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New research using data collected by the European Southern Observatory (ESO) has revealed that a little-known exoplanet called K2-18b could well be a scaled-up version of Earth.
Just as exciting, the same researchers also discovered for the first time that the planet has a neighbor.
"Being able to measure the mass and density of K2-18b was tremendous, but to discover a new exoplanet was lucky and equally exciting," says lead author Ryan Cloutier, a PhD student in U of T Scarborough's Centre for Planet Science, U of T's Department of Astronomy and Astrophysics, and Université de Montréal Institute for research on exoplanets (iREx).
Both planets orbit K2-18, a red-dwarf star located about 111 light years away in the constellation Leo. When the planet K2-18b was first discovered in 2015, it was found to be orbiting within the star's habitable zone, making it an ideal candidate to have liquid surface water, a key element in harbouring conditions for life as we know it.
The data set used by the researchers came from the High Accuracy Radial Velocity Planet Searcher (HARPS) using the ESO's 3.6m telescope at La Silla Observatory, in Chile. HARPS allows for measurements of radial velocities of stars, which are affected by the presence of planets, to be taken with the highest accuracy currently available. Hence, this instrument allows for the detection of very small planets around them.
In order to figure out whether K2-18b was a scaled-up version of Earth (mostly rock), or a scaled-down version of Neptune (mostly gas), researchers had to first figure out the planet's mass, using radial velocity measurements taken with HARPS.
"If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of," says Cloutier.
After using a machine-learning approach to figure out the mass measurement, Cloutier and his team were able to determine the planet is either a mostly rocky planet with a small gaseous atmosphere – like Earth, but bigger – or a mostly water planet with a thick layer of ice on top of it.
"With the current data, we can't distinguish between those two possibilities," he says. "But with the James Webb Space Telescope (JWST) we can probe the atmosphere and see whether it has an extensive atmosphere or it's a planet covered in water."
The bright M dwarf K2-18 at 34 pc is known to host a transiting super-Earth-sized planet orbiting within the star's habitable zone; K2-18b. Given the superlative nature of this system for studying an exoplanetary atmosphere receiving similar levels of insolation as the Earth, we aim to characterize the planet's mass which is required to interpret atmospheric properties and infer the planet's bulk composition. We obtain precision radial velocity measurements with the HARPS spectrograph and couple those measurements with the K2 photometry to jointly model the observed radial velocity variation with planetary signals and a radial velocity jitter model based on Gaussian process regression. We measure the mass of K2-18b to be 8.0±1.9 M⊕ with a bulk density of 3.7±0.9 g/cm3 which may correspond to a predominantly rocky planet with a significant gaseous envelope or an ocean planet with a water mass fraction ≳50%. We also find strong evidence for a second, warm super-Earth K2-18c at ∼9 days with a semi-major axis 2.4 times smaller than the transiting K2-18b. After re-analyzing the available light curves of K2-18 we conclude that K2-18c is not detected in transit and therefore likely has an orbit that is non-coplanar with K2-18b. A suite of dynamical integrations with varying simulated orbital eccentricities of the two planets are used to further constrain each planet's eccentricity posterior from which we measure eb<0.43 and ec<0.47 at 99% confidence. The discovery of the inner planet K2-18c further emphasizes the prevalence of multi-planet systems around M dwarfs. The characterization of the density of K2-18b reveals that the planet likely has a thick gaseous envelope which along with its proximity to the Solar system makes the K2-18 planetary system an interesting target for the atmospheric study of an exoplanet receiving Earth-like insolation.
Two super-Earths around star K2-18
December 5, 2017
New research using data collected by the European Southern Observatory (ESO) has revealed that a little-known exoplanet called K2-18b could well be a scaled-up version of Earth.
Just as exciting, the same researchers also discovered for the first time that the planet has a neighbor.
"Being able to measure the mass and density of K2-18b was tremendous, but to discover a new exoplanet was lucky and equally exciting," says lead author Ryan Cloutier, a PhD student in U of T Scarborough's Centre for Planet Science, U of T's Department of Astronomy and Astrophysics, and Université de Montréal Institute for research on exoplanets (iREx).
Both planets orbit K2-18, a red-dwarf star located about 111 light years away in the constellation Leo. When the planet K2-18b was first discovered in 2015, it was found to be orbiting within the star's habitable zone, making it an ideal candidate to have liquid surface water, a key element in harbouring conditions for life as we know it.
The data set used by the researchers came from the High Accuracy Radial Velocity Planet Searcher (HARPS) using the ESO's 3.6m telescope at La Silla Observatory, in Chile. HARPS allows for measurements of radial velocities of stars, which are affected by the presence of planets, to be taken with the highest accuracy currently available. Hence, this instrument allows for the detection of very small planets around them.
