Hyperrealistic illustration of R136a1, shown as a bluish-white light spot in the center. It is much larger than all the other colored light spots around.

Largest known star in universe captured in unprecedented clarity

In short, the most massive known stars in the universe are smaller than scientists once thought.But even after docking several floors, this amazing balloon is still The most massive known star in the universe. That’s how huge it is.

Affectionately named R136a1, the luminous giant lives 160,000 light-years from Earth at the center of a stunning, multifilamentary star factory known as the Tarantula Nebula. Last week, astronomers announced that observations of the celestial object collected with the Gemini South Telescope in Chile had produced the sharpest images ever seen — thus revealing its true importance.

Over the years, data have suggested that the star is 250 to 350 times the mass of the Sun. But according to research the team plans to publish in The Astrophysical Journal, the new view suggests it’s more like 170 to 230 times the mass of our host star.

However, the R136a1 is a gleaming monster.

“Even with the lower estimates, R136a1 still qualifies as the most massive star known,” the team said in a press release.

For context, the Earth has a mass of about 6,000,000,000,000,000,000,000,000 kilograms (don’t think about that number, just get a feel for it). Jupiter’s mass is even 318 times that. This all accounts for only two worlds in our cosmic neighborhood. However, the sun makes up 99.8% of the mass of the earth all solar system. If this hurts your brain, another way to think about the size difference is that the sun can fit a million Earths inside.

Yes. The mass of R136a1 is 170 to 230 times that of the Sun. Do whatever you want with this information.

Artist’s illustration of R136a1, the largest known star in the universe, located within the Tarantula Nebula in the Large Magellanic Cloud. Maybe one day we’ll get an image of this stellar body clear enough to even rival this portrait.

NOIRLab/NSF/AURA/J. Da Silva/Space Engine

For the purposes of scientific advancement, “this suggests that the upper limit of stellar mass may also be smaller than previously thought,” Venu M. Kalari, an astronomer at the National Science Foundation’s NOIRLab and lead author of the paper, said in a press release.

Additionally, Kalari’s results could hint at our understanding of certain elements in the universe, particularly those produced by the exploding deaths of stars over 150 solar masses — those that accompany the largest explosions.

OK, but why didn’t we know that before?

Basically, the most spectacular, hot, and massive stars in the universe are usually also the most ephemeral, distant, and mysterious stars.

First, really massive stellar bodies tend to reside in densely populated star clusters that are obscured by remnant stardust, such as R136a1 in the Tarantula Nebula. This makes it difficult for ground-based equipment to discern the precise mass of a giant star of interest—other stars would interfere with observations.

On the right is a super blurred version of the cluster with R136a1. The star at hand almost merges with the star next to it. On the left is a new image of the area we have - it's much sharper.

This image shows the sharpness and clarity of the Zorro Imager on Chile’s 8.1-meter Gemini South Telescope (left) compared to an earlier image of R136a1 taken by the NASA/ESA Hubble Space Telescope (right).

Gemini International Observatory/NOIRLab/NSF/AURA Acknowledgements: Image Processing: TA Rector (University of Alaska Anchorage/NOIRLab at NSF), M. Zamani (NOIRLab at NSF) and D. de Martin (NOIRLab at NSF); NASA/ESA Hubble Space Telescope

NOIRLab, the group that operates the Gemini South Telescope, said: “Giant stars also live fast and die early, depleting their fuel reserves in just a few million years. Our sun, by contrast, is less than 10 years old. Half. Billion-year lifespan.” Aka, the already daunting task of identifying supermassive stars in dusty clusters has a little time limit.

That’s where the Gemini South Telescope comes in.

To image R136a1 with unprecedented clarity, the machine used a special instrument called the Zorro to get around some (huge) stargazing obstacles. Zorro used a technique called speckle imaging, which helps the telescope overcome the blurring effects caused by Earth’s atmosphere. Atmospheric ambiguity is such a big obstacle to telescopic observations that, in fact, it’s why NASA launched the Hubble Space Telescope in 1990.At the time, the goal was to get a shot above The atmosphere of our planet for beautiful, clear cosmic pictures.

On the ground, however, Zorro circumvented the atmospheric blurring problem in a different way. It basically takes thousands of short-exposure R136a1 images, which are then digitally processed by the research team.

“Under the right conditions, an 8.1-meter telescope can rival not only the Hubble Space Telescope, but also the James Webb Space Telescope in angular resolution,” said Ricardo Sa, co-author of the paper and the instrument. Ricardo Salinas, a scientist at Zorro, said in a press release. “This observation pushes the boundaries of what speckle imaging has thought possible.”

The final combination of images was sharp enough for the team to distinguish the brightness of R136a1 from the light from its nearby stellar companion, which led to lower estimates of its brightness and mass. “Astronomers are able to estimate a star’s mass by comparing the observed brightness and temperature with theoretical predictions,” according to NOIRLab.

“We started this work as exploratory observations to understand Zorro’s ability to see this class of objects,” Carari said. “While we urge caution in interpreting our results, our observations suggest that the most massive stars may not be as large as previously thought.”

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