These are planets orbiting pulsars, and therefore for sure if they once had life on them they were already destroyed long ago
Avi Blizovsky
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Three extrasolar planets discovered so far are similar in size to Earth. They were already discovered over ten years ago, but due to disagreements, the discoveries have not yet been officially confirmed.
But today the debate is over. The planets are still there, and astronomers have been able to identify their sizes with greater precision.
These are dead worlds surrounding a dying planet, and there is absolutely no chance that anything interesting will happen there from a biological point of view. Because of this, most planet hunters show no interest in them. In fact, they are also ignored when making a list of planets outside the solar system. They are rarely mentioned even though they are actually the first planets discovered outside the solar system.
These three planets orbit a neutron star, a compressed star that was not far from becoming a black hole. Alex Volzchen of Pennsylvania State University discovered them in 1990.
One of the planets is 4.3 times more massive than Earth and another is 3 times heavier than Earth, plus or minus five percent. According to Volzchen and Klatec postdoctoral fellow Makia Konaki, who presented their findings at the American Astronomical Union meeting in Nashville. The measurements of the third planet are less precise, but it seems that its mass is twice that of the Moon - and significantly less than that of the Earth.
"It's reminiscent of our inner solar system," Konaki said.
Besides the lack of biology, there is another difference: that the outer planet of the three orbits the star in only 98 days, much less than Earth's 365 days. The researchers were able to identify the mass of the planets by observing the way in which the orbits of the planets affect the pulses of energy coming from the star. A neutron star rotates around itself at high speed and is also called a pulsar because it releases its energy in pulses. The pulsar is called PSR 1257+12.
Konaki said he studied the leads and lags in the pulses. The work will be published in detail in the Astrophysical Journal Letters.
All the other known planets orbiting other suns are this large - most of them tens of times the mass of Earth and they are supposed to be balls of gas, like Jupiter. Several teams of researchers will try using satellites to be launched in the next decade to locate Earth-like planets orbiting suns similar to ours, meaning the possibility of life, but no one can say now whether such planets exist.
The debate about the three planets stems from the fact that there is an observational limit and it is difficult to identify them, what's more, most of the claims for finding such planets before 1990 were rejected.
Dr. David Weintraub of Vanderbilt University says that there is no longer any debate about the existence of pulsar planets, but he added that he and others who study potential life places are not interested in dead worlds, no matter how big they are. "Astrophysically they are interesting and important but they are not relevant to the question The existence of life" concludes Weittentraub.
Know planets outside the solar system
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