Astronomers have found a new exoplanet codenamed HD 20782 with the most eccentric orbit noticed till date. The exoplanet is 117 light years away from earth. A team of researchers from San Francisco State University has found exoplanet HD 20782 with eccentricity rating of 0.96. The exoplanet moves in an almost completely flattened ellipse. It then makes a highly-energetic, high-speed slingshot around its sun on the closest approach.
Astronomers have discovered many exoplanets with highly elliptical orbits. Planets in our solar system have very low eccentricity rating for their orbits. HD 20782 faces blistering exposure to its star for a short while as it comes quite close, for a brief period.
At the furthest point in its orbit, HD 20782 is separated from its star by 2.5 times the distance between the Earth and Sun. At the closest point HD 20782 is just 0.06 of the distance between the Earth and Sun.
Findings of the research team from San Francisco State University have been published in the Astrophysical Journal.
Researchers were able to confirm its extreme eccentricity and the rest of its orbital parameters as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS), a project led by Kane to detect extrasolar planets as they pass in front of their stars.
Using these new parameters to time their observations, scientists also used a satellite-based telescope to collect light data from the planet as it orbited closest to its star.
They were able to detect a change in brightness that appears to be a signal of reflected light bouncing off the planet’s atmosphere.
The reflected light could tell researchers more about how the atmosphere of a planet like HD 20782 responds when it spends most of its time far away from its star, “but then has a very close approach where it’s flash-heated by the star,” said Kane.
“It’s around the mass of Jupiter, but it’s swinging around its star like it’s a comet,” said Kane, an assistant professor of physics and astronomy at the university. While previous observations of the planet suggested that it had a highly eccentric orbit, Kane’s team confirmed that fact as part of their work on the Transit Ephemeris Refinement and Monitoring Survey (TERMS), a project designed to detect exoplanets as they pass in front of their host stars.
They were also able to determine the planet’s other orbital parameters, and using this data, they were able to observe the planet using space telescopes to collect light data when HD 20782 made its closest approach to its sun. These observations led to the detection of a change in brightness that appeared to be a signal of reflected light bouncing off the planet’s atmosphere, which could help them better understand how the planet’s atmosphere behaves at different times.
Most of the time, Kane explained, the planet is far away from its star, but it then as “a very close approach where it’s flash-heated by the star.” If a larger exoplanet moved too close to its star, the heat would likely remove the icy particles that are found in their atmospheres. In the case of HD 20782, however, “the atmosphere of the planet doesn’t have a chance to respond,” said Kane.