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For me cause of format this one was just easier to read here. Though I was wondering, is that Ceti Alpha 5 and 6 there?
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At about 40 light-years (235 trillion miles) from Earth, the system of planets is relatively close to us, in the constellation Aquarius. Because they are located outside of our solar system, these planets are scientifically known as exoplanets.
This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system. Assisted by several ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
The new results were published Wednesday in the journal Nature, and announced at a news briefing at NASA Headquarters in Washington.
Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them, allowing their density to be estimated.
Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces. The mass of the seventh and farthest exoplanet has not yet been estimated – scientists believe it could be an icy, “snowball-like” world, but further observations are needed.
“The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star,” said Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium. “It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.”
In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.
The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.
Spitzer, an infrared telescope that trails Earth as it orbits the sun, was well-suited for studying TRAPPIST-1 because the star glows brightest in infrared light, whose wavelengths are longer than the eye can see. In the fall of 2016, Spitzer observed TRAPPIST-1 nearly continuously for 500 hours. Spitzer is uniquely positioned in its orbit to observe enough crossing – transits – of the planets in front of the host star to reveal the complex architecture of the system. Engineers optimized Spitzer’s ability to observe transiting planets during Spitzer’s “warm mission,” which began after the spacecraft’s coolant ran out as planned after the first five years of operations.
“This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena, California. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”
Following up on the Spitzer discovery, NASA’s Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone. These observations aim at assessing the presence of puffy, hydrogen-dominated atmospheres, typical for gaseous worlds like Neptune, around these planets.
This 360-degree panorama depicts the surface of a newly detected planet, TRAPPIST 1-d, part of a seven planet system some 40 light years away. Explore this artist’s rendering of an alien world by moving the view using your mouse or your mobile device.
In May 2016, the Hubble team observed the two innermost planets, and found no evidence for such puffy atmospheres. This strengthened the case that the planets closest to the star are rocky in nature.
“The TRAPPIST-1 system provides one of the best opportunities in the next decade to study the atmospheres around Earth-size planets,” said Nikole Lewis, co-leader of the Hubble study and astronomer at the Space Telescope Science Institute in Baltimore, Maryland. NASA’s planet-hunting Kepler space telescope also is studying the TRAPPIST-1 system, making measurements of the star’s minuscule changes in brightness due to transiting planets. Operating as the K2 mission, the spacecraft’s observations will allow astronomers to refine the properties of the known planets, as well as search for additional planets in the system. The K2 observations conclude in early March and will be made available on the public archive.
Spitzer, Hubble, and Kepler will help astronomers plan for follow-up studies using NASA’s upcoming James Webb Space Telescope, launching in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet’s atmosphere. Webb also will analyze planets’ temperatures and surface pressures – key factors in assessing their habitability.
NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate. Science operations are conducted at the Spitzer Science Center, at Caltech, in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at Caltech/IPAC. Caltech manages JPL for NASA.
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Seven Planets, Including Three Habitable Ones, Found Around Ultra-Cool Dwarf Star
Forty light-years away, a faint, dim, tiny star known as TRAPPIST-1 caught the fancy of a team of exoplanet hunters led by Michaël Gillon. By observing the starlight over long periods of time, they could tell when an orbiting planet passed in front of it, blocking a small fraction of its light in a periodic fashion. Only a small fraction of stars have their planets aligned in such a way that we can see them, and even fewer have rocky, Earth-like worlds at the right distance to potentially have liquid water — and life as we know it — on them. But this particular star, as scientist Brian Koberlein reports, was discovered to have seven planets orbiting it. Not only that, but three of them might be perfect for life.
The relative orbital sizes of the seven discovered planets. The two innermost ones are likely roasted, and the third is probably too hot for liquid water on its surface as well. But the next three, in the right spot in the habitable zone, might be more Earth-like than any worlds we’ve discovered before. Image credit: ESO/M. Gillon et al.In order to be habitable, at least habitable like Earth is, a world needs to be:
at the right distance from its star,
of the right mass,
with the right atmosphere,
and with the right amount of liquid water on its surface.While Earth is 150 million kilometers (93 million miles) away from the Sun, TRAPPIST-1 is only 8% the mass of the Sun, and gives off only 0.05% of the Sun’s energy. It would take more than 1900 stars like TRAPPIST-1 to equal the Sun.
This diagram compares the sizes of the newly-discovered planets around the faint red star TRAPPIST-1 with the Galilean moons of Jupiter and the inner Solar System. All the planets found around TRAPPIST-1 are of similar size to the Earth. Image credit: ESO/O. Furtak.
Yet at the same time, the seven worlds discovered to orbit TRAPPIST-1 are incredibly close in. They’re more comparable to the moons of Jupiter than they are to the planets in our Solar System as far as distances go. Yet that’s exactly what this system would need if it were to have any hope of liquid water on one of its worlds. As coauthor Amaury Triaud explains:
The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1!
The orbits of the Galilean moons around Jupiter, the seven planets discovered around TRAPPIST-1, and the inner Solar System worlds, shown together for comparison of scale. Image credit: ESO/O. Furtak.
The way we reconstruct how large each planet is comes from noticing how much light is blocked when it transits in front of the star. Seven unique, periodic signals were identified, with each one corresponding to a bona fide planet.
The data obtained for the transit depths of each of the seven planets around TRAPPIST-1. Data taken with the Spitzer Space Telescope. Image credit: ESO/M. Gillon et al.
Remarkably, each one of them is approximately the size of a world like ours, with many of them right around the size of Earth or Venus. They’re almost perfect: massive enough to hold onto a reasonably thick atmosphere, yet small enough to still be rocky, without a gaseous envelope.
Unlike the worlds in our Solar System, each one should be tidally locked to the parent star, meaning that the same side always sees “day” while the opposite side resides in eternal night. Yet life on Earth began in the oceans, and of these seven worlds, the fourth, fifth and sixth might all have conditions to support liquid oceans or lakes — if the atmosphere is favorable — bathed in eternal sunlight.
These worlds are also interesting because they’re substantially different from the worlds in our Solar System in some ways: they’re only about two-thirds as dense. While other solar systems we’ve found, mostly around more massive stars than TRAPPIST-1, have most of their worlds substantially smaller or larger than Earth, this system has seven worlds that are all approximately our size. As Michaël Gillon notes:
This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!
These worlds are also interesting because they’re substantially different from the worlds in our Solar System in some ways: they’re only about two-thirds as dense. While other solar systems we’ve found, mostly around more massive stars than TRAPPIST-1, have most of their worlds substantially smaller or larger than Earth, this system has seven worlds that are all approximately our size. As Michaël Gillon notes:
This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!
While the discovery of these seven planets is remarkable, the most interesting part of this story is yet to be written. As our telescopes become larger and more sophisticated, we’ll finally gain the ability to measure the spectra of these worlds’ atmospheres, search for signs of water and life, and perhaps even discover an answer to whether we’re not alone in the Universe as far as life goes. With three strong candidates, we might finally need to face the possibility that most of the life that arises in the Universe might occur around stars that aren’t like the Sun!
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