astro pictures

‘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.

A warmer planetary haven around cool stars, as ice warms rather than cools
In a bit of cosmic irony, planets orbiting cooler stars may be more likely to remain ice-free than planets around hotter stars. This is due to the interaction of a star's light with ice and snow on the planet's surface. It seems logical that the warmth of terrestrial or rocky planets should depend on the amount of light they get from their stars, all other things being equal. But new climate model research led by Aomawa Shields, a doctoral student in the University of Washington astronomy department, has added a surprising new twist to the story: planets orbiting cool stars actually may be much warmer and less icy than their counterparts orbiting much hotter stars, even though they receive the same amount of light.

Super-Earths detected in nearby star system
A team of astronomers, including Rory Barns at the University of Washington, have discovered a nearby star system containing three to five "super-Earths" in its habitable zone. "Super-Earths" are planets up to ten times bigger than Earth and, according to the researchers, this is the first time so many have been detected in one system. "These planets are good candidates to have a solid surface and maybe an atmosphere like the Earth's, not something like Jupiter," said Barnes.

Kepler Stars and Planets are Bigger than Previously Thought
In a new study using the NOAO Kitt Peak National Observatory Mayall 4-meter telescope, observations of a large sample of stars with candidate planets identified by the NASA Kepler Mission have revealed that many of the stars, and hence their planets, are actually somewhat larger than originally thought. In addition, the researchers confirm that planets larger than Neptune are more likely to be found orbiting stars that contain more heavy elements (such as iron) than the Sun. Small planets, however, have been discovered around stars both rich and poor in metals. Over three years ago, Steve B. Howell (NASA Ames Research Center) put together a team to investigate and characterize the stars that the NASA Kepler Mission found to host planets. The team members are Mark Everett and David Silva (both at NOAO) and Paula Szkody (University of Washington).

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