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Thursday, 4 December 2008

Exo-planets in October, 2008

In today's edition:

  1. Mysterious changes seen on distant dwarf planet
  2. Exoplanets finally come into view
  3. Not giving up the ghost: Mars Spirit rover lives
Ok, I kind of broke in two my posts, but this way it's more systematic. And the optical detection of exo-solar planets is significant enough to have its own post.

Mysterious changes seen on distant dwarf planet

The surface of the largest known 'plutoid' appears to have changed in recent years, according to new measurements of how elements are layered on its icy surface. But astronomers cannot explain the cause of the apparent change.

Eris is the largest known object beyond the orbit of Neptune, weighing nearly a third more than Pluto. It travels on an elongated path around the Sun that takes about 560 years to complete.

Astronomers think the distant world is covered by a layer of frozen methane and small amounts of nitrogen ice which may vaporise and condense depending of the distance to the Sun.

Eris is now near its farthest point from the Sun, so it is expected to be cold and inactive. But a new study suggests the dwarf planet's surface may have changed in the last few years.

Tegler and colleagues probed Eris's supposedly inactive surface by measuring how methane ice absorbed the Sun's light and concluded that the concentration of nitrogen seems to increase with depth.

That result, based on observations of five wavelength bands in 2007, contradicts observations made in 2005 with the 4.2-m William Herschel Telescope in Spain. The 2005 observations, which measured two bands of light, suggested that nitrogen is more abundant closer to the surface.

The researchers consider both sets of observations to be valid valid, but they still don't know what caused the difference. Possibilities include weather change, volcano eruptions or that this simply is the rotated part of the little planet.

NASA's New Horizons mission, which is set to fly past Pluto in 2015, could help determine whether the erstwhile planet ever boasted similar eruptions. source

My comment: If Eris has volcanic activity, that would be amazing kick in the ass for astronomers. Ok, I really think them little arrogant and I'm still mad about Pluto, so don't judge me too harsh. In any case, it's very interesting, since something so small and distant can keep its internal energy and stay hot. On Saturn and Jupiter's moons that could be explained by tidal forces, but on those distant worlds it's definitely strange.

Exoplanets finally come into view

Three exoplanets (NRC-HIA/ IDPS/ Keck)
Three exoplanets orbiting the same star have been imaged directly

The first pictures of planets outside our Solar System have been taken, two groups report in the journal Science.

Visible and infrared images have been snapped of a planet orbiting a star 25 light-years away.

The planet is believed to be the coolest, lowest-mass object ever seen outside our own solar neighbourhood.

In a separate study, an exoplanetary system, comprising three planets, has been directly imaged, circling a star in the constellation Pegasus.

But advances in optics and image processing have allowed astronomers to effectively subtract the bright light from stars, leaving behind light from the planets. That light can either come in the infrared, caused by the planets' heat, or be reflected starlight.

Paul Kalas of the University of California, Berkeley, led an international group that used the Hubble Space Telescope to image the region around a star called Fomalhaut in the constellation Piscis Austrinus. The star has a massive ring of dust surrounding it that appears to have a cleanly groomed inner edge.

The team estimates that the planet, designated Fomalhaut b, is some 18 billion kilometres (11 billion miles) away from its star, about as massive as Jupiter and completes an orbit in about 870 years. It may also have a ring around it.

Christian Marois of the Herzberg Institute for Astrophysics, Canada, and his team used the Keck and Gemini telescopes in Hawaii to look near a star called HR 8799, which is just visible to the naked eye.

The team studied light in the infrared part of the spectrum, hoping to spot planets that were still hot from their formation.

What they found in 2004, and confirmed again this year, are three planets circling the star.

According to a theoretical model that accounts for the light coming from the planets, they range in size from five to 13 times the mass of Jupiter and are probably only about 60 million years old.

The trio have similarities with our own Solar System. Their orbits are comparable in size to those of the outer planets, and the smaller planets are those closest to the Sun - again suggesting a system that formed through accretion.

The study of the light directly from the planets will yield information about their atmospheres and surfaces that is impossible to collect from planets discovered indirectly.

Further, the current results will also support theories of how planets form from the grand discs of dust and material around stars, and lead to better estimates of how many Earth-like planets are likely to exist. source

My comment: That's certainly nice! And what's even nicest-it's in the Pegasus constellation! Stargate Atlantis everyone! Ok, fun aside, it's amazing how things we previously thought absolutely impossible are now coming to reality. And just imagine if we can see this with our telescopes- powerful, but not quite optimized for planets- what wecould see with real tools made for planet hunting.

Not giving up the ghost: Mars Spirit rover lives

WASHINGTON – Despite a nasty Martian dust storm, Spirit lives.

NASA had not heard from the 5-year-old Martian rover for four days. Just when engineers feared having to give up the ghost, the aptly named robot radioed back to Earth on Thursday that it survived.

Engineers were afraid that a dust storm had drained Spirit's solar batteries, triggering it to shut down. Spirit's batteries are low, but working.

Spirit and its twin, Opportunity, are living long past their planned three months on Mars. source

My comment: Hehe, ain't that great! It simply fitted the post theme. How much joy the little machine can bring-but hey, just imagine how much money and work it was invested in it.

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