~Proxima Centauri~

[Heathcliff]

Earth-Like Planet Found Orbiting the Nearest Star to the Sun



The next star over has a planet that's kinda like ours.

Astronomers just discovered the closest possible Earth-like planet outside our solar system. It orbits our closest neighboring star, Proxima Centauri. The planet is warm enough for liquid water, is almost certainly rocky and terrestrial, and could even have an atmosphere. At just 4.2 light years away, scientists are even wondering if this may be the closest home for life outside our solar system.

The newly discovered planet has been temporarily named Proxima B by its discoverers, an international team led by astronomer Guillem Anglada-Escudé at Queen Mary University in London. Proxima B is roughly 30 percent larger than Earth, and closely orbits a star far cooler and smaller than our own. Following a month of rumors and hints, Proxima B was unveiled today in a paper in the journal Nature.

"What's amazing is how close it is," says Jeff Coughlin, a SETI astronomer working with NASA's Kepler planet-hunting mission, who was not involved in the discovery. "There's nothing in physics that would keep us from sending a probe to Proxima B within the next few decades, even with just current day technology."

THE HUNT BEGINS

To appreciate what we know (and don't know) about Proxima B, it helps to understand how the planet was discovered. Astronomers have not yet directly seen or snapped images of the planet. Rather, Proxima B was detected after roughly 16 years of analyzing telescopic recordings of the planet's star, Proxima Centauri.

After combining all those recordings, scientists found the planet in a peculiar wobble of the star. They saw that Proxima Centauri wobbles toward and away from Earth in a cycle every 11 days plus a few hours . This movement can be detected in a slight shift in the color of the starlight, via the Doppler effect.

https://youtu.be/pJWZ7ikJR2k

Overall, astronomers combined hundreds of observations. The effort recently ramped up after a tantalizing early whiff of Proxima B. Finally, the scientists determined that this wobbling is due to a delicate, tugging ballet between Proxima Centauri and a planet that orbits the star every 11.2 days. Although they could not see Proxima B, the astronomers could calculate the world's size and distance from its star by crunching the numbers on Proxima Centauri's wobble and estimated mass.

This roundabout way of planet-hunting may sound uncertain, "but statistically there is no doubt about this signal," says Anglada-Escudé. Taking this info Proxima B's size and orbit, scientists have estimated that it is rocky like Earth and perfectly situated in its stars habitable zone, a place where liquid water should neither entirely boil nor freeze.

RED DWARF

Proxima Centauri is not like our sun. It's a cooler, smaller, and far more common type of star called a red dwarf. According to Ansgar Reiners, one of the astronomers behind today's discovery who's based at the University of Göttingen in Germany, this fact makes the case for life on Proxima B a more complex calculation.

For one thing, "Proxima Centauri is a relatively active star, so Proxima B receives rough 100 [times more] more high-energy radiation than Earth," he says. Reiners is talking about stuff like gamma radiation that could be potentially fatal for microbes. But if Proxima B has a protective magnetic field and atmosphere like our own, then life could certainly still exist there—especially in oceans.

https://youtu.be/G_VhV6Qv674

Proxima B is also pretty darn close to its star. Where Earth is 93 million miles from the sun on average, Proxmia B and its star are just 4 million miles apart—5 percent as far. Because red dwarfs are so much cooler than our Sun, the planet can be this close without getting charred to a crisp.

Yet this proximity could cause two problems. First, Proxima B is likely to be tidally locked, meaning the same face of the planet always faces the star. It's like the way the same side of the moon always faces the Earth. (However, a thick enough atmosphere could keep the world twirling.) Second, depending on how and when Proxima B was formed, early blasts of stellar radiation could have blown away much or most of Proxima B's hypothetical atmosphere.

That said, "none of this excludes the possibility of an atmosphere and water, it all depends on the history of the stellar system," Reiners says.



https://youtu.be/MbkNuDJ5PaQ