September 26, 2022

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Set the clock to a starburst

Set the clock to a starburst

Photo: NASA/CXC/GSFC/BJ Williams et al. ; Optical: NASA/ESA/STScI

Although astronomers have seen the fragments of dozens of exploding stars in the Milky Way and nearby galaxies, it is often difficult to determine the timeline of the star’s demise. By studying the astonishing remnants of a supernova in a neighboring galaxy using NASA telescopes, a team of astronomers has found enough evidence to turn back the clock.

The supernova remnant, called SNR 0519-69.0 (abbreviated SNR 0519), is the debris from the explosion of a white dwarf star. After the star reached critical mass by pulling matter away from the companion star or merging with another white dwarf, it underwent a thermonuclear explosion and was destroyed. Scientists use this type of supernova, called Type Ia, for a variety of scientific studies, from studies of thermonuclear explosions to measuring distances to galaxies over billions of light years. SNR 0519 is located in the Large Magellanic Cloud, a small galaxy 160,000 light-years from Earth. This composite image shows X-ray data from NASA’s Chandra X-ray Observatory and optical data from NASA’s Hubble Space Telescope. Low, medium, and high-energy X-rays of SNR 0519 appear in green, blue, and purple, respectively, with some of these colors overlapping to appear white. The optical data shows the outline of the remnants in red and the stars around the remainder in white.

Astronomers combined data from Chandra and Hubble with data from NASA’s retired Spitzer Space Telescope to determine how long the star has exploded at SNR 0519 and to learn more about the environment in which the supernova occurred. This data provides scientists with an opportunity to “rewind” the movie of stellar evolution that has since begun and determine when it began. The researchers compared Hubble images from 2010, 2011 and 2020 to measure material velocities in the blast shock wave, which range from about 3.8 million to 5.5 million miles (9 million kilometers) per hour. If the speed is at the higher end of these estimated speeds, astronomers have determined that the light from the explosion would have reached Earth about 670 years ago, or during the Hundred Years’ War between England and France and at the height of the Ming dynasty. In China.

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However, it is possible that the material has slowed down since the first eruption and that the eruption occurred as recently as 670 years ago. Chandra and Spitzer data suggest that this is the case. The astronomers found that the brightest X-ray regions in the remains are where the slowest-moving material is, and that there are no X-rays associated with the fastest-moving material. These results indicate that part of the blast wave hit the dense gas around the remnant, slowing it down on its journey. Astronomers can use additional observations with Hubble to more accurately determine the star’s demise time.

An article on these findings was published in the August issue of The Astrophysical Journal, and a preliminary version is available here. The authors of the article are Brian Williams (NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Maryland); Parviz Javamian (Towson University, Towson, Maryland); Evo Sittenzal (University of New South Wales, Australian Defense Force Academy, Canberra, Australia); Stephen Reynolds (North Carolina State University (NCSU), Raleigh, NC); Kazimierz Borkowski (North Carolina State University, Raleigh, NC) and Robert Petrie (GSFC). NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center manages science operations out of Cambridge, Massachusetts, and flight operations out of Burlington, Massachusetts.

source: NASA