The first exoplanet, a planet outside our Solar System, was first discovered by a European team in 1995. Today, an international team released a report that they found two 'super Earth' exoplanets that may be habitable.
The evolution and stability of an exoplanet are affected by its gravitational interaction with other objects orbiting the same star. As the team of scientists was monitoring the red dwarf star Gliese 887 (GJ 887), they noticed two planets orbiting it 'just within the habitable zone.' Since the pair of planets are orbiting within the inner edge of the habitable zone, they may be too hot for life to thrive or for liquid water to remains on the.
Using a planet-finding telescope from the European Southern Observatory in La Silla, Chile, the team comprised of Australian astronomers and the international Red Dots team. Red Dots' goal is to detect the nearest terrestrial planets to the Sun. These exoplanets typically orbit around nearby red dwarf stars where they use the Doppler spectroscopy method.
Two Super Earths
Planet GJ 887b and GJ887c may be 'rocky worlds' similar to Earth's surface but the team predicts that they are tidally locked, meaning that only one side is always facing its star, making that side constantly daytime and the opposite side nighttime.
Dr. John Barnes, an astrophysicist at the Open University, said, 'Close orbiting planets like these have a high chance of being tidally locked to their host star. This means that as the planet orbits its star, the same hemisphere always faces the star.'
Using the Doppler wobble method find the exoplanets and measure their gravitational relationship with GJ 887, the start would wobble slightly as the pair would orbit. They also observed that the wobble affects the star's light as well.
GJ 887c's proximity to its parent star gives it an estimated temperature of 158 degrees Fahrenheit on the surface as it takes almost 22 days to circle the star. GJ 887b, which is closer to its host star with a 9.3-day orbit, is most likely to have higher surface temperatures. Since only half of each planet is facing the star, ' it could be much cooler on some parts of the planets than others,' explained Dr. Barnes.
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The Habitable Zone
Since the GJ 887 is not as active as other red dwarfs, the two planets might not have strong stellar winds, which is material from the star causing orbiting planet atmospheres to erode. The team hopes to find a third habitable planet from an unconfirmed signal they detected. They are still unable to confirm if the signal may be another exoplanet because 'if the signal is a planet, it would orbit every 51 days,' said Dr. Barnes.
The Red Dots team was excited to discover that GJ 887 has fewer starspots compared to the Sun, meaning that the exoplanets' atmospheres are less eroded than Earth's. The thicker atmospheres increase the chances of making it a habitable planet.
Dr. O'Toole from the Macquerie University said, 'In the era of space-based exoplanet-hunting telescopeslike NASA's Kepler and TESS, this result shows that astronomy from the ground continues to play a crucial role in our understanding of planets in our local neighborhood.' Professor Chris Tinney also shared that 'Planets orbiting nearby stars are key for searches with future telescopes for both explanatory atmospheres and eventually evidence for life.'
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