Monday, 2 July 2012

Astrophysics stuff from the week 25/6 - 1/7/12

How is the sun's corona so much hotter than its surface layer?
Mathematicians at the University of Sheffield have identified that magnetic super tornadoes, more than 1000 mph wide, and spinning at 6000 mph, draw energy out into the corona, amplifying its temperature to millions of kelvin.
This magnetic tornado phenomenon could be used on Earth to produce energy in large quantities, but with negligible danger of pollution.

If you'd asked me to draw a map of all the space agencies around the world, i would *not* have drawn that many on it!
"For any space nerd, that would be the ultimate global trek, to visit every space agency in the world. With all the NASA and Russian centers and all the various countries in ESA, your trip would include 198 locations around our planet!"

[video] An international team has used ESO's Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b, in the infra red range.
Tau Boötis b is a Jupiter-sized planet, orbiting a star 50 light years away and visible to the naked eye, but does not pass between its star and Earth.
This is why it was one of the first to be identified using the radial velocity method, whereby its mass was observed to cause its host star to wobble, during its orbit.
Because Tau Boötis b does not pass between its star and us, its atmospheric composition could not be inferred from the way it attenuated solar light, on its journey here.
"But now, after 15 years of attempting to study the faint glow that is emitted from hot Jupiter exoplanets, astronomers have finally succeeded in reliably probing the structure of the atmosphere of Tau Bootis b and deducing its mass accurately for the first time."
"By tracing the changes in the planet's motion as it orbits its star, the team has determined reliably for the first time that Tau Bootis b orbits its host star at an angle of 44 degrees and has a mass six times that of the planet Jupiter in our own Solar System."
Spectroscopy for the win!

Another fascinating exoplanet, this week: HD 189733b (I know - they have catchy names!)
HD 189733b was seen by Hubble to flare up, developing a tail, much like a comet, which must have involved a massive amount of energy, because the evaporating gas was emitted at thousands of tonnes per second.
"Despite the extreme temperature of the planet, the atmosphere is not hot enough to evaporate at the rate seen in 2011. Instead the evaporation is thought to be driven by the intense X-ray and extreme-ultraviolet radiation from the parent star, HD 189733A, which is about 20 times more powerful than that of our own Sun. Taking into account also that HD 189733b is a giant planet very close to its star, then it must suffer an X-ray dose 3 million times higher than the Earth."
The team concluded that the planet was struck by a solar flare, which ripped some of the planet's atmosphere away, and propelled it into space. That's the cost of orbiting so close to your parent star! (Just one thirtieth of the distance between Earth and our Sun)

And yet more exoplanets: 'Exoplanetary bedfellows make odd couple'
"When Josh Carter of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and his team looked at data from the Kepler space telescope, they found a rocky planet with a radius 1.5 times greater than Earth's, orbiting within a cosmic whisker of a gassy planet with a radius 2.5 times larger still. The pair are 20 times closer than Earth and Venus"