According to a paper in Nature, scientists have discovered a planet about the size of Earth around the closest star to the sun, Proxima Centauri, and its distance from the star is just enough to allow the existence of liquid water. The discovery fulfills a long-standing dream of science fiction writers: a planet that is likely to be habitable and close enough to Earth for humans to send probes and even manned spacecraft.
“We’ve already started searching for life on it,” said Guillem Anglada-Escudé, an astronomer at Queen Mary University of London who led the discovery team.
Humanity’s first opportunity to explore the planet may be Hawking’s recently announced Breakthrough Starshot initiative, which will build thousands of postage stamp-sized nanoscale spacecraft over the next few decades, using lasers Pushing, the speed can reach 20% of the speed of light. If the plan goes well, they could travel a distance of 1.3 parsecs from Earth to Proxima Centauri in 20 years.
The newly discovered planet Proxima Centauri has a mass at least 1.3 times that of Earth. Proxima Centauri itself is a red dwarf star, much smaller and dimmer than the sun, with an orbital period of 11.2 days. “Conditions for both stars and planets are so good, it’s exactly what we want to see, and it’s exciting,” said astronomer David Kipping of Columbia University.
Previous research has hinted at the possible existence of a planet around Proxima Centauri. Since 2000, the European Southern Observatory (ESO) in Chile has been using spectrometers to search for changes in the wavelength of starlight caused by the (possible) planet’s gravitational tug on the star, and the results show that the star appears fixed every 11.2 days. Variety. However, astronomers have been unable to determine whether the signal came from the orbital motion of the planet or another activity in the star itself, such as a flare.
The terrestrial planet orbits Proxima every 11.2 days. Image credit: Ricardo Ramirez
“This time it’s probably true”
In January 2016, Anglada-Escudé and colleagues launched a mission to determine whether the planet even existed. With ESO approval and support, they looked at the sky every night from January 19 to March 31 with another telescope’s planet-hunting facility. After collecting 10 hard evidence, they ended their observations.
The research team called this research project the “Dark Red Dot” project (the famous photo of Earth taken by Voyager 1 in the distance in 1990 was called the “Dark Blue Dot”, hence the name), due to its proximity to the The star is a red dwarf, and its planets will also appear red or orange, perhaps bathed in a radiance like the sunset on Earth. Although the planet’s position allows liquid water to exist, there may be other factors that make it uninhabitable, such as tidal locking—that is, the planet always faces the same side of the star (like the moon does to Earth), which would cause the star-facing hemisphere to be extremely hot, while the other hemisphere is extremely cold; in addition, Proxima Centauri is an active star, and its flares may occasionally send lethal X-rays to the planet; moreover, scientists still do not know the planet Whether it has a protective atmosphere capable of nurturing life.
Proxima Centauri is in the Alpha Centauri three-star system. In 2012, a Nature paper reported that another star in the three-star system, Alpha Centauri B2, had an Earth-mass planet, but the finding was later denied. But exoplanet experts say the Proxima planet is likely to exist.
Artie Hatzes, an astronomer at the Thuringia National Observatory in Germany, said: “Everyone calls me ‘Mr Sceptical’ because I often doubt the authenticity of many discoveries. But this time I think the planet Proxima Centauri It’s probably true.”
next steps
Anglada-Escudé said the new observations, along with older observations dating as far back as 2000, support the findings. “It’s been there for a long time, and the phase and magnitude of motion are regular,” said another team member, Michael Endl of the University of Texas at Austin. “It’s a clear sign of the presence of a planet.” The data even suggest that, Proxima Centauri may even have a second planet with a period between 100 and 400 days.
What the researchers now want to know is whether Proxima Centauri’s planet can be seen passing through the star’s surface from Earth’s direction. Although the probability is relatively low, if this “transit” phenomenon can be observed, details of the planet can be observed, such as whether it has an atmosphere and so on. A team led by Kipping is also independently looking for signs of planetary pass-by on Proxima Centauri’s surface, and they are nervously searching for any possible signs.
Steinn Sigurdsson, an astrophysicist at Penn State University City, believes that the discovery of Proxima Centauri’s planets coincides with scientists’ recent growing interest in smaller planets near dwarf planets. NASA’s Kepler space telescope has shown that rocky planets often surround such stars, which are themselves the most numerous stars in the Milky Way. “This finding completely confirms the correctness of this strategy,” he said.
The discovery of the planet Proxima Centauri may mark the birth of a new strategy for planetary research. “It gives us a target and center of gravity to build the next generation of telescopes and even be able to send spacecraft to probe later,” Kipping said. “This discovery comes at the right time to take exoplanet research to the next level. ”
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