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Rogue Planets Could be Habitable

The search for potentially habitable planets is focused on exoplanets—planets orbiting other stars—for good reason. The only planet we know of with life is Earth and sunlight fuels life here. But some estimates say there are many more rogue planets roaming through space, not bound to or warmed by any star.

Could some of them support life?

The term ‘Rogue Planet’ is a colourful term used to describe what are actually interstellar objects (ISOs). But in the case of rogue planets, the ISOs are planetary-mass objects, rather than less massive objects like ‘Oumuamua or 2I/Borisov, the only two confirmed ISOs to enter our Solar System.

Rogue Planets have been somehow ejected from their solar systems. Young solar systems are chaotic places, where bodies collide with each other and where migrating gas giants can perturb smaller terrestrial planets from their orbits, sending them on an interstellar journey. It’s also possible that rogue planets form in interstellar space similar to how stars form. A planet could coalesce out of a cloud of gas and dust, along with a system of moons orbiting it. Sub-brown dwarfs are also considered rogue planets, but since they’re just gas, life is unlikely. In any case, rogue planets aren’t gravitationally bound to any star or stars. They’re free-floating.

We don’t know how many of them there are. If you ask Neil deGrasse Tyson there are billions of them in the Milky Way, maybe even trillions. Could any of them host life? Possibly.

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A star just 35 light-years away has been found to host a number of rocky exoplanets, and one that has a good chance of habitability.

Around the red dwarf L 98-59 orbit at least four planets, and the system looks to be fascinating. New observations confirm what prior research had already suggested – the existence of a terrestrial world with half the mass of Venus.

But the new observations also reveal new worlds in the same system, including an ocean planet, and what seems to be a super-Earth bang in the middle of the star's habitable zone.

"The planet in the habitable zone may have an atmosphere that could protect and support life," said astrophysicist María Rosa Zapatero Osorio of the Centre for Astrobiology in Spain.

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A new scientific report suggests that there are 29 planets in our cosmic neighbourhood where alien life could potentially see and hear evidence of humans on Earth, based on humanity’s own techniques for studying the universe.

The report was published Wednesday by two New York-based astronomers in the journal Nature, in an effort to narrow down our own search for alien life among the stars. It doesn’t attempt to prove that anyone is actually out there listening, or that they’d want to hear from us if they were. The report simply tries to determine where our most likely alien audiences would be.

The authors assume that aliens would be able to spot Earth by seeing its faint shadow as it transits in front of the sun — a technique that we’ve used to find many Earth-like worlds to date.

“One way we find planets is if they block out part of the light from their host star,” Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University and co-author of the article, told The Guardian. “We asked, ‘Who would we be the aliens for, if somebody else was looking?’ There is this tiny sliver in the sky where other star systems have a cosmic front seat to find Earth as a transiting planet.”

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Exoplanet discoveries used to be nothing but a dream for scientists, but new telescope technology and more advanced observation techniques have made the task of finding planets outside of our solar system easier than ever. In fact, so many new exoplanets are being found these days that scientists have to pick and choose which ones are most in need of study since there simply aren’t enough eyes to go around.

Now, a massive international team of astronomers and other scientists have revealed the discovery of a particularly interesting exoplanet that is sure to get a lot of attention. It’s called TOI-1231b, and it orbits a star much cooler than our own Sun. The star, named NLTT 24399, is a red dwarf, so despite TOI-1231b being much closer to its star than Earth is to the Sun, the planet is actually similar in temperature, and it is thought to have a robust atmosphere that warrants future study.

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The Hubble Space Telescope has peered out into the cosmos and spotted its youngest exoplanet yet, a giant world 379 light-years from Earth that's still growing.

Planets form as dust and gas, swirling around in a circumstellar disk surrounding their star, collides and condenses to slowly become a "ball." Far out in the constellation Centaurus, Hubble has spotted a planet still coming together. The young gas giant exoplanet, designated PDS 70b, is "just" 5 million years old, Hubble scientists said. While the planet is still gathering mass, pulling it from the young star it orbits, it's already huge — roughly the size of Jupiter.

In a new study, scientists took advantage of this unique opportunity to study a planet in its formative years like PDS 70b with Hubble's telescope eye.

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In recent years there has been an exhaustive study of red dwarf stars to find exoplanets in orbit around them. These stars have effective surface temperatures between 2400 and 3700 K (over 2000 degrees cooler than the Sun), and masses between 0.08 and 0.45 solar masses. In this context, a team of researchers led by Borja Toledo Padrón, a Severo Ochoa-La Caixa doctoral student at the Instituto de Astrofísica de Canarias (IAC), specializing in the search for planets around this type of stars, has discovered a super-Earth orbiting the star GJ 740, a red dwarf star situated some 36 light years from the Earth.

The planet orbits its star with a period of 2.4 days and its mass is around 3 times the mass of the Earth. Because the star is so close to the Sun, and the planet so close to the star, this new super-Earth could be the object of future researches with very large diameter telescopes towards the end of this decade. The results of the study were recently published in the journal Astronomy & Astrophysics.

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This artist's concept is of a Jupiter-mass planet orbiting the nearby star Epsilon Eridani. Located 10.5 light-years away, it is the closest known exoplanet to our solar system. The planet is in an elliptical orbit that carries it as close to the star as Earth is from the Sun, and as far from the star as Jupiter is from the Sun.

Epsilon Eridandi is a young star, only 800 million years old. It is still surrounded by a disk of dust that extends 20 billion miles from the star. The disk appears as a linear sheet of reflecting dust in this view because it is seen edge-on from the planet's orbit, which is in the same plane as the dust disk.

The planet's rings and satellites are purely hypothetical in this view, but plausible. As a gas giant, the planet is uninhabitable for life as we know it. However, any moons might have conditions suitable for life.

Astronomers determined the planet's mass and orbital tilt in 2006 by using Hubble to measure the unseen planet's gravitational pull on the star as it slowly moved across the sky. Evidence for the planet first appeared in 2000 when astronomers measured a telltale wobble in the star.

Source: nasa.gov

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The nearest solar system to our own may actually host two potentially life-supporting planets, a new study reports.

In 2016, scientists discovered a roughly Earth-size world circling Proxima Centauri, part of the three-star Alpha Centauri system, which lies about 4.37 light-years from Earth. The planet, known as Proxima b, orbits in the "habitable zone," the range of distances from a star at which liquid water could exist on a world's surface. (A second planet, Proxima c, was later discovered circling the star as well, but it orbits farther away, beyond the habitable zone's outer limits.)

There's considerable debate about the true habitability of Proxima b, however, given that its parent star is a red dwarf. These stars, the most common in the Milky Way, are small and dim, so their habitable zones lie very close in — so close, in fact, that planets residing there tend to be tidally locked, always showing the same face to their host stars, just as the moon always shows Earth its near side. In addition, red dwarfs are prolific flarers, especially when they're young, so it's unclear if their habitable-zone worlds can hold onto their atmospheres for long.

The other two stars in the Alpha Centauri trio, however, are sunlike — a pair called Alpha Centauri A and B, which together make up a binary orbiting the same center of mass. And Alpha Centauri A may have its own habitable-zone planet, according to the new research, which was published online today (Feb. 10) in the journal Nature Communications.

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