September 16, 2014
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, California
Our Milky Way galaxy is littered with the still-sizzling remains of exploded stars.
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. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, discovered the pulsar by identifying its telltale pulse — a rotating beam of X-rays, that like a cosmic lighthouse, intersects Earth every 0.2 seconds.
The pulsar, called PSR J1640-4631, lies in our inner Milky Way galaxy about 42,000 light-years away. It was originally identified by as an intense source of gamma rays by the High Energy Stereoscopic System (H.E.S.S.) in Namibia. NuSTAR helped pin down the source of the gamma rays to a pulsar.
The other pink dots in this picture show low-energy X-rays detected by NASA’s Chandra X-ray Observatory.
In this image, NuSTAR data is blue and shows high-energy X-rays with 3 to 79 kiloelectron volts; Chandra data is pink and shows X-rays with 0.5 to 10 kiloeletron volts.
The background image shows infrared light and was captured by NASA’s Spitzer Space Telescope.
Image credit: NASA/JPL-Caltech/SAO
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?
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,” said Eric Gotthelf of Columbia University, New York. Gotthelf explained that 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. Gotthelf is lead author of a new paper describing the findings in the Astrophysical Journal.
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, caled 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 discovery of a pulsar engine powering HESS J1640-465 allows astronomers to test models for the underlying physics that result in the extraordinary energies generated by these rare gamma-rays sources,” said Gotthelf.
“Perhaps other luminous gamma-ray sources harbor pulsars that we can’t detect,” said Victoria Kaspi of McGill University, Montreal, Canada, a co-author on the study. “With NuSTAR, we may be able to find more hidden pulsars.”
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.
See the full article here.
The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.
President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.
Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.
NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble,
Chandra, Spitzer ]and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.
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