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Explosion Coming That Will Change the Night Sky
Calvin College professor Larry Molnar and his students along with colleagues from Apache Point Observatory (Karen Kinemuchi) and the University of Wyoming (Henry Kobulnicky) are predicting a change to the night sky that will be visible to the naked eye.
“It’s a one-in-a-million chance that you can predict an explosion,” Molnar said of his bold prognostication. “It’s never been done before.”
This mesh shows the shape of the contact binary star system KIC 9832227 as the smaller star partially eclipses the larger one. For scale, the larger star has a radius 40 percent greater than our Sun. The orbital plane is tilted 53 degrees to the line of sight.
This is a teaser for a feature length documentary currently in production. It will likely be released around 2023. For more information, please visit: www.luminous-film.com
Molnar’s exploration into the star known as KIC 9832227 began back in 2013. He was attending an astronomy conference when fellow astronomer Karen Kinemuchi presented her study of the brightness changes of the star, which concluded with a question: Is it pulsing or is it a binary?
Also present at the conference was then Calvin College student Daniel Van Noord ’14, Molnar’s research assistant. He took the question as a personal challenge and made some observations of the star with the Calvin observatory.
Molnar’s prediction is that a binary star (two stars orbiting each other) he is monitoring will merge and explode in 2022.
“He looked at how the color of the star correlated with brightness and determined it was definitely a binary,” said Molnar. “In fact, he discovered it was actually a contact binary, in which the two stars share a common atmosphere, like two peanuts sharing a single shell.
“From there Dan determined a precise orbital period from Kinemuchi’s Kepler satellite data (just under 11 hours) and was surprised to discover that the period was slightly less than that shown by earlier data” Molnar continued.
This result brought to mind work published by astronomer Romuald Tylenda, who had studied the observational archives to see how another star (V1309 Scorpii) had behaved before it exploded unexpectedly in 2008 and produced a red nova (a type of stellar explosion only recently recognized as distinct from other types). The pre-explosion record showed a contact binary with an orbital period decreasing at an accelerating rate. For Molnar, this pattern of orbital change was a “Rosetta stone” for interpreting the new data.
Upon observing the period change to continue through 2013 and 2014, Molnar presented orbital timing spanning 15 years at the January 2015 meeting of the American Astronomical Society, making the prediction that KIC 9832227 may be following in the footsteps of V1309 Scorpii. Before taking the hypothesis too seriously, though, one needed to rule out other, more mundane, interpretations of the period change.
A simulated view of the contact binary system KIC 9832227. The larger star is about half again as wide as the Sun, whereas the smaller one is about 80% as wide as our star. The system lies about 1,800 light-years from Earth.
In the two years since that meeting, Molnar and his team have performed two strong observational tests of the alternative interpretations. First, spectroscopic observations ruled out the presence of a companion star with an orbital period greater than 15 years. Second, the rate of orbital period decrease of the past two years followed the prediction made in 2015 and now exceeds that shown by other contact binaries.
“Bottom line is we really think our merging star hypothesis should be taken seriously right now and we should be using the next few years to study this intensely so that if it does blow up we will know what led to that explosion,” said Molnar.
To that end, Molnar and colleagues will be observing KIC 9832227 in the next year over the full range of wavelengths: using the Very Large Array, the Infrared Telescope Facility, and the XMM-Newton spacecraft to study the star’s radio, infrared and X-ray emission, respectively.
The contact binary KIC 9832227 (red circles) is located in the constellation Cygnus, the Swan. Although astronomers aren’t sure how bright it will become if the stellar pair mergers, it could potentially rise to 2nd magnitude, easily naked eye.
Credit: L. Molnar / Calvin College
“The project is significant not only because of the scientific results, but also because it is likely to capture the imagination of people on the street,” said Walhout. “If the prediction is correct, then for the first time in history, parents will be able to point to a dark spot in the sky and say, ‘Watch, kids, there’s a star hiding in there, but soon it’s going to light up.’”
Chart shows the summer constellations of Cygnus and Lyra, with north up. The Northern Cross asterism is marked with the blue lines. The position of KIC 9832227 is shown with a red circle. It is in line with the three stars of the cross bar and, if it reaches 2nd magnitude in outburst, will be as bright as they are. Additionally, this chart shows a visualization of the swan Cygnus and of the lyre Lyra.
Molnar says that this is the beginning of a story that will unfold over the next several years, and people of all levels can participate.
“The orbital timing can be checked by amateur astronomers,” said Molnar. “It’s amazing the equipment amateur astronomers have these days. They can measure the brightness variations with time of this 12th magnitude star as it eclipses and see for themselves if it is continuing on the schedule we are predicting or not.”
Contacts and sources:
Matt Kucinski, Lynn Rosendale
Calvin College
Source:
That should be cool to see. If the explosion doesn’t get us.