What Is A Magnetar?
What is a Magnetar?
A magnetar is a type of neutron star with an extremely powerful magnetic field, the decay of which powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.1
History
On March 5, 1979, several months after dropping probes into the toxic atmosphere of Venus, two Soviet spacecraft, Venera 11 and 12, were drifting through the inner solar system on an elliptical orbit. It had been an uneventful cruise. The radiation readings on board both probes hovered around a nominal 100 counts per second. But at 10:51AM EST, a pulse of gamma radiation hit them. Within a fraction of a millisecond, the radiation level shot above 200,000 counts per second and quickly went off scale.
Eleven seconds later gamma rays swamped the NASA space probe Helios 2, also orbiting the sun. A plane wave front of high-energy radiation was evidently sweeping through the solar system. It soon reached Venus and saturated the Pioneer Venus Orbiter’s detector. Within seconds the gamma rays reached Earth. They flooded detectors on three U.S. Department of Defense Vela satellites, the Soviet Prognoz 7 satellite, and the Einstein Observatory. Finally, on its way out of the solar system, the wave also blitzed the International Sun-Earth Explorer.
The pulse of highly energetic, or “hard,” gamma rays was 100 times as intense as any previous burst of gamma rays detected from beyond the solar system, and it lasted just two tenths of a second. At the time, nobody noticed; life continued calmly beneath our planet’s protective atmosphere. Fortunately, all 10 spacecraft survived the trauma without permanent damage. The hard pulse was followed by a fainter glow of lower-energy, or “soft,” gamma rays, as well as x-rays, which steadily faded over the subsequent three minutes. As it faded away, the signal oscillated gently, with a period of eight seconds. Fourteen and a half hours later, at 1:17AM on March 6, another, fainter burst of x-rays came from the same spot on the sky. Over the ensuing four years, Evgeny P. Mazets of the Ioffe Institute in St. Petersburg, Russia, and his collaborators detected 16 bursts coming from the same direction. They varied in intensity, but all were fainter and shorter than the March 5 burst.
Astronomers had never seen anything like this. For want of a better idea, they initially listed these bursts in catalogues alongside the better-known gamma-ray bursts (GRBs), even though they clearly differed in several ways. In the mid-1980s Kevin C. Hurley of the University of California at Berkeley realized that similar outbursts were coming from two other areas of the sky. Evidently these sources were all repeating unlike GRBs, which are one-shot events [see “The Brightest Explosions in the Universe,” by Neil Gehrels, Luigi Piro and Peter J. T. Leonard; Scientific American, December 2002]. At a July 1986 meeting in Toulouse, France, astronomers agreed on the approximate locations of the three sources and dubbed them “soft gamma repeaters” (SGRs). The alphabet soup of astronomy had gained a new ingredient.
Another seven years passed before two of us (Duncan and Thompson) devised an explanation for these strange objects, and only in 1998 did one of us (Kouveliotou) and her team find remains of a star that exploded 5,000 years ago. Unless this overlap was pure coincidence, it put the source 1,000 times as far away as theorists had thought—and thus made it a million times brighter than the Eddington limit. In 0.2 second the March 1979 event released as much energy as the sun radiates in roughly 10,000 years, and it concentrated that energy in gamma rays rather than spreading it across the electromagnetic spectrum.2
About 26 magnetars are known (see here).
1 http://en.wikipedia.org/wiki/Magnetar
2 http://solomon.as.utexas.edu/~duncan/sciam.pdf
More Posts from Fillthevoid-with-space and Others
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gas cloud get squished (gravitational collapse) then sometimes smaller elements can squish together to make bigger elements (nuclear fusion) and this continues as long as the smolest elements (hydrogen and helium) are in the core
What is an upcoming project/mission you're most excited for?
