Betelgeuse is usually the tenth-brightest star in the night sky and the brightest star in the night sky at near-infrared wavelengths. It is a distinctly reddish semiregular variable. It is classified as a red supergiant, calculated to be about 700 light-years from the Sun, and to have less than 10 million years old.
Betelgeuse is generally considered to be a single isolated star and a runaway star. The red giant has a mass range from slightly under ten to a little over twenty times that of the Sun. Because of its large mass, it evolved rapidly and is expected to end its evolution with a supernova explosion, most likely within 100,000 years.
Being a runaway, Betelgeuse is also racing through space, so comparisons of its current mass loss to the total lost mass are difficult. This is why, when it showed a drop to around 40% of its usual brightness last year, worries were that it might speed up the process and that we might witness its explosion. But, scientists at the University of Washington and Lowell Observatory say that the absorbance of light caused the sudden dim by molecules of titanium oxide.
The new study on Betelgeuse
Researchers studied the giant’s oscillations of temperature. If it were the case of an imminent explosion, then the temperature of Betelgeuse should register a massive drop in temperature. There is no significant change in the infrared over the last 50 years, and it seems unrelated to the recent visual fading, suggesting that an impending core-collapse may be unlikely. It was most likely due to the absorbance of light done by large-grain circumstellar dust.
It’s not an easy task to measure the temperature of a gas giant located 642,5 light-years, as this is the distance between Earth and Betelgeuse. So, they do it by looking at the spectrum of light emanating from it.
The light from a bright star, such as Betelgeuse, is too intense for a complete spectrum needed to determine the temperature. So, they used a filter to moisten the signal and watch the absorbance of light done by titanium oxide. Gas-phase titanium oxide shows strong bands in the optical spectra of cool (M-type) stars such as Betelgeuse, helping scientists to determine temperature.
Betelgeuse’s average surface temperature on Feb. 14 when compared with the temperatures in 2004 show just a slight decrease of only 50-100 degrees Celsius. And, lately, the giant started to brighten again. So, the red giant won’t turn into a supernova soon.