Scientists have discovered two new types of low-mass Red Giants. And they're pretty weird ...

Credit image: NASA - a Red Giant
Credit image: NASA - a Red Giant

Article by: Andacs Robert Eugen, on 18 April 2022, at 01:35 pm Los Angeles time

Scientists have discovered two other types of red giants.

The Red Giants are stars that burned all their hydrogen from helium nuclei through a process of nuclear fusion.

Also, our Sun will be transformed into a Red Giant in approx. 4-5 billion years.

Until now, there have been various theories that astronomers claim that there are also weaker red giants in smaller masses.

Now, thanks to the research of Yaguang Li and his team at the University of Sydney, the theory has become a certainty.

"It's like finding Waldo. We were extremely lucky to find 39 slimmer red giants, hidden in a sea of normal ones. The slimmer red giants are either smaller in size or less massive than normal red giants," said Li.

"How and why did they slim down? Most stars in the sky are in binary systems - two stars that are gravitationally bound to each other."

"When the stars in close binaries expand, as stars do as they age, some material can reach the gravitational sphere of their companion and be sucked away."

"In the case of relatively tiny red giants, we think a companion could possibly be present." continue Li.

They use the technique asteroseismology and analyzed data collected by NASA's Kepler Space Telescope from more than 7,500 helium-burning red giants.

Thus, scientists have discovered two types of red giants: very low-mass red giants, and underluminous red giants.

The first type, very low-mass, are stars that had a mass of 0.5-0.7 solar masses. That is, somewhere more than half the mass of our Sun.

And the second type, underluminous red giants are stars that had a mass of 0.8-2 solar masses. 

Also, researchers concluded in the end that only 7 stars of this type were found, but they expect to find more in the future.

"The problem is that most of them are very good at blending in. It was a real treasure hunt to find them," Dr. Murphy said.

"They've slimmed down somewhat and because they're smaller, they're also fainter, hence 'underluminous' compared to normal red giants."

Source: Nature Astronomy

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