The most massive known star in the universe has just received its best close-up image yet, showing the star may be smaller than astronomers previously thought.
Astronomers photographed the star using the Gemini South telescope in Chile R136a1which is about 160,000 light-years from Earth at the center of the Tarantula Nebula in which Large Magellanic Cloud – a dwarf companion galaxy of the Milky Way. Their observations show that the giant star (and others like it) may not be as massive as previously thought.
“Astronomers have yet to fully understand how the most massive stars — more than 100 times the mass of the Sun — are formed,” it says a statement (opens in new tab) by the National Science Foundation (NSF) NOIRLab, which operates the Gemini South telescope. “A particularly challenging piece of this puzzle is obtaining observations of these giants, which normally reside in the densely populated hearts of dust-shrouded star clusters.”
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Gemini South’s Zorro instrument uses a technique known as speckle imaging that combines thousands of short-exposure images of stars deep within the planet universe to cancel the blur effect of earth atmosphere. This technique allowed astronomers to more precisely separate the brightness of R136a1 from its close stellar companions, resulting in the sharpest image of the giant star ever recorded.
While previous observations suggested that R136a1 was between 250 and 320 times more massive than that Sunthe new Zorro observations show that the giant star’s mass could be closer to 170 to 230 times that of the Sun – still qualifying it as the most massive star known.
“Our results tell us that the most massive star we currently know is not as massive as we previously thought,” Venu M. Kalari, lead author of the study and astronomer at NSF’s NOIRLab, said in the statement. “This suggests that the upper limit of the stellar mass could also be smaller than previously thought.”
AND the brightness of the star and the temperature is based on its mass. In other words, more massive stars appear brighter and hotter. Astronomers estimated the mass of R136a1 by comparing the observed brightness and temperature to theoretical predictions. Because the new Zorro images more precisely separated the brightness of R136a1 from its close stellar companions, astronomers were able to estimate that the star is lower in brightness and therefore lower in mass than previous measurements indicated, the statement said.
Massive stars like R136a1 grow rapidly, burning up their fuel reserves in just a few million years before suffering a fiery death supernova Explosions, the seeds galaxies with heavy elements responsible for the formation of new stars and planets. This is the fate of most stars more than 150 times the mass of the Sun. However, if stellar masses are smaller than previously thought, supernovae could also be rarer than expected, the researchers noted.
The study was accepted for publication (opens in new tab) in the Astrophysical Journal.
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