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Astrophysicist proposes new definition of a planet

22 January 2018 Astronomy Now

Pluto hogs the spotlight in the continuing scientific debate over what is and what is not a planet, but a less conspicuous argument rages on about the planetary status of massive objects outside our solar system. The dispute is not just about semantics, as it is closely related to how giant planets like Jupiter form.

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Scientists improve brown dwarf weather forecasts

17 August 2017 Astronomy Now

Dim objects called brown dwarfs, less massive than the Sun but more massive than Jupiter, have powerful winds and clouds — specifically, hot patchy clouds made of iron droplets and silicate dust. Scientists recently realised these giant clouds can move and thicken or thin surprisingly rapidly, in less than an Earth day, but did not understand why.

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Brown dwarfs hiding in plain sight in our solar neighbourhood

7 September 2016 Astronomy Now

Brown dwarfs are sometimes called failed stars as they are too small to sustain the hydrogen fusion process that powers stars. Their temperatures can range from nearly as hot as a star to as cool as a planet and their masses also range between star-like and giant-planet-like. A near-infrared survey has discovered several ultracool brown dwarfs in the Sun’s vicinity.

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Astronomers find giant planet around very young star CI Tauri

27 May 2016 Astronomy Now

Contradicting the long-standing idea that large Jupiter-mass planets take a minimum of 10 million years to form, astronomers have just announced the discovery of a giant planet in close orbit around a 2 million-year-old star that still retains a disc of circumstellar gas and dust. CI Tau b is at least eight times larger than Jupiter and 450 light-years from Earth.

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Where are the missing brown dwarfs?

9 April 2016 Astronomy Now

Brown dwarfs are objects that are too large to be called planets, yet too small to shine by nuclear fusion. Two German researchers have taken a careful look at the distribution of nearby examples of these “failed stars” and to their surprise discovered a significant asymmetry in their spatial arrangement.

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Solar storms ignite X-ray aurorae on Jupiter

22 March 2016 Astronomy Now

Solar storms are triggering X-ray aurorae on Jupiter that are about eight times brighter than normal over a large area of the planet and hundreds of times more energetic than Earth’s “northern lights,” according to a new study using data from NASA’s Chandra X-ray Observatory when a giant solar storm arrived at the planet.