It is likely that I’ll be assigned a mission to the International Space Station (ISS) within the next few years. We’ve had a continuous presence on the Space Station for 17 years now, along with our international partners (Russian Space Agency, European Space Agency, Japanese Space Agency, and Canadian Space Agency). Missions on the ISS typically last 6 months. I’m incredibly excited to contribute to the impressive array of scientific experiments that we are conducting every day on ISS (I am a scientist after all!), and very much look forward to the potential of going for a spacewalk and gaining that perspective of gazing down on the fragile blue ball that is our home from above. Beyond that, being part of test missions on the Orion spacecraft (currently under construction at NASA!) would be an extraordinary opportunity. The current NASA plan is to send astronauts in Orion in a mission that will go 40,000 miles beyond the Moon in the early 2020s, reaching a distance further than that ever travelled by humans. I’d certainly be game for that!
In the ancient world (and, honestly, today too) there’s nothing spookier than the sky doing something weird. Auroras, meteors, comets, and eclipses all fell under the category of scary, prophetic bad omens, but don’t worry! In this podcast I explain what they are! There are also some opportunities to see these astronomical events in action coming up. The annual Perseid meteor shower reaches its peak August 11-13 and there will be a total eclipse of the Sun (or a partial eclipse, depending where you’re viewing it from) across North America on August 21, 2017.
Below the cut are sources, music credits, vocabulary list, and the transcript of this episode. Check out the glossary, it’s a big one! There are also some cool eclipse-viewing resources I’ll highlight so you can view this phenomenon safely.
Let me know what you think I should research by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me in real life. And please check out the podcast on iTunes, rate it or review it if you’d like, subscribe, and maybe tell your friends about it if you think they’d like to listen!
(My thoughts on the next episode were spectroscopy, probes through the ages, and the transit of Venus. Let me know by the 2nd and I’ll have the next podcast up on August 14th, barring any delays due to trip fatigue!)
Glossary
auroras - a light display that occurs when a magnetosphere is sufficiently disturbed by solar wind that charged particles scatter into the upper atmosphere and lose their energy.
comet - a small, icy body that orbits the Sun. When its orbit takes it close to the Sun, the comet warms up and releases gases and debris that produce a visible atmosphere, sometimes called the comet’s tail.
corona - the hot outer atmosphere of the Sun.
eclipse - when three celestial bodies line up so that one obstructs the visibility of the other two. A solar eclipse can be partial (only part of the Sun is obscured by the Moon), total (all of the Sun is hidden by the Moon), or annular ( the Moon is close to Earth and appears too small to completely cover the Sun completely).
Exeligmos cycle - a cycle that is 3 times the saros cycle, or 669 months. It is more accurate means of predicting eclipses and additionally predicts eclipses that will be visible from a location close to the initial eclipse.
Inex cycle - a cycle of 28 years and 345 days long used to predict an eclipse that’s visible in the opposite hemisphere. For example, if an eclipse happens in the Northern hemisphere, one Inex cycle later there will be an eclipse visible in the Southern hemisphere. The Inex cycle does not ensure that both kinds of eclipses will be of the same type.
meteor - a small rocky or metallic body in space, smaller than asteroids. Contact with the Earth’s atmosphere causes a meteor to burn up in a streak of light. Many meteors entering the atmosphere within a few minutes of each other is called a meteor shower. If a meteor impacts on Earth’s surface without burning up, it is then classified as a meteorite.
penumbra - a region where only a portion of the light source is obscured. When the light source is completely blocked, this darkest part of a shadow is called the umbra.
perihelion - an object’s closest approach to the Sun in its orbit. Its greatest distance from the Sun is called its aphelion.
perigee - a satellite’s closest approach to the Earth in its orbit. Its greatest distance from Earth is called its apogee.
radiant - the point in the sky where objects appear to come from. For example, the Perseid meteor shower appears to come from the constellation Perseus.
Saros cycle - a cycle of 223 months that is used to predict eclipses.
solar prominence - a large, bright feature anchored to the Sun's surface and extend outwards into the Sun's corona. A prominence forms in about a day out of plasma, a hot gas made of electrically charged hydrogen and helium. Stable prominences may last for several months, looping hundreds of thousands of miles into space as plasma flows along a structure of the Sun’s magnetic field that has burst outward, releasing the plasma.
syzygy - the straight-line alignment of three celestial bodies.
