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Posted By: Mona - Astronomy Astonishing exoplanets - 09/23/17 04:36 PM
A PLANET DARKER THAN FRESH ASPHALT

Exoplanets - aka extrasolar planets - are planets that orbit other stars.

Scientific American reports that a huge hot world, WASP-12b, is darker than fresh asphalt. The exoplanet, lying about 1400 light years away, is about twice Jupiter's size. Once almost every twenty-four hours it orbits its star.

WASP-12b is a hellish place. Its star's gravity has pulled it into an egg shape, and temperatures on the dayside are about 2600 C (4700 F). This temperature would easily melt most metals.

Though WASP-12b reflects virtually no light, it does emit some: The planet is so hot that it glows red like molten metal, researchers said.

Posted By: Mona - Astronomy Re: Astonishing exoplanets - 09/30/17 06:47 PM
A PLANET THAT'S HOTTER THAN A STAR

KELT-9 is a young hot blue star. It's more than twice the size and temperature of our Sun.

But more interesting than the star is its strange planet KELT-9b, the hottest gas giant yet discovered. It keeps the same side to its planet and the dayside temperature is more than 4600 C (7800 F), which is hotter than most stars. The nightside is in perpetual darkness. Although planets usually orbit their star's equator, KELT-9b goes over the poles, orbiting every two Earth days.

KELT-9b's long term prospects aren't good. The astronomers that discovered it think that it will suffer one of two fates. Its star radiates so much ultraviolet radiation that it may just evaporate the planet. Or when the star swells into a red giant, it will engulf its planet.
Posted By: Mona - Astronomy Re: Astonishing exoplanets - 10/06/17 02:40 PM
RAINING RUBIES AND SAPPHIRES?

An artist's interpretation of the exoplanet HAT-P-7b.
Quote:
It's a super-sized planet 1000 light years from Earth [with] clouds that may contain the building blocks of rubies and sapphires . . . The planet is about 40% larger than Jupiter and is baked to a searing 1900°C (3500°F), in part because it’s so close to its star – it completes an orbit every two days.

The winds transport clouds from the night side, so the cloud bank stretches some way into the day side before finally evaporating. . . . As the clouds evaporate, the planet absorbs more light and warms up, strengthening the winds.

When we say clouds, they’re definitely not clouds like on the Earth . . . The planet is so hot that minerals would be vaporised. Based on its boiling point, the clouds are likely made of corundum, the same mineral that produces sapphires and rubies on Earth.

Gemstone rain? The ultimate bling.
Posted By: Mona - Astronomy Re: Astonishing exoplanets - 10/08/17 04:31 AM
A PLANET NEARLY THREE TIMES AS OLD AS THE SOLAR SYSTEM

An artist's impression of Methuselah, an exoplanet nearly as old as the Universe. (Methuselah has a boring official name too: PSR B1620-26 b.) It's about 2.5 times as massive as Jupiter and located some 12,400 light years from us, in the constellation Scorpius.

The planet appears to be 12.7 billion years old, which is impressive in a universe that's about 13.7 billion years old. (Our Sun is about 4.5 billion years old.) If age weren't enough, Methuselah also orbits two stars - this is known as a circumbinary orbit. (It's rare, but other circumbinary planets have been discovered since then.) It orbits at z distance slightly more than the distance between Uranus and the Sun, taking about 100 years to orbit.

Both of its stars are dead. One is a pulsar, a neutron star which is the remnant of a massive star that ran out of nuclear fuel and exploded as a supernova. The other is a white dwarf, the remnant of a sunlike star that ran out of fuel and collapsed into a small dense body that is slowly cooling.
Posted By: Mona - Astronomy Re: Astonishing exoplanets - 10/10/17 05:18 AM
A PINK PLANET

GJ 504b is a gas giant that's less than sixty light years away in the constellation Virgo. Would little girls would love the Pink Planet? Yes, that's its nickname, though a member of the team that discovered it described it as "a dark cherry blossom, a dull magenta".

What really fascinates astronomers isn't the color, but what's it doing so far from its star? Here's a diagram showing how far the GJ 504b is from its star. Anything at that distance from our Sun would be out in the Kuiper Belt. It's a puzzle. Theories about gas giant formation can't explain how it got way out there.
Posted By: Mona - Astronomy Re: Astonishing exoplanets - 10/15/17 01:23 PM
Here is an infographic summarizing the different types of exoplanets - at least, the ones we know of so far!
Posted By: Mona - Astronomy Re: Astonishing exoplanets - 10/29/17 05:58 AM
THE PLANET WHERE IT SNOWS SUNSCREEN

The Kepler-13 system is 1730 light years from Earth.

The Hubble Space Telescope has found a planet orbiting one of the system's stars. The planet Kepler-13Ab is so close to its parent star that it's tidally locked. That means one side of the planet always faces the star, and the other is in permanent darkness. As a really massive planet close to its star, Kepler-13Ab is known as a hot Jupiter.

On this blistering hot planet it "snows" sunscreen. In case that sounds handy, the sunscreen (titanium oxide) precipitation only happens on the planet's permanent nighttime side, not on the sizzling hot, daytime side, which always faces its host star.

Hubble astronomers suggest that powerful winds carry the titanium oxide gas around to the colder nighttime side, where it condenses into crystalline flakes, forms clouds, and precipitates as snow. Kepler-13Ab's strong surface gravity -- six times greater than Jupiter's -- pulls the titanium oxide snow out of the upper atmosphere and traps it in the lower atmosphere.

[Keith Cowing, SpaceRef]
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