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Astronomers Discover the ‘Biggest Stellar Puzzle’, Bizarre Star that Refuses to Die

The study calculated that the star that exploded was at least 50 times more massive than the Sun and probably much larger.

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This star shines brighter every time it explodes. Read to know more! (representative image) Wikimedia

New York, November 9, 2017 : An international team of astronomers has made a bizarre discovery – a star that refuses to stop shining despite exploding more than once over a period of 50 years.

The explosions of stars, known as supernovae, have been observed in the thousands and in all cases they marked the death of a star.

But a new study, published in the journal Nature, challenges known theories about the death of stars. Their observations included data from Keck Observatory on Maunakea in Hawaii.

“The spectra we obtained at Keck Observatory showed that this supernova looked like nothing we had ever seen before. This, after discovering nearly 5,000 supernovae in the last two decades,” said study co-author Peter Nugent from Lawrence Berkeley National Laboratory in the US.

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“While the spectra bear a resemblance to normal hydrogen-rich core-collapse supernova explosions, they grew brighter and dimmer at least five times more slowly, stretching an event which normally lasts 100 days to over two years,” Nugent said.

The supernova, named iPTF14hls, was discovered in September 2014 by the Palomar Transient Factory. At the time, it looked like an ordinary supernova.

Several months later, astronomers at Las Cumbres Observatory in the US noticed the supernova was growing brighter again after it had faded.

When astronomers went back and looked at archival data, they were astonished to find evidence of an explosion in 1954 at the same location.

This star somehow survived that explosion and exploded again in 2014.

“This supernova breaks everything we thought we knew about how they work. It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions,” said lead author Iair Arcavi, a NASA Einstein postdoctoral fellow at LCO and the University of California Santa Barbara.

The study calculated that the star that exploded was at least 50 times more massive than the Sun and probably much larger.

Supernova iPTF14hls may have been the most massive stellar explosion ever seen. The size of this explosion could be the reason that conventional understanding of the death of stars failed to explain this event.

Astronomers continue to monitor the supernova, which remains bright three years after it was discovered. (IANS)

 

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Astronomers Measure Mass of Milky Way Galaxy

The Milky Way, the galaxy which contains Earth's solar system, is home to up to 400 billion stars and an estimated 100 billion planets.

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Milky way galaxy, scientists
The measurement includes all the stars and planets, dust and gas, as well as the four-million-solar-mass supermassive black hole at the center. Pixabay

Using data from NASA’s Hubble Space Telescope and the European Space Agency’s Gaia satellite, astronomers have come up with one of the most accurate measurements of mass of the Milky Way galaxy.

While previous research dating back several decades provided estimates for our galaxy’s mass, ranging between 500 billion to three trillion solar masses, according to the latest measurements, Milky Way weighs about 1.5 trillion solar masses (one solar mass is the mass of our Sun).

The measurement includes all the stars and planets, dust and gas, as well as the four-million-solar-mass supermassive black hole at the center.

“We want to know the mass of the Milky Way more accurately so that we can put it into a cosmological context and compare it to simulations of galaxies in the evolving universe,” said Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore, Maryland.

milky way galaxy, scientists
The more massive a galaxy, the faster its globular clusters move under the pull of gravity, according to a forthcoming paper in The Astrophysical Journal. Pixabay

To weigh the galaxy, the team augmented Gaia measurements for 34 globular clusters out to 65,000 light-years, with Hubble measurements of 12 clusters out to 130,000 light-years that were obtained from images taken over a 10-year period.

They also measured the three-dimensional movement of globular star clusters – isolated spherical islands each containing hundreds of thousands of stars each that orbit the center of our galaxy.

The more massive a galaxy, the faster its globular clusters move under the pull of gravity, according to a forthcoming paper in The Astrophysical Journal.

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The new mass estimate puts our galaxy on the beefier side, compared to other galaxies in the universe. The lightest galaxies are around a billion solar masses, while the heaviest are 30 trillion, or 30,000 times more massive.

The Milky Way, the galaxy which contains Earth’s solar system, is home to up to 400 billion stars and an estimated 100 billion planets. (IANS)