The first exoplanet to be detected, orbiting a star like our own Sun, was discovered in 1995. Since that historic find almost a generation ago, exoplanet discoveries have come at a breakneck pace and, at the time of this writing, more 1,000 remote worlds orbiting remote stars have been confirmed. The search for a habitable planet, like our own world, remains the Holy Grail of dedicated planet hunters. In November 2013, astronomers from the University of California, Berkeley and the University of Hawaii, Manoa, reported their estimate that one in five Sun-like stars have Earth-size planets with surface temperatures favorable for the evolution of Earth. lifetime. Since about 20 percent of stars are like the Sun, this equates to several tens of trillions of potentially habitable Earth-size exoplanets in our Milky Way galaxy–only!
“When you look at the thousands of stars in the night sky, the closest Sun-like star with an Earth-size planet in its habitable zone is probably only 12 light-years away and can be seen with the naked eye. That’s right.” unbelievable,” commented Berkeley graduate student Erik Petigura in a November 4, 2013 Press release from the University of California, Berkeley. Mr. Petigura led the analysis of data derived from NASA Kepler Space Telescope that came to this impressive number of potentially habitable Earth-like worlds. Kepler sadly it is now at a standstill, with its four-year mission at a premature end. However, he still managed to provide enough valuable data to answer his main research question: How many of the 200 billion stars in our galaxy could host habitable planets?
“It has been almost 20 years since the discovery of the first extrasolar planet around a normal star. Since then, we have learned that most stars have planets of some size orbiting them, and that Earth-sized planets are relatively small. common in close orbits that are too hot for life,” Dr. Andrew Howard explained in the November 4, 2013 Berkeley press release. Dr. Howard, a former Berkeley Postdoctoral Fellow, is now on the faculty of the Institute for Astronomy at the University of Hawaii. “With this result, we have come home, in a sense, in showing that planets like our Earth are relatively common throughout the Milky Way,” he added.
Petagura, Howard, and Dr. Geoffrey W. Marcy, a Berkeley astronomy professor and one of the most successful planet hunters, published their analysis in November 2013 in the journal’s first online edition. Proceedings of the National Academy of Sciences.
Kepler revealed more than 3,500 candidate exoplanets in its first three years of operation, including small and large planets, rocky and gas planets, and a total of 647 potential planets that appear to be Earth-sized.
Also, in November 2013, an independent team of planet hunters, behind the Kepler Space Telescopeannounced that they had bagged another 833 potential exoplanets to consider adding to those already known.
This plethora of planets far exceeds what astronomers dreamed of before NASA’s launch Kepler in 2009. The telescope, which is in orbit around the Sun, discovers exoplanets by looking for them as they “transit,” that is, pass in front of the bright, fiery faces of their stellar parents. This transit causes a brief dimming of the light from the parent star. “When I started working with Kepler just before launch, I thought maybe there would be a thousand planets that Kepler would find,” said Dr. Jason Rowe at a press conference on November 4, 2013, held at the Kepler Science Conference at Moffett Field, Calif. Dr. Rowe is an astronomer at the SETI Institute (Search for Extraterrestrial Intelligence) in Mountain View, Calif.
“We are discovering that there is a wide variety of systems. If you can imagine it, the Universe probably does,” Dr Rowe added.
The best chance of finding life as we know it, living on distant worlds around other stars, is to look for habitable environments that share the comfortable, life-friendly attributes of our beautiful planet: protective atmospheres, rocky compositions, the right amount of star friendly–glitter, and plenty of water in its life-loving liquid phase. Astronomers define the living area around a star like range of distances, based on temperature, that is most likely to possess such a delicious plate of perfect “Goldilocks” offerings. so far, Kepler has detected 104 potential exoplanets likely to inhabit this “Goldilocks” region around their stars, 10 of which are less than twice the radius of our own planet. However, to find out if these distant alien worlds really do have what it takes to spawn a batch of living things, follow-up observations from the next generation of telescopes will be needed.
Forty billion worlds!
The Berkeley team warned that Earth-size planets in “Goldilocks” orbits are not necessarily havens for life. This is because, even if such planets rotate within the living areas of their stars, “Some may have thick atmospheres, making the surface so hot that DNA-like molecules would not survive. Others may have rocky surfaces that could harbor liquid water suitable for living organisms. We don’t know what range of types of planets and their environments are suitable for life,” explained Dr. Marcy in the November 4, 2013 Berkeley press release.