Script/Transcript
Sources
Perseids via EarthSky
Perseids via NASA
Meteor showers and viewing tips via StarDate
Comet Swift-Tuttle via NASA
My local library’s information and recommended reading list for learning about eclipses. Love you, Multnomah County!
Map of the Path of Totality across the United States
Solar eclipse map and calendar via the Exploratorium website
Free eclipse glasses at libraries via Lunar and Planetary Institute
Guide to making a pinhole camera to view the eclipse via NASA
Historical eclipses via NASA
Historical eclipses via Astronomy Magazine
“Even if the Moon, however, does sometimes cover the Sun entirely, the eclipse does not have duration or extension; but a kind of light is visible about the rim which keeps the shadow from being profound and absolute.”
Solar prominence via NASA
Solar flares via NASA
Fred Espenak’s guide to eclipses. He’s a former NASA astrophysicist who’s credited with all the eclipse predictions so I trust him.
Some good but confusing charts on solar eclipse Saros cycles via NASA
“Van den Bergh placed all 8,000 solar eclipses in von Oppolzer's Canon der Finsternisse (1887) into a large two-dimensional matrix. Each Saros series was arranged as a separate column containing every eclipse in chronological order. The individual Saros columns were then staggered so that the horizontal rows each corresponded to different Inex series.”
A Danish webpage on calculating eclipses
Hawks, Ellison. The Boy’s Book of Astronomy. Frederick A. Stokes Co: New York, 1914. Located in Google Books preview. (Heads up, this is a fairly racist source.)
Richard Cohen. Chasing the Sun. Random House: NY, 2010.
Robert A. Henning: “different forms, wavering, many colours diffusing and changing, sometimes far away, sometimes filling the heavens around and above, plunging great dropping spears and sheets of colour earthward towards your very head as though a great hand were dropping colour like burning oil” (43).
Ernest W. Hawkes: “whistling, crackling noise” (44).
Jeremy Belknap: “like running one’s thumb and forefinger down a silk scarf” (44).
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘Eclippse’ by Radical Face off his album Sunn Moonn Eclippse. Check out the video in the album link, it’s amazing.
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
Hubble Showcases a Remarkable Galactic Hybrid : UGC 12591s classification straddles somewhere between a lenticular and a spiral galaxy. It lies just under 400 million light-years from us in the PiscesPerseus Supercluster.
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Where to look, and when.
New Zealand was lovely, but I already touched on what I’d be tempted to talk about with my Southern Stars episode. A person I interviewed as a potential new housemate gave me the idea for this episode because the joy of outer space is truly everywhere and anywhere. The field of astrogeology was not something I had heard of before, though I had indirectly heard of Eugene Shoemaker. I knew the comet Shoemaker-Levy 9 was named after him (and Carolyn Shoemaker, his wife). It turns out he basically founded the modern field of astrogeology! So I talk about him for quite a while, too.
Below the cut are the glossary, transcript, sources, and music credits. Send me any topic suggestions via Tumblr message (you don’t need an account to do this, just submit as anonymous). You can also tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me in real life. Subscribe on iTunes to get the new episodes of my semi-monthly podcast, and please please please rate and review it. Go ahead and tell friends if you think they’d like to hear it, too!
(The next episode is going to be famous comets, and I’m shooting for an April release.)
Glossary
aeolian processes - the wind’s ability to shape the surface of a planet by eroding, transporting, and depositing materials. Most effective in desert regions, where the sparse vegetation, dry soil, and loose sediments mean these processes have the greatest impact.
albedo features - the International Astronomical Union term for an area of a planet that has a high contrast in color with the surrounding area on a planet’s surface.
chaos terrain - the International Astronomical Union term for where ridges, cracks, and plains on a planet’s surface appear broken and smashed up against each other.
chasma - the International Astronomical Union term for a long, steep-sided, deep surface indentation in a planet’s surface.
colles - the International Astronomical Union term for collections of small, knob-like hills on the surface of a planet.
