over several years was analyzed to show sweeping, arced trails spanning half a light year and a narrow structure directly behind the pulsar. A five-day Chandra observation of the second pulsar, B0355+54, showed a cap of emission followed by a narrow double trail extending almost five light years. The underlying pulsars are quite similar, both rotating about five times per second and both aged about half a million years. However, Geminga shows gamma-ray pulses with no bright radio emission, while B0355+54 is one of the brightest radio pulsars known yet not seen in gamma rays. A likely interpretation of the Chandra images is that the long narrow trails to the side of Geminga and the double tail of B0355+54 represent narrow jets emanating from the pulsar's spin poles. Both pulsars also contain a torus, a disk-shaped region of emission spreading from the pulsar's spin equator. These donut-shaped structures and jets are crushed and swept back as the pulsars fly through the Galaxy at supersonic speeds. In the case of Geminga, the view of the torus is close to edge-on, while the jets point out to the sides. B0355+54 has a similar structure, but with the torus viewed nearly face-on and the jets pointing nearly directly towards and away from Earth. In B0355+54, the swept-back jets appear to lie almost on top of each other, giving a doubled tail. Both pulsars have magnetic poles quite close to their spin poles, as is the case for the Earth's magnetic field. These magnetic poles are the site of pulsar radio emission so astronomers expect the radio beams to point in a similar direction as the jets. By contrast the gamma-ray emission is mainly produced along the spin equator and so aligns with the torus. For Geminga, astronomers view the bright gamma-ray pulses along the edge of the torus, but the radio beams near the jets point off to the sides and remain unseen. For B0355+54, a jet points almost along our line of sight towards the pulsar. This means astronomers see the bright radio pulses, while the torus and its associated gamma-ray emission are directed in a perpendicular direction to our line of sight, missing the Earth. These two deep Chandra images have, therefore, exposed the spin orientation of these pulsars, helping to explain the presence, and absence, of the radio and gamma-ray pulses.
Imaging X-ray Polarimetry Explorer
NASA has selected a science mission that will allow astronomers to explore, for the first time, the hidden details of some of the most extreme and exotic astronomical objects, such as stellar and supermassive black holes, neutron stars and pulsars. Objects such as black holes can heat surrounding gases to more than a million degrees. The high-energy X-ray radiation from this gas can be polarized – vibrating in a particular direction. The Imaging X-ray Polarimetry Explorer (IXPE) mission will fly three space telescopes with cameras capable of measuring the polarization of these cosmic X-rays, allowing scientists to answer fundamental questions about these turbulent and extreme environments where gravitational, electric and magnetic fields are at their limits.
Fermi Finds First Extragalactic Gamma Ray Pulsar
Researchers using NASA's Fermi Gamma-ray Space Telescope have discovered the first gamma-ray pulsar in a galaxy other than our own. The object sets a new record for the most luminous gamma-ray pulsar known. The pulsar lies in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a small galaxy that orbits our Milky Way and is located 163,000 light-years away. The Tarantula Nebula is the largest, most active and most complex star-formation region in our galactic neighborhood. It was identified as a bright source of gamma rays, the highest-energy form of light, early in the Fermi mission. Astronomers initially attributed this glow to collisions of subatomic particles accelerated in the shock waves produced by supernova . However, the discovery of gamma-ray pulses from a previously known pulsar named PSR J0540-6919 shows that it is responsible for roughly half of the gamma-ray brightness previously thought to come from the nebula. Gamma-ray pulses from J0540-6919 have 20 times the intensity of the previous record-holder, the pulsar in the famous Crab Nebula. Yet they have roughly similar levels of radio, optical and X-ray emission. Accounting for these differences will guide astronomers to a better understanding of the extreme physics at work in young pulsars. Learn more about Pulsars at http://www.spacetv.net/pulsars/
Learn more about Neutron Stars at http://www.spacetv.net/neutron-stars/
Learn more about Stars at http://www.spacetv.net/stars/ Credit: NASA's Goddard Space Flight Center
Fermi Space Telescope Catches a 'Transformer' Pulsar
In late June 2013, an exceptional binary system containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed. The pulsar's radio beacon vanished, while at the same time the system brightened fivefold in gamma rays, the most powerful form of light, according to measurements by NASA's Fermi Gamma-ray Space Telescope. The system, known as AY Sextantis, is located about 4,400 light-years away in the constellation Sextans. It pairs a 1.7-millisecond pulsar named PSR J1023+0038 -- J1023 for short -- with a star containing about one-fifth the mass of the sun. The stars complete an orbit in only 4.8 hours, which places them so close together that the pulsar will gradually evaporate its companion. To better understand J1023's spin and orbital evolution, the system was routinely monitored in radio. These observations revealed that the pulsar's radio signal had turned off and prompted the search for an associated change in its gamma-ray properties. What's happening, astronomers say, are the last sputtering throes of the pulsar spin-up process. Researchers regard the system as a unique laboratory for understanding how millisecond pulsars form and for studying details of how accretion takes place on neutron stars. In J1023, the stars are close enough that a stream of gas flows from the sun-like star toward the pulsar. The pulsar's rapid rotation and intense magnetic field are responsible for both the radio beam and its powerful pulsar wind. When the radio beam is detectable, the pulsar wind holds back the companion's gas stream, preventing it from approaching too closely. But now and then the stream surges, pushing its way closer to the pulsar and establishing an accretion disk. When gas from the disk falls to an altitude of about 50 miles (80 km), processes involved in creating the radio beam are either shut down or, more likely, obscured. Some of the gas may be accelerated outward at nearly the speed of light, forming dual particle jets firing in opposite directions. Shock waves within and along the periphery of these jets are a likely source of the bright gamma-ray emission detected by Fermi. Read more at: http://www.nasa.gov/content/goddard/n... This video is public domain and can be downloaded at: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11609 Subscribe for more Space wonders on ΥουΤυbe: https://tinyurl.com/SpaceTelescopesYouTube
Classroom Aid - Hulse-Taylor Pulsar PSR B1913+16
Text http://howfarawayisit.com/wp-content/uploads/2013/05/Gravitational-Waves.pdf Credits http://howfarawayisit.com/wp-content/uploads/2013/05/Credits-and-Research.pdf
Less Than Five - What is a Pulsar?
Pulsars are an exotic astronomical object left over from exploding stars. Mysterious as they may be, science has helped us to reveal several facts about these cosmological rogues.