astro pictures

"Upside-down planet" reveals new method for studying binary star systems
Working with UW astronomer Eric Agol, doctoral student Ethan Kruse has confirmed the first “self-lensing” binary star system — one in which the mass of the closer star can be measured by how powerfully it magnifies light from its more distant companion star. Though our sun stands alone, about 40 percent of similar stars are in binary (two-star) or multi-star systems, orbiting their companions in a gravitational dance.



‘Dimer molecules’ aid study of exoplanet pressure, hunt for life
Astronomers at the University of Washington have developed a new method of gauging the atmospheric pressure of exoplanets, or worlds beyond the solar system, by looking for a certain type of molecule. And 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. The method, devised by Amit Misra, a UW astronomy doctoral student, and co-authors, 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.



UW astronomer Eric Agol’s seven-planet system part of major NASA discovery
University of Washington astronomer Eric Agol played a key role in the windfall of 715 new exoplanets announced by NASA Feb. 26. Agol was on a team that found seven of those worlds, all in orbit around the same star, Kepler-90. It’s the first planetary system with seven planets seen to transit, or cross in front of their host star.



Astronomers solve temperature mystery of planetary atmospheres
University of Washington (UW) researchers Tyler Robinson and David Catling have found an atmospheric peculiarity Earth shares with Jupiter, Saturn, Uranus, and Neptune is likely common to billions of planets, and knowing that may help in the search of potentially habitable worlds. Earth and other solar system worlds have a tropopause, or level where the atmosphere stops cooling and begins heating up, at or near 0.1 bars. Using an analytic model, Robinson and Catling show that at high altitudes atmospheres become transparent to thermal radiation due to the low pressure. Above the level where the pressure is about 0.1 bar, the absorption of visible, or ultraviolet, light causes the atmospheres of the giant planets — and Earth and Titan — to grow warmer as altitude increases.



'Runaway greenhouse' may be easier to trigger than previously thought
According to a study published July 28 in Nature Geoscience, astronomers at the University of Washington and the University of Victoria say that it may be easier than previously thought for a planet to overheat during the so-called "runaway greenhouse" stage. This discovery does not bode well for some planets that are currently labeled as 'possibly habitable' as their suitability for such consideration may be revoked.




 
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