dorsum - the International Astronomical Union term for a wrinkle-like ridge on a planet’s surface.
facula - the International Astronomical Union term for a bright spot on planets or moons.
fluvial processes - the ways in which rivers and streams impact a planet’s surface by eroding or creating deposits and landforms out of sediment. Sometimes, streams or rivers are associated with glaciers, ice sheets, or ice caps, and then they are called glaciofluvial or fluvioglacial processes.
fossa - the International Astronomical Union term for a long, narrow depression in a planet’s surface.
lacunae - the International Astronomical Union term for irregularly shaped depressions that look like dry lake beds on the surface of Saturn’s moon, Titan.
lobate scarp - the International Astronomical Union term for a curved slope that is probably formed by compressive tectonic movement.
mare - the International Astronomical Union term for a large, circular plain on a planet’s surface.
terra - the International Astronomical Union term for an extensive landmass like a plain or highland.
tesserae - the International Astronomical Union term for regions on the planet Venus that are tiled, polygonal shapes.
vallis - the International Astronomical Union term for a valley on the surface of a planet.
Script/Transcript
Sources
Planetary geology via Wikipedia
Lunar Lobate Scarp via the Lunar Reconnaissance Orbiter Camera
Eugene M. Shoemaker Biographical Memoirs via NASA
Dr. Eugene Shoemaker, 69; Set Record for Finding Comets via The New York Times (July 1997)
Eugene Shoemaker (1928-1997) via NASA Jet Propulsion Lab
Eugene Shoemaker (1928 - 1997) via American Astronomical Society
Gene Shoemaker - Founder of Astrogeology via US Geological Society
Eugene Shoemaker via the Planetary Society
Eugene Shoemaker Ashes Carried on Lunar Prospector via NASA Jet Propulsion Lab
Eugene M. Shoemaker and the Integration of Earth and Sky via GSA Today (April 2001)
Destination Moon by Carolyn C. Porco (Feb 2000)
“I wanted to include something to commemorate Gene’s scientific legacy. It seemed appropriate to choose his favorite photo of Meteor Crater and a photo of the last comet that he and his wife saw together, Comet Hale-Bopp. And somehow, I extracted from the dusty realm of dim memory a passage I had read from Romeo and Juliet long ago that seemed perfect for the occasion.”
Who is an Astrogeologist? via Space Awareness
Careers via the USGS Astrogeology Science Center
“Public Service by contributing to the public knowledge about our Solar System.”
Lunar Calibration via USGS
“The unmatched stability of the lunar surface reflectance (better than one part in 108 per year) makes the Moon attractive as a calibration light source; its radiance can be known with high precision and accuracy. The lunar irradiance is similar in brightness to sunlit land masses on the Earth.”
Video: Astrogeology 1963-2013: Fifty Years of Exploration via the USGS Astrogeology Science Center
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘Muddy Waters’ by LP off her album Lost On You
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
Did you know that some observatories are not on the ground and not orbiting Earth, but are mounted on airplanes? I finally researched SOFIA, an infrared observatory in a repurposed plane, and discovered there’s a rich history of airborne astronomy. And by airborne astronomy, I mean a lot of people took pictures of astronomical phenomena from planes!
Below the cut, I have the glossary, transcript, sources, and music credits. If you have suggestions for topics I could cover, please send me a Tumblr message or tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Please subscribe on iTunes, rate my podcast and maybe review it, and tell friends if you think they’d like to hear it!
(My thoughts on the next episode are Chuck Yeager, Stephen Hawking and his theories, the opposition of Mars, famous comets, recent developments and discoveries in the astronomer community, or an atmospheric phenomenon called ‘Steve.’ The next episode will go up April 30th, lord willing and the creek don’t rise!)
