Betelgeuse is ‘a bit dusty’ and will not soon become a supernova
The huge red super giant Betelgeuse will not soon become supernova if astronomers discover that it is ‘just a little dusty’.
Last year the giant star began to dim and at one point reached only 30 percent of its usual brightness, giving rise to some speculation that it was about to explode.
The star is beginning to regain some of its old brightness and a new study from the University of Washington suggests that the dimming came from a cloud of dust.
In a paper accepted by Astrophysical Journal Letters and in collaboration with the Lowell Observatory, astronomers report on the surface temperature of the star.
The team discovered that it was hotter than they would expect if it started to cool down before it went supernova and has probably shed some of its material.
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This artist’s impression shows the super giant star Betelgeuse as it would be if he were in the solar system – the outer edge would end up as far as Jupiter and swallow the inner planets
The surface of Betelgeuse has been captured by astronomers using the Very Large Telescope array – it started to dim at the end of last year but is now becoming brighter
This material then formed as a cloud of gas and dust in front of the star, as viewed through Earth’s telescopes – making the star look duller until the cloud moves away.
Emily Levesque from the University of Washington and Philip Massey from the Lowell Observatory worked on the research.
They examined Betelgeuse observations taken at the Flagstaff, Arizona observatory on February 14 and calculated an average surface temperature for the star.
They discovered that it is “considerably warmer” than would be expected if the recent dimming was caused purely by a cooling of the surface of the star.
The astronomers say that massive red super giant stars tend to shed some material from the outer layers from time to time.
“We see this in red super giants all the time, and it’s a normal part of their life cycle,” Levesque said in a report from Phys.org.
“Red super giants occasionally throw material from their surface, which will condense around the star like dust.
“As it cools and disappears, the dust grains absorb a part of the light coming at us and block our view.”
This does not mean that Betelgeuse will not explode – in fact, astronomers know for certain that this will happen at some point in the next 100,000 years.
The star is also 700 light-years away, so the light we see now and the observations from the earth actually happened 700 years ago.
It will become supernova when its core eventually collapses and while it appears to dim when that happens – it is not necessarily a sign of an impending explosion.
“A simple way to distinguish between these options is to determine the effective surface temperature of Betelgeuse,” Massey said.
Supernova occurs when a giant star, similar to Betelgeuse, reaches the end of its lifespan and runs out of fuel to burn – it condenses within itself and then spreads its material in a giant explosion.
Betelgeuse began dimming at the end of last year with astronomers who noted that it was the most boring thing it had been since the star’s observations began decades earlier.
Some astronomers predict that there is a large cloud of gas and dust between the star and the earth that makes it invisible to us
To get a better picture of what happened to the star, astronomers used the European Large Observatory (ESO) Very Large Telescope array in Chile to show it in unprecedented detail.
The stunning new images of the red super giant were captured by the ‘Very Large Telescope’ in Chile and compared with similar images from 11 months of dramatic changes in the star.
Levesque and Massey decided to further investigate the star and view it of different wavelengths to calculate the surface temperature.
“Emily and I had been in contact about Betelgeuse, and we both agreed it was obvious to get a spectrum,” Massey said.
“I had been watching the 4.3-meter Lowell Discovery telescope all the time, and I knew that if I played a little, I could get a good spectrum, despite Betelgeuse still being one of the brightest stars in the sky is. “
According to their calculations, the average surface temperature of Betelgeuse on February 14 was approximately 6,017 degrees Fahrenheit.
That is only about 120 degrees Fahrenheit cooler than the temperature that an earlier team like the surface temperature of Betelgeuse calculated in 2004.
At one point the star reached only 30 percent of its usual brightness – as can be seen in these comparison photos taken between January 2019 and December 2019
“A comparison with our 2004 spectrum immediately showed that the temperature had not changed significantly,” Massey said. “We knew the answer had to be dust.”
Astronomers have observed dust clouds around other red super giants, and additional observations can reveal similar clutter around Betelgeuse.
Even if the recent dimming was not an indication that the star would explode rapidly, towards Levesque and Massey, that is no reason to stop searching.
“Red super giants are very dynamic stars,” Levesque said.
“The more we can learn about their normal behavior – temperature fluctuations, dust, convection cells – the better we can understand and recognize them when something really unique, such as a supernova, could happen.”
The research paper has been accepted for publication by Astrophysical Journal Letters and published on the preprint site arXiv.
WHAT IS A SUPERNOVA AND HOW IS IT FORMED?
A supernova occurs when a star explodes and shoots debris and particles into space.
A supernova only burns for a short period, but it can tell scientists a lot about how the universe started.
One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever-increasing pace.
Scientists have also found that supernovas play a key role in spreading elements throughout the universe.
In 1987, astronomers saw a “titanic supernova” in a nearby galaxy with a power of more than 100 million suns (photo)
There are two known types of supernova.
The first type occurs in binary star systems when one of the two stars, a white carbon dwarf, steals matter from its companion star.
Ultimately, the white dwarf collects too much matter, causing the star to explode, resulting in a supernova.
The second type of supernova occurs at the end of the life of a single star.
When the star runs out of nuclear fuel, part of its mass flows into its core.
Ultimately, the core is so heavy that it cannot bear its own gravity and the core collapses, resulting in a new giant explosion.
Many elements on Earth are made at the core of stars and these elements travel further to form new stars, planets and everything else in the universe.
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