From Universe Today: “Red Dwarf Star, Planet Orbiting at Right Angles. Mayhem.”


Universe Today

20 Dec , 2017
Matt Williams

Artist’s impression of vessels floating near GJ436 its exoplanet, which orbits its star from pole to pole. Credit: University of Geneva/Denis Bajram

When we think of other planetary systems, we tend to think that they will operate by the same basic rules as our own. In the Solar System, the planets orbit close to the equatorial plane of the Sun – meaning around its equator. The Sun’s rotational axis, the direction of its poles based to its rotation, is also the same as most of the planets’ (the exception being Uranus, which rotates on its side).

But if the study of extra-solar planets has taught us anything, it is that the Universe is full of possibilities. Consider the star known as GJ436, a red dwarf located about 33 light-years from Earth. For years, astronomers have known that this star has a planet that behaves very much like a comet. But according to a recent study led by astronomers from the University of Geneva (UNIGE), this planet also has a very peculiar orbit.

The study, titled Orbital Misalignment of the Neptune-mass Exoplanet GJ 436b With the Spin of its Cool Star, recently appeared in the scientific journal Nature. The study was led by Vincent Bourrier of the Geneva University Observatory, and included members from the University of Grenoble Alpes, Tennessee State University, and the Center for Space and Habitability at the University of Bern.

Artist’s concept of the Neptune-sized planet Gliese 436b, surrounded by an envelop of hydrogen gas. Credit: NASA/ESA/STScI/G. Bacon

GJ436 has already been the source of much scientific interest, thanks in part to the discovery that its only confirmed exoplanet has a gaseous envelop similar a comet. This exoplanet, known as GJ436b, was first observed in 2004 using radial velocity measurements taken by the Keck Observatory.

Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level, showing also NASA’s IRTF and NAOJ Subaru

In 2007, GJ436b became the first Neptune-sized planet known to be orbiting very closely to its star (aka. a “Hot Neptune”).

See the full article here .

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