Clearest ever image of the largest known star in the universe

Clearest ever image of the largest known star in the universe

Sitting at the center of the Tarantula Nebula in the Large Magellanic Cloud is the largest star ever discovered. With the help of the Zorro Imager and the 8.1-meter Gemini South Telescope in Chile, astronomers have captured the sharpest image ever of the star. This new image challenges our understanding of the most massive stars and suggests that they may not be as large as previously thought. Image credit: Gemini Observatory International/NOIRLab/NSF/AURAA Credits: Image Processing: TA Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) NOIRLab)

By harnessing the capabilities of the 8.1-meter Gemini South Telescope in Chile, part of the International Gemini Observatory operated by NSF’s NOIRLab, astronomers have obtained the clearest ever image of star R136a1, the largest known in the universe of stars. Their research, led by NOIRLab astronomer Venu M. Kalari, challenges our understanding of the most massive stars and shows that they may not be as large as previously thought.


Astronomers don’t yet fully understand how the most massive stars—those with more than 100 times the mass of the Sun—form. A particularly challenging piece of the puzzle is obtaining observations of these giant stars, which typically reside in the dense centers of dusty star clusters. Superstars also live fast and die early, depleting their fuel reserves in just a few million years. By comparison, our sun is less than half of its 10 billion-year lifespan. The combination of dense stars, relatively short lifetimes, and large astronomical distances makes distinguishing individual massive stars in clusters a formidable technical challenge.

By pushing the capabilities of the Zorro instrument on the Gemini South telescope at the International Gemini Observatory operated by NSF’s NOIRLab, astronomers have obtained the clearest image yet of R136a1, the most massive star known. The massive star is a member of the R136 star cluster, located about 160,000 light-years from Earth in the center of the Tarantula Nebula in the Milky Way’s dwarf companion galaxy, the Large Magellanic Cloud.

Previous observations have suggested that R136a1 is about 250 to 320 times the mass of the Sun. However, new Zorro observations suggest that the giant star may be only 170 to 230 times the mass of the sun. Even with this lower estimate, R136a1 still qualifies as the most massive star known.

Clearest ever image of the largest known star in the universe

This contrast image shows the extraordinary sharpness and clarity of the Zorro Imager on Chile’s 8.1-meter Gemini South Telescope (left) compared to earlier images from the NASA/ESA Hubble Space Telescope (right). New images of Gemini South allow astronomers to clearly distinguish star R136a1 from its nearby stellar companion, providing the data needed to reveal that — while it’s still the most massive star known in the universe — it’s more massive than before Think smaller.Image credit: Gemini Observatory International/NOIRLab/NSF/AURAA Credits: Image Processing: TA Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) ); NASA/ESA Hubble Space Telescope

Astronomers are able to estimate a star’s mass by comparing the observed brightness and temperature with theoretical predictions. The sharper Zorro image allowed NSF’s NOIRLab astronomer Venu M. Kalari and his colleagues to more accurately distinguish the brightness of R136a1 from its nearby stellar companion, which led to lower estimates of its brightness and mass.

“Our results show that the most massive stars we currently know are not as massive as we previously thought,” published in astrophysical journal. “This suggests that the upper limit of stellar mass may also be smaller than previously thought.”

The result also has implications for the origin of elements heavier than helium in the universe. These elements are produced when a star more than 150 times the mass of the Sun dies in a catastrophic explosion in an event that astronomers call a pair of unstable supernovae. If R136a1 is less massive than previously thought, then so are other massive stars, so pairing instability supernovae may be rarer than expected.

Astronomers have previously observed the star cluster that hosts R136a1 using the NASA/ESA Hubble Space Telescope and various ground-based telescopes, but none of these telescopes have been able to obtain images clear enough to identify all the individual stellar members of the nearby cluster.

Clearest ever image of the largest known star in the universe

This is a schematic illustration of the largest known star in the universe, R136a1, located in the Tarantula Nebula in the Large Magellanic Cloud. By harnessing the capabilities of the 8.1-meter Gemini South Telescope in Chile, a team of astronomers has obtained the sharpest image ever of the giant star. Image credit: NOIRLab/NSF/AURA/J.Da Silva/Space Engine

Gemini South’s Zorro instrument is able to surpass the resolution of previous observations by using a technique called speckle imaging, which allows ground-based telescopes to overcome much of the blurring effects of Earth’s atmosphere. Almost all of this blur can be removed by taking thousands of short exposure images of bright objects and carefully manipulating the data. This approach, along with the use of adaptive optics, could significantly improve the resolution of ground-based telescopes, as the team’s new Zorro observations of R136a1 have shown.

“This result shows that, 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,” co-author Ricardo Sally Nas commented. The authors of the paper and Zorro’s instrument scientist. “This observation pushes the boundaries of what speckle imaging has thought possible.”

“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.”

Zorro and its twin instrument “Alopeke” are the same imagers installed on the Gemini South and Gemini North telescopes, respectively. Their names are Hawaiian and Spanish for “fox”, which represent the telescope’s respective locations in Mauna Kea, Hawaii, and Cerro Pahon, Chile. The instruments are part of the Gemini Observatory’s Visiting Instruments program, which advances new science by housing innovative instruments and fostering exciting research. Steve B. Howell, the current chairman of the Gemini Observatory’s board of directors and a senior research scientist at NASA’s Ames Research Center in Mountain View, California, is the principal investigator for both instruments.

“Gemini South continues to enhance our understanding of the universe and transform astronomy as we know it. This discovery is yet another example of the scientific feats we can accomplish when we combine international collaboration, world-class infrastructure and a first-class team,” said the NSF Gemini Project Officer Martin Still.


Astronomers get new images of R136, the most massive star ever discovered


More information:
Analyze the core of R136 in optics, astrophysical journal (2022). DOI: 10.3847/1538-4357/ac8424

Provided by the Association of Universities for Research in Astronomy (AURA)

Citation: The sharpest image of the most massive known star in the universe (2022, August 19) on August 19, 2022 from https://phys.org/news/2022-08-sharpest-image-universe- massive-star.html retrieved

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