Washington : A team of astronomers has seen flashes of light from a mystery world that behaves like a comet.
The team, led by San Francisco State University astronomer Stephen Kane, spotted an extra-solar planet about 117 light-years from Earth that boasts the most eccentric orbit yet seen.
Kane and his colleagues were able to detect a signal of reflected light from the planet known as HD 20782 a “flash” of starlight bouncing off the eccentric planet’s atmosphere as it made its closest orbital approach to its star.
In this case, “eccentric” doesn’t refer to a state of mind, but instead describes how elliptical a planet’s orbit is around its star. While the planets in our solar system have nearly circular orbits, astronomers have discovered several extrasolar planets with highly elliptical or eccentric orbits.
HD 20782 has the most eccentric orbit known, measured at an eccentricity of .96. This means that the planet moves in a nearly flattened ellipse, traveling a long path far from its star and then making a fast and furious slingshot around the star at its closest approach.
HD 20782 offers “a particularly lucrative observing opportunity” for studying the planetary atmosphere of an eccentric-orbit planet-a type not seen in our own solar system, the scientists say in the journal article. By studying the reflected light from HD 20782, astronomers may learn more about the structure and composition of a planetary atmosphere that can withstand a brief but blistering exposure to its star.
At the furthest point in its orbit, the planet is separated from its star by 2.5 times the distance between the sun and Earth. At its closest approach, it ventures as close as .06 of that same Earth-sun distance, much closer than Mercury orbits the sun, said Kane, an assistant professor of physics and astronomy. “It’s around the mass of Jupiter, but it’s swinging around its star like it’s a comet.”
The study appears in The Astrophysical Journal. (ANI)