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Will there be habitable planets in the Alpha Centauri galaxy, our nearest star system? Scientists have struggled to answer this question for years, trying to look for signs of planets orbiting them through the glare of alpha centauri alpha A and B, two sun-like stars. The third member of the system, Proxima Centauri, is a red dwarf that is known to hold at least one planet.
Finding planets in alpha Centauri galaxy will bring huge scientific rewards. Because these stars are so close to us, a little more than four light-years away, that's just a stone's throw away in the universe, like on our "doorstep." Any planet in alpha Centauri galaxy would be the main target for future research, with terrestrial planets that may have life in particular. Now, a group of scientists plan to use privately funded telescopes to improve our understanding of Alpha Centauri, a method that has never been used before. "We now have this unprecedented opportunity to look for planets in this system that are in habitable zones." Olivier Guyon, from the University of Arizona, said he was part of the telescope team.
The team announced on November 16, 2021, that they had secured more than $500,000 in funding from the Australian government to continue developing the relatively low-cost telescope, Toliman. The telescope project was led by Peter Tuthill of the University of Sydney (Peter Tuthill and his colleagues first proposed the Toliman concept a few years ago, having previously received funding from NASA's Jet Propulsion Laboratory (JPL), Australian space engineering company Saber Astronautics, and the California Breakthrough Program, funded by tech billionaire Yuri Milner Initiatives) support. This small shoebox-sized telescope is specially designed to search for planets in alpha Centauri galaxy— particularly in its habitable zone (the habitable zone is an area warmed by the star's light that allows liquid water to exist on the surface of a rocky planet). It will do this in a way that no other telescope can match. The team's goal is to complete the construction of the telescope and launch it into Earth orbit by 2023, ready to begin its search in space. "It's fantastic to see private foundations facilitating our search for a 'nother planet.'" Sara Seager, from the Massachusetts Institute of Technology, said she was a "planet hunter" unrelated to the project.
In search of planets in the Alpha Centauri galaxy, many efforts have been made and varying degrees of success have been made. In 2012, scientists thought they had discovered a planet orbiting Alpha Centauri B, Alpha Centauri Bb, but in 2015, other researchers appeared to rule out the planet's existence. The investigation of Proxima Centauri was more fruitful, finding a possible Earth-sized planet , Proxima B , while suggesting the existence of another planet , Proxima Centauri c. In early 2021, scientists discovered a possible planet orbiting Alpha Centauri A, which is about the size of Neptune.
"Toliman" is an ancient Arabic name for Alpha Centauri and also stands for the Astronomical Neighborhood Orbital Trajectory Interference Monitoring Telescope (TOLIMAN is an abbreviation for Telescope for Orbit Locus Interferometric Monitoring of our Astronomical Neighborhood), which is designed to search for planets around Alpha Centauri A and B. Tuthill said some parts of the Toliman telescope have been contracted to begin construction, while Toliboy, a pioneering mission to test the technology, was launched to the International Space Station via the CUAVA-1 satellite earlier in 2021. Tuthill said the University of Sydney had been conducting lab testing and simulation work on Toliman's technology, while the team was currently working on a prototype in its original size. Although the mission still has some details that have not yet been determined, such as the rocket that launched it and its position in Earth's orbit, the technology itself is largely ready. "The components of this telescope involve quite mature technology, and they can be made today." Guyon said he is the chairman of the Breakthrough Watch project, which aims to search for planets around Alpha Centauri and other nearby stars.
The telescope primarily uses the binary nature of Alpha Centauri alpha and B to detect planets in their habitable zones, which are slightly farther between Uranus and the Sun. Tuthill said the telescope will use a technique called diffractive pupil, a transformative approach that employs optical techniques. The 12-centimeter-wide telescope will not be used to take high-resolution images of stars, but instead will disperse light from stars into thousands of pixels, creating a complex pattern from which "photon fingerprints" showing each star's spatial position can be seen. Scientists hope to find tiny changes in the star's position caused by the planet's gravity from this data. With two stars present, the task, called astrometry, would be easier to carry out than with just one star, because the distance between the two stars can be measured more accurately. Tuthill said: "Centaur Alpha star is very suitable for detection with this technology, it is like a specially arranged target for this mission. ”
Using Toliman's two years of astrometry data, the researchers should be able to confirm the existence of planets within the habitable zone of Alpha Centauri A or B ( that is , a range similar to the distance from Earth 's orbit ) . Astronomers can accurately measure the mass of each newly discovered planet by assessing their gravitational attraction to the star, which is the strength of astrometry. Most other planetary exploration techniques can only roughly estimate the mass of a planet, unable to distinguish a gas-shrouded "mini-Neptune" from a more Earth-like rocky planet. However, there are some minor shortcomings in this technology, such as if a planet is discovered, Toliman can't initially figure out which of the two stars it orbits. But we will almost certainly know whether there are any potentially habitable planets in this system that are comparable to earth's mass. Tuthill said: "We can identify planets in the habitable zone that are comparable to the mass of Earth. At the same time, he hopes that their discoveries will trigger a "gold rush" that will allow more people to join in and use more sophisticated methods to find habitable planets.
The Toliman mission heralds two interesting changes in exoplanet science. The first is the use of private funding for space science research that does not guarantee success, rather than relying solely on the support of the space agency and other government agencies. Guyon said: "A high-risk mission like this is difficult to be funded by public funding agencies because there is a possibility that there will be no planets in the Alpha Centauri system. "But the potential rewards of this type of mission are enormous." Once found, we knew that the nearest star system had a potentially habitable planet, which would revolutionize the plans of agencies. Guyon said. The project also marks a shift — from searching for thousands of exoplanets, as has been the case in the past 20 years, to conducting detailed studies of certain star systems. "The trend right now is to look for a large number of planets, but some of us are ready to focus on individual star systems," Seager said. ”
Emily Rickman of the Space Telescope Science Institute in Baltimore noted that the Toliman telescope's technology is exciting given the proximity of Alpha Centauri's star to Earth. "Finding any signs of extraterrestrial life in our 'backyard' on Earth would be a big deal," she said. "Even if Toliman hadn't detected anything, the mission would have deepened our understanding of Alpha Centauri." If nothing is found, either there is something very small that we can't see close to the stars, or there is nothing around those stars. It will be an interesting and valuable outcome, she said. Tuthill proposed that the Toliman telescope could also be used to detect other nearby binary systems, such as Cygnus 61, 11 light-years away, after detecting Alpha Centauri. But other star systems are not close enough for Toliman to provide that much precision, so it can only probe larger, potentially uninhabitable planets. Tuthill hopes to detect planets with larger masses than Earth or Neptune-like planets when probing other star systems.
For now, however, Alpha Centauri is the main target and has the potential to bring about major discoveries. In just a few years, we might know if there are one or more potentially habitable planets of Earth's mass, so close that we can not only study them with telescopes, but also potentially launch probes to explore them in the field. Such proposals have been made, including Breakthrough Watch's more high-profile sister project, Breakthrough Starshot, which is also one of the breakthrough projects to launch a miniature spacecraft at about one-tenth the speed of light to Alpha Centauri. Toliman will provide critical data for such a mission that will last for decades. Pete Worden, executive director of the Breakthrough Program, said: "We know that there is at least one planet in this star system, Proxima B, and if we finally confirm that Alpha Centauri A and B have no potential, life-bearing planets, then I might focus on Proxima Centauri." "If everything goes according to plan, we may find something out very quickly."
Written by Jonathan O'Callaghan
Translator: Wu Yujia
Reviewer: Zheng Yuhong
Source of introduction: Scientific American
This article is from: China Digital Science and Technology Museum