Why have hundreds of stars disappeared without trace?
source : www.unilad.com
A group of astronomers has discovered that about a hundred stars have disappeared from view over the past seventy years – and they don’t know why.
However, it’s not just three stars that leave astrologers baffled, but about a hundred stars that have seemingly disappeared from view over the past seventy years – a project titled Disappearing and appearing sources discovered during a century of observations (VASCO).
Led by Beatriz Villarroel of the Nordic Institute for Theoretical Physics, VASCO used data from 70 years ago in 2017 and compared it with more current data.
The historical data looked at a series of sky images taken by the Samuel Oschin Telescope from the top of Palomar Mountain, California in 1949, scanned by the US Naval Observatory (USNO).
The modern data was collected by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), recorded by the Haleakalā Observatory in Hawaii between 2010 and 2014.
The team then compared the historical and more current images of the sky, using software to analyze the light sources they expected to see in both data sets.
Of the 600 million expected light sources, 150,000 initially appeared to have disappeared when the images were taken in 1949, compared to images from 2010 to 2014.
A “subset” was later narrowed down to “about 24,000 candidates,” according to the study published in The Astronomical Journal.
Villarroel tells space.com: “You can never guarantee that it is not a (photographic) plate defect. But you can do some tests to rule out the most obvious things.
“Then you go to the deeper catalogs like the Sloan Digital Sky Survey (SDSS) or the new Dark Energy Camera Legacy Survey to see if you can find remnants of the object on those, and depending on what you find, you may get different results produce kind of candidates.”
The number was then further reduced to approximately “100 point sources,” “redder and (with) larger proper motions than typical USNO objects” that had seemingly disappeared over the 70-year period.
But what could have caused the light sources to disappear from view in less than a century?
Villarroel explains that this could be the result of “a kind of optical afterglow from gamma-ray bursts or fast radio bursts.”
“Such eruptions are predicted to have super-large amplitudes of around eight to 10 magnitudes, but fade away within a few minutes and appear to have no visible counterpart whatsoever when we look at the sites with large telescopes,” she says. say.
Or it could be the result of a “failed” supernova: a huge star that collapses so drastically into a black hole that it leaves no trace. However, these types of occurrences are incredibly rare.
Asteroids may also have had an impact, or gravitational lensing causing visible distortions.
Alien life has also been debated, while other life is using the hypothetical structure of the Dyson Sphere – “a mega-engineering project that surrounds a star with platforms that spin in tight formation,” as explained by space.com – to harvest energy wake up.
Ultimately, astronomers remain baffled – at least for now, Villarroel says: ‘We don’t know of any process where a star would simply disappear, other than this hypothetical failed supernova. Therefore, disappearing stars become interesting because we have not observed such things. in nature. The main principle was to look for things we thought were impossible.’
source : www.unilad.com
