Searching for Oxygen Molecules on Alien Planets --Astronomers Develop New ET Sea
- FYIRead more about dimer at http://en.wikipedia.org/wiki/Dimer_(chemistry)
Sent: 3/5/2014 6:45:21 P.M. Eastern Standard Time
Subj: The Daily Galaxy: News from Planet Earth & Beyond
Posted: 05 Mar 2014 07:43 AM PST
A team of astronomers have realized that oxygen dimer molecules are often more detectable in an alien planet atmosphere than other markers of oxygen. That’s important from a biological standpoint. “It’s tied to photosynthesis, and we have pretty good evidence that it’s hard to get a lot of oxygen in an atmosphere unless you have algae or plants that are producing it at a regular rate," says Amit Misra, withthe University of Washington astronomy department. "So if we find a good target planet, and you could detect these dimer molecules — which might be possible within the next 10 to 15 years — that would not only tell you something about pressure, but actually tell you that there’s life on that planet.”The University of Washington team has developed a new method of gauging the atmospheric pressure of exoplanets, or worlds beyond the solar system, by looking for the oxygen molecule. If there is life out in space, scientists may one day use this same technique to detect its biosignature — the telltale chemical signs of its presence — in the atmosphere of an alien world. Understanding atmospheric pressure is key to knowing if conditions at the surface of a terrestrial, or rocky, exoplanet might allow liquid water, thus giving life a chance.
The method, devised by Misra, a UW astronomy doctoral student, and Victoria Meadows, professor of astronomy, involves computer simulations of the chemistry of Earth’s own atmosphere that isolate what are called “dimer molecules” — pairs of molecules that tend to form at high pressures and densities in a planet’s atmosphere. There are many types of dimer molecules but this research focused only on those of oxygen.
The researchers ran simulations testing the spectrum of light in various wavelengths. Dimer molecules absorb light in a distinctive pattern, and the rate at which they form is sensitive to the pressure, or density, in the planet’s atmosphere.
“So the idea is that if we were able to do this for another planet, we could look for this characteristic pattern of absorption from dimer molecules to identify them,” Misra said. The presence of such molecules, he said, likely means the planet has at least one-quarter to one-third the pressure of Earth’s atmosphere.
Powerful telescopes soon to come online, such as the James Webb Space Telescope, scheduled for launch in 2018, may enable astronomers to use this method on distant exoplanets. With such enhanced tools, Misra said, astronomers might detect dimer molecules in actual exoplanet atmospheres, leading to a clear understanding of the planet’s atmosphere
Misra’s UW co-author include Meadows and Mark Claire of Scotland’s University of St. Andrews and Dave Crisp of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
The research was performed through the UW-based Virtual Planetary Laboratory and funded by NASA.
The Daily Galaxy via University of Washington
Image credit: US Coast GuardCreUdit: US Coast Guard
Posted: 05 Mar 2014 07:11 AM PST
The spiral plows through the seething intra-cluster gas so rapidly – at nearly 4.5 million miles per hour — that much of its own gas is caught and torn away. Astronomers call this "ram pressure stripping." The galaxy’s stars remain intact due to the binding force of their gravity. Tattered threads of gas, the blue jellyfish-tendrils trailing ESO 137-001 in the image, illustrate the process. Ram pressure has strung this gas away from its home in the spiral galaxy and out over intergalactic space. Once there, these strips of gas have erupted with young, massive stars, which are pumping out light in vivid blues and ultraviolet.
The spiral galaxy ESO 137-001 looks like a dandelion caught in a breeze in this new Hubble Space Telescope image. The galaxy is zooming toward the upper right of this image, in between other galaxies in the Norma cluster located over 200 million light-years away. The road is harsh: intergalactic gas in the Norma cluster is sparse, but so hot at 180 million degrees Fahrenheit that it glows in X-rays.
The brown, smoky region near the center of the spiral is being pushed in a similar manner, although in this case it is small dust particles, and not gas, that are being dragged backwards by the intra-cluster medium.
From a star-forming perspective, ESO 137-001 really is spreading its seeds into space like a dandelion in the wind. The stripped gas is now forming stars. However, the galaxy, drained of its own star-forming fuel, will have trouble making stars in the future. Through studying this runaway spiral, and other galaxies like it, astronomers hope to gain a better understanding of how galaxies form stars and evolve over time.
The image, obtained through Hubble’s Wide Field Camera 3, is also decorated with hundreds of stars from within our own Milky Way galaxy. Though not connected in the slightest to ESO 137-001, these stars and the two reddish elliptical galaxies contribute to a vibrant celestial vista.
The Daily Galaxy via Ray Villard, Space Science Telescope Institute, Baltimore, Md.
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