Studying dust produced by 'twinkling' stars could shed light on planet creation

Astronomers have discovered a coincidence between the varying intensity of dusty asymptotic giant branch (AGB) stars, a kind of star slightly larger and older than our Sun, and variations in the amount of dust these stars produce.

The astronomers from University of Tokyo, Japan, said that since the dust thus produced could lead to creation of planets, studying it could shed light on the origins of and, in turn, life on Earth.

AGB stars are generally known to be producers of dust in the interstellar medium existing between and among stars. Among these, dusty AGBs are particularly prominent dust producers, shining light that varies widely.

The research team’s long-period survey findings came from studying the data produced by AKARI and WISE, two infrared (IR) space telescopes surveying the cosmos. While these telescopes have concluded their initial missions, astronomers continue to make discoveries from the data they have produced.

The researchers have published their findings in the journal Publications of the Astronomical Society of Japan.

Lead researcher Kengo Tachibana said that the IR light coming from stars is a key source of information, helping astronomers unlock their secrets.

“Until recently, most IR data was from very short-period surveys due to the lack of advanced dedicated platforms. But missions like AKARI and WISE have allowed us to take longer-period surveys of things.

“This means we can see how things might change over greater time periods, and what these changes might imply.

“Lately, we turned our attention to a certain class of star known as asymptotic giant branch stars, which are interesting because they are the main producers of interstellar dust,” said Tachibana.

Interstellar dust refers to heavy elements dispersing from stars, leading to the formation of solid objects including planets.

The astronomers said that it is yet unclear as to what the main drivers of this dust production are and where they should be looking to find this out.

“Our latest study has pointed us in the right direction,” said Tachibana. “Thanks to long-period IR observations, we have found that the light from dusty AGBs varies with periods longer than several hundred days.

The astronomers further found that the spherical shells of dust produced by and then ejected by these stars have concentrations of dust that vary in step with the stars’ changes in luminosity.

“Of the 169 dusty AGBs surveyed, no matter their variability period, the concentrations of dust around them would coincide. So, we’re certain these are connected,” said Tachibana.

The team of astronomers intends to continue their investigation by monitoring various AGB stars for many years continuously to explore the possible physical mechanisms behind dust production.