In order to figure out whether K2-18b was a scaled-up version of Earth (mostly rock), or a scaled-down version of Neptune (mostly gas), researchers had to first figure out the planet's mass, using radial velocity measurements taken with HARPS.
"If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of," says Cloutier.
After using a machine-learning approach to figure out the mass measurement, Cloutier and his team were able to determine the planet is either a mostly rocky planet with a small gaseous atmosphere – like Earth, but bigger – or a mostly water planet with a thick layer of ice on top of it.
"With the current data, we can't distinguish between those two possibilities," he says. "But with the James Webb Space Telescope (JWST) we can probe the atmosphere and see whether it has an extensive atmosphere or it's a planet covered in water."
Read more at: https://phys.org/new...ar-k2-.html#jCp
There's so many choices!!! Can't wait until the james web is up in running!
Send Starfleet ahead to remove klingons.
Wouldn't a scaled up earth have a much stronger gravity?
Wouldn't a scaled up earth have a much stronger gravity?
Yes, so life there would adapt by being built smaller and closer to the ground. A non-obese human could probably live on one but it would be an exhausting 24/7 workout.
Wouldn't a scaled up earth have a much stronger gravity?
Yes, so life there would adapt by being built smaller and closer to the ground. A non-obese human could probably live on one but it would be an exhausting 24/7 workout.
Yes, people could adapt, especially with the aid of technology. But no crops or livestock would be able to survive. Which means all food would have to be transported in from great distances.
Wouldn't a scaled up earth have a much stronger gravity?
Yes, so life there would adapt by being built smaller and closer to the ground. A non-obese human could probably live on one but it would be an exhausting 24/7 workout.
Yes, people could adapt, especially with the aid of technology. But no crops or livestock would be able to survive. Which means all food would have to be transported in from great distances.
Who's to say one way or the other whether life could survive on this world.
Two super-Earths around star K2-18
December 5, 2017
New research using data collected by the European Southern Observatory (ESO) has revealed that a little-known exoplanet called K2-18b could well be a scaled-up version of Earth.
Just as exciting, the same researchers also discovered for the first time that the planet has a neighbor.
"Being able to measure the mass and density of K2-18b was tremendous, but to discover a new exoplanet was lucky and equally exciting," says lead author Ryan Cloutier, a PhD student in U of T Scarborough's Centre for Planet Science, U of T's Department of Astronomy and Astrophysics, and Université de Montréal Institute for research on exoplanets (iREx).
Both planets orbit K2-18, a red-dwarf star located about 111 light years away in the constellation Leo. When the planet K2-18b was first discovered in 2015, it was found to be orbiting within the star's habitable zone, making it an ideal candidate to have liquid surface water, a key element in harbouring conditions for life as we know it.
The data set used by the researchers came from the High Accuracy Radial Velocity Planet Searcher (HARPS) using the ESO's 3.6m telescope at La Silla Observatory, in Chile. HARPS allows for measurements of radial velocities of stars, which are affected by the presence of planets, to be taken with the highest accuracy currently available. Hence, this instrument allows for the detection of very small planets around them.
In order to figure out whether K2-18b was a scaled-up version of Earth (mostly rock), or a scaled-down version of Neptune (mostly gas), researchers had to first figure out the planet's mass, using radial velocity measurements taken with HARPS.
"If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of," says Cloutier.
After using a machine-learning approach to figure out the mass measurement, Cloutier and his team were able to determine the planet is either a mostly rocky planet with a small gaseous atmosphere – like Earth, but bigger – or a mostly water planet with a thick layer of ice on top of it.
"With the current data, we can't distinguish between those two possibilities," he says. "But with the James Webb Space Telescope (JWST) we can probe the atmosphere and see whether it has an extensive atmosphere or it's a planet covered in water."
Read more at: https://phys.org/new...ar-k2-.html#jCp
There's so many choices!!! Can't wait until the james web is up in running!
Wouldn't a scaled up earth have a much stronger gravity?
Yes, so life there would adapt by being built smaller and closer to the ground. A non-obese human could probably live on one but it would be an exhausting 24/7 workout.
Yes, people could adapt, especially with the aid of technology. But no crops or livestock would be able to survive. Which means all food would have to be transported in from great distances.
Who's to say one way or the other whether life could survive on this world.
A biologist? Livestock do not adapt as quickly. Neither do crops. The higher gravity would have a profound effect on both.
Wouldn't a scaled up earth have a much stronger gravity?
Yes, so life there would adapt by being built smaller and closer to the ground. A non-obese human could probably live on one but it would be an exhausting 24/7 workout.
Yes, people could adapt, especially with the aid of technology. But no crops or livestock would be able to survive. Which means all food would have to be transported in from great distances.
