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A new study of two supernova remnants, the debris left behind after stars explode, suggests the explosions came from stellar siblings that once orbited each other. The first star\u2019s detonation sent its binary companion hurtling through space, and then, after traveling for thousands of years, the surviving star blew up too.<\/p>\n
\u201cUsing 16 years of data from NASA\u2019s Fermi Gamma-ray Space Telescope<\/a>, our analysis uncovered gamma rays associated with a supernova remnant that was hidden in the glare of its neighbor, the Jellyfish Nebula, one of the brightest gamma-ray-emitting supernova remnants known,” said Miltiadis Michailidis, a postdoctoral fellow in the physics department at Stanford University<\/a> in California. \u201cThere are so many striking connections between the two remnants that we conclude they\u2019re likely related, giving us the first known example of a binary system where both stars have undergone supernova explosions.\u201d<\/p>\n Michailidis presented the findings Wednesday at the 248th meeting of the American Astronomical Society<\/a> in Pasadena, California. A paper describing the results will appear in a future edition of Nature Communications.<\/p>\n The study focused on a faint supernova remnant called G189.6+3.3, which is mainly visible in X-rays. It is upstaged by its brighter and better-known neighbor, the Jellyfish Nebula<\/a> (IC 443). The two star wrecks, both located in the constellation Gemini, appear to partially overlap as seen in X-rays. Recent X-ray evidence suggests that hot plasma likely associated with G189.6+3.3 may extend across the entire region, a hint that the overlap may be nearly total.<\/p>\n A massive star explodes when its energy-producing core runs out of fuel and collapses under its own weight, triggering an explosion that blows the star apart. The explosion\u2019s shock wave encloses a hot cloud of debris that rapidly expands into space. So far, astronomers have cataloged about 300 supernova remnants in our galaxy. \u00a0<\/p>\n The Fermi mission is part of NASA\u2019s fleet of observatories monitoring the changing cosmos to help humanity better understand how the universe works. More than a decade ago, observations from Fermi\u2019s LAT (Large Area Telescope) showed that the shock waves of supernova remnants accelerated particles to within a fraction of the speed of light, a process first proposed by physicist Enrico Fermi<\/a> \u2014 the mission\u2019s namesake \u2014 in 1949.<\/p>\n These high-speed particles, called cosmic rays, interact with interstellar gas to produce gamma rays, the highest-energy form of light. Protons make up 99% of cosmic ray particles. To prove that accelerated protons are responsible for the glow, astronomers search for a specific gamma-ray feature. When cosmic-ray protons smash into interstellar gas, they produce a short-lived particle called a neutral pion, which almost immediately decays into a pair of gamma rays. This emission occurs within a specific band of energies associated with the neutral pion\u2019s mass and lies within the range detected by Fermi\u2019s LAT instrument.<\/p>\n In 2013, Fermi observations proved that the Jellyfish Nebula, which is interacting with part of a glowing cloud of hydrogen gas known as Sharpless 249, produced gamma rays through this mechanism.<\/a> Its neighbor, G189.6+3.3, was discovered in 1994 as part of an X-ray survey by the German-led ROSAT<\/a> (Roentgen Satellite) mission.<\/p>\n A bright filament of gas lies between the overlapping remnants. New observations of this feature reveal that the shock wave from G189.6+3.3 slammed into dense interstellar gas there and dramatically slowed, key evidence that both remnants are interacting with the same cloud system.<\/p>\n Astronomers think the Jellyfish Nebula is also a candidate PeVatron<\/a>, a cosmic particle accelerator capable of boosting protons to energies so high they could nearly escape our galaxy. Such particles can produce gamma rays with trillions of times more energy than visible light. Finding a second particle accelerator near the Jellyfish Nebula could offer scientists new clues for how supernova remnants develop into PeVatrons.<\/p>\n \u201cThe overlapping remnants, a connecting gas filament, and the availability of data from Fermi and other facilities motivated us to delve into this complex but little-studied region,\u201d said co-author Marianne Lemoine-Goumard, an astrophysicist at the French\u00a0National Centre for Scientific Research<\/a>\u00a0(CNRS) based at the\u00a0University of Bordeaux<\/a>. \u201cWith Fermi\u2019s LAT instrument, we found gamma-ray emission associated with accelerated protons in the northern part of the fainter remnant. If both remnants are interacting with the same structure, then they must share a common distance from us.\u201d<\/p>\n The team concludes the remnants lie about 6,000 light-years away, their explosion centers are separated by roughly 40 light-years projected onto the plane of the sky, and the original stars may have been 20 or more times the Sun\u2019s mass.<\/p>\n Estimates of the remnants\u2019 ages vary widely, but the team concludes that the age of the Jellyfish Nebula is 8,000 to 9,000 years, while G189.6+3.3 is between 20,000 to 110,000 years old. This means the delay between the explosions could have extended for up to 100,000 years.<\/p>\n In addition, the team conducted computer simulations of a million massive binary systems. They show that systems where the stars orbit close enough to exchange matter and interact during their lives can readily produce dual supernova explosions with similar separations and time delays as those found for the remnants. The team also estimated that the chance of randomly encountering this combination of observed spatial alignment and compatible distances to be less than 1%, strongly supporting a physical association.<\/p>\n \u201cThe evidence we\u2019ve compiled \u2014 including observations across the spectrum, the chemical and physical properties of the remnants, simulations, and more \u2014 paints a compelling picture of a dual supernova event,\u201d said Michailidis.<\/p>\n This study identifies a unique possible example of a binary system where both stars exploded as supernovae and left behind separate, detectable supernova remnants. Astronomers think that most massive stars form in binary or multiple-star systems. The Jellyfish Nebula\/G189.6+3.3 complex offers astronomers a rare opportunity to study how massive binary stars evolve, exchange matter, explode, and experience velocity changes \u2014 called kicks \u2014 induced by the supernova blast. It also provides a powerful new laboratory for understanding how coupled supernova remnants behave, including how they accelerate particles, generate gamma rays, and shape their surrounding environments.<\/p>\n \u201cFermi\u2019s gamma-ray observations of supernova remnants continue to reveal the dynamic lives of stars,\u201d said Elizabeth Hays, the Fermi project scientist at NASA\u2019s Goddard Space Flight Center<\/a> in Greenbelt, Maryland.\u00a0\u201cWe can now connect the glowing remains of two massive stars to a powerful pair that evolved together over thousands of years.\u201d<\/p>\n By Francis Reddy<\/a> Media Contact:
NASA\u2019s Goddard Space Flight Center<\/a>, Greenbelt, Md.<\/strong><\/p>\n
Claire Andreoli<\/a>
301-286-1940
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.<\/p>\n<\/div>\n