Glossary
absorption bands - the areas of the electromagnetic spectrum that are absorbed by atmospheric gases.
atmospheric windows - the areas of the electromagnetic spectrum where the atmosphere is transparent, or does not absorb the radiation of specific wavelengths.
corona - the hot outer atmosphere of the Sun.
electromagnetic spectrum - the range of wavelengths or frequencies over which electromagnetic radiation extends. A photon transmits electromagnetic radiation at different frequencies, which are in a range that includes (from highest frequency to lowest) gamma rays, X-rays, ultraviolet light, visible light, infrared, microwaves, and radio waves
frequency - the number of times a wave oscillates up and down per second.
hypoxia - insufficient oxygen in the blood. Symptoms include vertigo, nausea, weakness, hyperventilation, slowed thinking, poor coordination, dimmed vision, and increased heart rate.
photon - a type of elementary particle that moves in a wave. It transmits electromagnetic radition such as light. The more energy a photon has, the higher its frequency.
Script/Transcript
Sources
A map of every active satellite orbiting Earth via Quartz
Infrared radiation via Gemini Observatory (Feb 1999)
Absorption Bands and Atmospheric Windows via NASA
Gladys Ingle of the 13 BLACK CATS changes planes in mid-air via YouTube
Milestones in Airborne Astronomy: From the 1920's to the Present by Wendy Whiting Dolci (1997)
Limits to human performance: elevated risks on high mountains, by Huey, Raymond B. and Xavier Eguskitza. Journal of Experimental Biology (2001)
When Humans Fly High by Linda Pendleton (Nov 1999)
Dalton's Law tells us that the total pressure of any mixture of gases (with constant temperature and volume) is the sum of the individual pressures (also called partial pressure) of each gas in the mixture. Also, partial pressure of each gas is proportional to that gas's percentage of the total mixture. Because the percentage of oxygen in the atmosphere remains constant at 21%, Dalton's Law lets us calculate the partial pressure of the oxygen in the atmosphere at any altitude. As we'll see shortly, the human body is affected by the pressure of the gases in the atmosphere. The partial pressure of oxygen (and to a lesser extent other gases) available in the surrounding air is important in determining the onset and severity of hypoxia.
Henry's Law states that the amount of gas dissolved in a solution is proportional to the partial pressure of the gas over the solution. A bottle of carbonated liquid demonstrates Henry's Law. When the bottle is uncapped, the carbon dioxide (CO2) in the mixture will slowly diffuse to the atmosphere until the pressure of CO2 in the liquid equals the pressure of CO2 in the surrounding air. The soda will then be "flat." A bottle of soda opened in an unpressurized aircraft at 10,000 feet will foam and overflow. The opposite will happen with soda opened at pressures greater than one atmosphere. A champagne cork won't pop in a diving bathysphere pressurized for deep ocean exploration.
Boyle's Law states that the volume of a gas is inversely proportional to the pressure on the gas as long as the temperature remains constant. A gas will expand when the pressure on it is decreased. This law holds true for all gases, even those trapped in body cavities. A volume of gas at sea level pressure will expand to approximately twice its original volume at 18,000 feet, nearly nine times its original volume at 50,000 feet.
Graham's Law tells us that a gas at higher pressure exerts a force toward a region of lower pressure. There's a permeable or semi-permeable membrane separating the gases, and gas will diffuse across the membrane from the higher pressure to the lower pressure. This will continue until the pressure of the gas is equal, or nearly equal, on both sides of the membrane. Graham's Law is true for all gases and each gas in a mixture behaves independently. It's possible to have two or more gases in a solution diffusing in opposite directions across the same membrane and, in fact, this is what happens to make oxygen transfer possible in the cells and tissues of the human body.
High-Altitude Hypoxia via Harvard (July 2012)
Kuiper Airborne Observatory via NASA (May 2005)
NASA's Kuiper Airborne Observatory via YouTube
SOFIA Science Center
Up all Night with SOFIA, NASA's Flying Observatory via YouTube
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘A Bite Out of My Bed’ by The New Pornographers off their album Together.
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
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A podcast project to fill the space in my heart and my time that used to be filled with academic research. In 2018, that space gets filled with... MORE SPACE! Cheerfully researched, painstakingly edited, informal as hell, definitely worth everyone's time.
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