Mr. Petagura’s analysis, however, is a giant step towards achieving the main objective of the Kepler mission: to measure the percentage of stars similar to the Sun, that inhabit our Milky Way, that have descendants of planets the size of the Earth. sometimes referred to Earth Etais an important factor in Drake equation. Tea drake equation is used to estimate the number of intelligent civilizations that could be partying in our galaxy.
“For NASA, this discovery is really important, because future missions will try to take a real picture of a planet, and the size of the telescope they have to build depends on how close the nearest Earth-sized planets are. abundance of planets orbiting nearby stars simplifies such follow-up missions,” continued Dr. Howard in the November 4, 2013 Berkeley press release.
In October 2013, Dr. Marcy, Dr. Howard, and their colleagues offered hope that many life-friendly Earth-type exoplanets detected by Kepler they are actually rocky, life-friendly worlds that could harbor beautiful oceans of precious liquid water. They reported that an Earth-sized planet, a roaster with a surface temperature of 2,000 Kelvin, and too hot for life as we know it, has about the same density as our own planet and is likely composed of rock and iron. like our own world.
“This gives us some confidence that when we look outward habitable zone, the planets that Erik (Petagura) is describing may be rocky planets the size of Earth,” Dr. Howard continued in the November 4, 2013, Berkeley press release.
Many of the thousands of alien worlds that were discovered by Kepler they are considerably larger than our own small planet, and range from planets with dense atmospheres, like Neptune, to giant planets with extremely thick gaseous envelopes, like Jupiter and Saturn. Some also spin in fast, close orbits that hug their parent stars so closely that they literally roast under their fiery stellar heat.
To solve this abundance of brave new worlds, Mr. Petagura and his team used the two Keck Telescopes in Hawaii to collect spectra of as many stars as possible. This allowed them to calculate the actual brightness of each star and determine the diameter of each transiting exoplanet, paying particular attention to those of similar size to Earth.
Mr. Petagura, Dr. Howard, and Dr. Marcy focused on 42,000 stars that are like our own Sun or just slightly cooler and smaller. They found 603 exoplanet candidates surrounding them. Only 10 of these were similar to Earth in size, that is, they were one or two times the diameter of our own planet, and they surrounded their stellar parent at that “Goldilocks” distance where they were warmed to a wonderfully comfortable temperature. . The team’s definition of what constitutes habitable it is a world that is endowed with between four and a quarter times the amount of starlight that Earth receives from its own Star, the Sun.
What distinguishes the study by Mr. Petagura’s team from previous analyzes of Kepler The information is that they put Mr. Petagura’s planet-finding algorithms through a lot of testing to determine how many Earth-size, living area, exoplanets they missed. Mr. Petagura actually introduced fake exoplanets into the Kepler data to calculate which ones your software could package and which ones it couldn’t.
“What we’re doing is doing a census of extrasolar planets, but we can’t knock on every door. Only after injecting these fake planets and measuring how many we actually find will we be able to really pin down how many real planets we missed.” “, noted Mr. Petagura on November 4, 2013 Berkeley press release.
Taking into account the overlooked planets, as well as the fact that only a small percentage of exoplanets are oriented in a way that transit facing the dazzling face of its parent star as seen from Earth, allowed the team to calculate that 22 percent of all stars like our own Sun, which inhabit our Milky Way, have Earth-sized exoplanets inhabiting their living areas.
All potentially habitable candidate planets found in the team’s survey are circled k class stars, which are slightly smaller and cooler than our Star. However, the astronomers’ analysis reveals that the result for k The stars can be extrapolated to GRAM class stars, like our Sun. It had Kepler Had it not met its untimely and tragic end, it would have gathered enough data to directly detect a handful of Earth-dwelling exoplanets within Earth. living areas from GRAM class stars.
In January 2013, the team reported a similar analysis of Kepler data from hot exoplanets hugging their stellar parents. This most recent and comprehensive analysis reveals that “nature produces as many planets in hospitable orbits as in close orbits,” said Dr. Howard in the November 4, 2013. Berkeley press release.