Look at that: Planetary bodies observed in habitable zone of ... dead star

12/04/2022
Credit image: NASA - An artist's concept of a planetary system
Credit image: NASA - An artist's concept of a planetary system

Article by: Andacs Robert Eugen, on 12 April 2022, at 11:48 am Los Angeles time

Astronomers have discovered something really strange, which previously seemed almost unbelievable.

Their research shows that planetary bodies the size of a moon orbit a dead star. But the strangest thing is that the planetary bodies are framed in the potential "habitable zone", while their star is dead

The research team observed a white dwarf (dead star), 117 light-years from Earth, named WD1054-226. They made long observations on its changing light during 18 nights (the reference to time is made for the planetary system where the dwarf star is).

The scientists used the ULTRACAM high-speed camera on the ESO 3.5 m New Technology Telescope (NTT) at La Silla Observatory in Chile.

The project was quite complex, so the scientists also needed data from NASA Transiting Exoplanet Survey Satellite (TESS).

Thus, astronomers have pointed out one detail in these observations and that of dips in light, being equivalent to 65 clouds of uniformly spaced planetary debris orbiting the white dwarf every 25 hours.

After much data and detailed calculations, scientists have come to the conclusion that it is most likely a planet that holds these structures and maintains the accuracy of their arrangement so precisely.

The distance between the small star and this possible exoplanet is approx. 1.7% of the Sun-Earth distance. Also, the size of the planet can be about the same as that of one of our planets in the solar system.

And how is there a habitable zone in that system?

Well, the rather short distance between the white dwarf and the possible planet creates a possibility that life could be sustained on that planet.

A white dwarf releases heat and light, but in a much smaller quantity than our Sun.

So the distance between a possible planet and WD1054-226 must be smaller, and the "habitable zone" portion will be much smaller than that of a system with a still active star.

Structures, including the planet, may have arrived / formed after the star became white dwarf.

Before a star becomes a white dwarf, it turns into a red giant, and the very short distance between the structures and the white dwarf makes researchers wonder if these structures were brought or formed only after the star became a white dwarf.

Researchers are also considering the possibility that the orbit of the star, which is now a white dwarf, has been cleared by the red giant, so that everything that exists now is something new.

If so, and there really is an exoplanet there, then that exoplanet could support life for at least a billion years in the future from now on.

Lead author Professor Jay Farihi said the following:

"This is the first time astronomers have detected any kind of planetary body in the habitable zone of a white dwarf.

"The moon-sized structures we have observed are irregular and dusty (e.g. comet-like) rather than solid, spherical bodies. Their absolute regularity is a mystery we cannot currently explain.

"An exciting possibility is that these bodies are kept in such an evenly-spaced orbital pattern because of the gravitational influence of a nearby major planet. Without this influence, friction and collisions would cause the structures to disperse, losing the precise regularity that is observed. A precedent for this 'shepherding' is the way the gravitational pull of moons around Neptune and Saturn help to create stable ring structures orbiting these planets.

"The possibility of a major planet in the habitable zone is exciting and also unexpected; we were not looking for this. However, it is important to keep in mind that more evidence is necessary to confirm the presence of a planet. We cannot observe the planet directly so confirmation may come by comparing computer models with further observations of the star and orbiting debris."

"Since our Sun will become a white dwarf in a few billion years, our study provides a glimpse into the future of our own solar system."

Source: https://ras.ac.uk/news-and-press/research-highlights/planetary-bodies-observed-habitable-zone-dead-star

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