💥 Kilonova: The ⭐ collision that unlocked the secrets of the universe

[Quartz Obsession] Kilonova October 16, 2017 Big news --------------------------------------------------------------- Astronomers just announced the first observation of one of the most epic events in the universe: The [violent merger of two collapsed stars](. Neutron stars have just a bit more mass than our sun, but they’re compressed into a ball the width of a mid-sized city (15 km or 9 miles). A teaspoon of neutron star weighs 10 billion kg (22 billion lb)—[roughly the same as the entirety of Mt. Everest](. About 130 million years ago, two of these collapsed stars smashed into each other—a phenomenon known as a kilonova. Fast forward to August 17, when the gravitational waves from the event reached Earth and were picked up by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Over the next few days, hundreds of scientists witnessed an unimaginably massive collision—one that ejected at least 40 times the Earth’s mass in solid gold. Today, they shared their findings—and their otherworldly experiences—with the public. [Watch NASA's animation of the event]( explainer What did scientists actually see? --------------------------------------------------------------- LIGO has two detectors: one each in Livingston, Louisiana and Hanford, Washington (there is also a sister installation, Virgo, in Italy). Each detector consists of two 4-km tunnels, built at right angles, and emptied of all air. A laser beam is split in two, and each beam is sent down one tunnel and reflected back, where they are recombined. [giphy-downsized-large (5)] Gravitational waves stretch and then contract spacetime as they pass, just as ripples on a pond move the surface up and then down. As the waves from the neutron star collision passed through the lasers, they changed—ever so slightly—the times it took each laser to travel those four kilometers. The distortion would only be as wide as a fraction of the width of a single atom. But that was enough for scientists to take note of a truly astronomical event in the making. The timing couldn’t have been better: It’s only been about two years since LIGO went online, and only two weeks since its principal scientists won the Nobel Prize for physics. timeline How it went down --------------------------------------------------------------- 130 million years ago: Two neutron stars collide. September 2015: LIGO observatories make the very first observation of gravitational waves—from the merger of a pair of black holes. Aug. 17, 8:41 am ET: A gravitational wave hits the Virgo detector; 22 milliseconds later it hits Livingston; 3 ms after that it hits Hanford. The waves continue for about 100 seconds. 1.7 seconds after the gravitational waves hit Earth, the orbiting Fermi telescope registers a burst of gamma radiation from the Hydra constellation. 9:21 am ET: Alerts start lighting up the inboxes and smartphones of hundreds of astronomers around the world. 1:51 pm ET: The LIGO-Virgo team directs hundreds of telescopes to scrutinize the skies near Hydra. Aug. 18: News of the cataclysmic collision quickly [began to leak on Twitter]( from excited scientists (“Tonight is one of those nights where watching the astronomical observations roll in is better than any story any human has ever told,” [one wrote]( but the news was not confirmed until today. Which of these cosmic events cannot produce new elements? Solar eclipseBig BangSupernovaeMerging neutron stars Correct. Incorrect. If your inbox doesn’t support this quiz, find the solution at bottom of email. Bloop! The chirp --------------------------------------------------------------- The Hanford signal, translated into sound, was a 100-second chirp “that ended in a sudden whoop to 1,000 cycles per second, two octaves above middle C,” [the New York Times reported.]( Ever since the early telescopes, the science of astronomy has been about collecting visual—or at least electromagnetic—information. It was basically a silent movie, France Córdova, director of the National Science Foundation, which funds LIGO, [explained to the Washington Post:]( The earliest gravitational wave detections added sound, but they were little more than strange noises echoing in the dark, she said. “We couldn’t pinpoint the location of the source.” Now, for the first time, the soundtrack of the cosmos has synced up with what scientists can see. “It’s all the difference in the world.” [Here’s some of the 100 seconds of audio — you can’t really hear much until the 0:50 mark](. elemental Heavy metal --------------------------------------------------------------- Everyone has seen the periodic table, listing all the elements in the known universe. But until today, [we had no proof of where most of the elements came from.]( We find almost all of these elements on Earth—but except for the rarities created in a lab, they didn’t form here. Almost everything on the Earth is borrowed from dust left behind during the formation of the solar system or received in the form of comets and asteroids crashing into the planet. To forge new stable elements, you need extreme amounts of energy that will crush the sub-atomic components of elements—protons, electrons, and neutrons—together in new configurations. Our sun is too small for the kinds of energy needed. [periodic_table_final] Bigger stars and supernovae can create slightly larger elements, with atomic numbers between carbon and zirconium. Scientists have long theorized that these remaining elements are made in even more violent celestial events—and today they got proof. In the days following August 17, researchers watched as the electromagnetic radiation released by the collision shifted from blue to red, as the heat of the explosion faded. By analyzing the spectrum of light emitted, scientists could detect the heavy elements like silver, gold, and uranium that were created by the event. by the digits [3,500:]( number of co-authors on the neutron star collision paper, published in the Astrophysical Journal Letters. That’s close to the record-setting 5,154 authors who used the Large Hadron Collider to estimate the mass of the Higgs boson. [236 sextillion tonnes:]( The minimum amount of pure gold created by the neutron star merger. (That’s 40 times the mass of Earth.) [100 seconds:]( of gravitational waves detected on Earth, by far the longest event ever recorded. watch this! The astrophysicist Brian Greene explains how Einstein predicted gravitational waves and how we measure them today. person of interest One lucky post-grad --------------------------------------------------------------- Ryan Foley, an astronomer at the University of California at Santa Cruz, abandoned his partner at an amusement park when he got a text about the LIGO discovery, jumping his bike and pedaling back to the office.As Foley’s team pored through data from the Swope telescope in Chile, [postdoctoral researcher Charlie Kilpatrick]( spotted a tiny dot beside a galaxy known as NGC 4993. He sent a message to colleagues on Slack: @foley found something sending you a screenshotFoley told the Washington Post that Kilpatrick was incredibly calm given the magnitude of the event: “Charlie is the first person, as far as we know, the first human to have ever seen optical photons from a gravitational wave event,” [he told the Washington Post](. “It’s been sort of slow to dawn on me what a big deal this is,” Kilpatrick told [National Geographic](. talk to us How do you feel about kilonovae now? [Click here to vote]( Humbled by the awesomeness of the universeGonna eat an edible and go to the planetariumAlready trademarked as my new hip-hop MC moniker the fine print In Friday’s poll about [kaleidoscopes]( 47% of you said we could “color you intrigued.” 🌈 Today’s email was written by [Akshat Rathi]( and [Adam Pasick.]( Images: NASA and ESA. NASA’s Goddard Space Flight Center/CI Lab (animation). Reuters/Jonathan Ernst (eclipse). The correct answer to the quiz is Solar eclipse. 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