News / Science News

    Pulse of a Dead Star Powers Intense Gamma Rays

    NASA | OCTOBER 7, 2014

    Our Milky Way galaxy is littered with the still-sizzling remains of exploded stars. When the most massive stars explode as supernovas, they don't fade into the night, but sometimes glow ferociously with high-energy gamma rays. What powers these energetic stellar remains?



    The blue dot in this image marks the spot of an energetic pulsar -- the magnetic, spinning core of star that blew up in a supernova explosion. Image credit: NASA/JPL-Caltech/SAO


    NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, is helping to untangle the mystery. The observatory's high-energy X-ray eyes were able to peer into a particular site of powerful gamma rays and confirm the source: A spinning, dead star called a pulsar. Pulsars are one of several types of stellar remnants that are left over when stars blow up in supernova explosions.

    This is not the first time pulsars have been discovered to be the culprits behind intense gamma rays, but NuSTAR has helped in a case that was tougher to crack due to the distance of the object in question.

    NuSTAR joins NASA's Chandra X-ray Observatory and Fermi Gamma-ray Space Telescope, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia, each with its own unique strengths, to better understand the evolution of these not-so-peaceful dead stars.

    The energy from this corpse of a star is enough to power the gamma-ray luminosity we are seeing. While pulsars are often behind these gamma rays in our galaxy, other sources can be as well, including the outer shells of the supernova remnants, X-ray binary stars and star-formation regions.

    In recent years, the Max-Planck Institute for Astronomy's H.E.S.S. experiment has identified more than 80 incredibly powerful sites of gamma rays, called high-energy gamma-ray sources, in our Milky Way. Most of these have been associated with prior supernova explosions, but for many, the primary source of observed gamma rays remains unknown.

    The gamma-ray source pinpointed in this new study, called HESS J1640-465, is one of the most luminous discovered so far. It was already known to be linked with a supernova remnant, but the source of its power was unclear. While data from Chandra and the European Space Agency's XMM-Newton telescopes hinted that the power source was a pulsar, intervening clouds of gas blocked the view, making it difficult to see.

    NuSTAR complements Chandra and XMM-Newton in its capability to detect higher-energy range of X-rays that can, in fact, penetrate through this intervening gas.

    In addition, the NuSTAR telescope can measure rapid X-ray pulsations with fine precision. In this particular case, NuSTAR was able to capture high-energy X-rays coming at regular fast-paced pulses from HESS J1640-465. These data led to the discovery of PSR J1640-4631, a pulsar spinning five times per second -- and the ultimate power source of both the high-energy X-rays and gamma rays.

    How does the pulsar produce the high-energy rays? The pulsar's strong magnetic fields generate powerful electric fields that accelerate charged particles near the surface to incredible speeds approaching that of light. The fast-moving particles then interact with the magnetic fields to produce the powerful beams of high-energy gamma rays and X-rays.

    The new data also allowed astronomers to measure the rate at which the pulsar slows, or spins down (about 30 microseconds per year), as well as how this spin-down rate varies over time. The answers will help researchers understand how these spinning magnets -- the cores of dead stars -- can be the source of such extreme radiation in our galaxy.




    YOU MAY ALSO LIKE

    A new study shows that it is possible to use an imaging technique called cryo-electron microscopy (cryo-EM) to view, in near-atomic detail, the architecture of a metabolic enzyme bound to a drug that blocks its activity. This advance provides a new path for solving molecular structures that may revolutionize drug development.
    Scientists have solved the riddle behind one of the most recognisable, and annoying, household sounds: the dripping tap. And crucially, they have also identified a simple solution to stop it, which most of us already have in our kitchens.
    Peering into the heart of the Milky Way galaxy, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) has spotted a mysterious glow of high-energy X-rays that, according to scientists, could be the "howls" of dead stars as they feed on stellar companions.
    A team of UK scientists have identified the mechanism behind hardening of the arteries, and shown in animal studies that a generic medication normally used to treat acne could be an effective treatment for the condition.
    A new study suggests that taking a B vitamin supplement may protect against certain epigenetic effects associated with air pollution.
    Six million years ago, grass-eating mammals became more diverse in South America. Shifts in tropical atmospheric circulation known as Hadley circulation led to changes in climate and vegetation, especially grasses, which expanded the mammals' range.

    © 1991-2023 The Titi Tudorancea Bulletin | Titi Tudorancea® is a Registered Trademark | Terms of use and privacy policy
    Contact