Astronomers have discovered a star system 39 light years away with several earth-like planets.
TRAPPIST-1 is a red dwarf star 39 light years away and has just become a promising candidate in the search for extra terrestrial life. Researchers have discovered that the star has seven planets orbiting around it, all roughly the size of earth. Three of the planets are in the star’s habitable zone, where temperatures hover between 0 and 100 degrees Celsius and liquid water can exist on the surface. All seven could potentially hold life.
The star first became known to ESA astronomers last year, who discovered it using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) telescope. At the time, they only knew of three planets in the system, but the astronomers studied the system in more detail using NASA’s Spitzer Space Telescope and the ESO’s Very Large Telescope, and the number has now more than doubled, to seven. Of them, six are considered to be rocky planets, and all could contain oceans of liquid water. The findings have been published in a paper submitted to Nature.
“All of these planets are the best targets found so far to search for signs of life in the next decade, and it is remarkable that they are all transiting the same star,” said co-author and MIT planetary scientist Julien de Wit. “This means that the system will allow us to study each planet in great depth, providing for the first time a rich perspective on a different planetary system than ours.”
Red dwarf stars are much smaller than our own sun, and as such, planets tend to orbit closer. TRAPPIST-1 has a surface temperature of around 2,550 Kelvin compared to 3,800 Kelvin for other red dwarfs and a scorching 5,800 Kelvin for our sun. As such, the habitable zone is much nearer to the star than it is in our solar system. The star system is, in fact, reminiscent of Jupiter’s planetary system. TRAPPIST-1 is only slightly larger than our largest planet, and the worlds surrounding it are roughly at the distances where Jupiter’s moons can be found. They’re so close to each other that one could clearly make out neighboring planets, according to NASA: “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.”
A potential drawback with living near a red dwarf is that planets tend to become tidally locked due to their proximity to the star. This is the same effect we see on Earth’s moon, whose rotational and orbital periods are synced, leaving one side always facing the earth, and one side always facing away. This would mean that some of TRAPPIST-1’s planets have one half of the planet trapped in perpetual daylight, with the other in an endless night. Such conditions can understandably lead to temperature extremes, but also to intense winds as heat flux travels around the planet.
At this point, we know very little about the planets surrounding the red dwarf. We can detect exoplanets by studying the brightness of their stars – when the planets transition in front of the star, it blocks some of the light, resulting in a dip in brightness. The intensity of this dip allows us to learn about the planet’s size, distance from the host star, and even its orbital period. Unfortunately, it is difficult to discern things like surface conditions or geology. With continued study however, and new technology, such as employing techniques like spectroscopy to study the atmosphere, we can learn much more.
“We can expect that, within a few years, we will know a lot more about these planets, and with hope, if there is life there, [we’ll know] within a decade,” said another co-author, Amaury Triaud, of the Institute of Astronomy at the University of Cambridge in England.