ANN ARBOR — A comet-bound spacecraft that’s been in sleep mode for more than two years is scheduled to wake up on the morning of Jan. 20—beginning the home stretch of its decade-long journey to a mile-wide ball of rock, dust and ice.
If all goes as planned, Rosetta—a European Space Agency-led mission that involves University of Michigan engineers and scientists—will be the first craft to actually land on a comet as well as track it for an extended period of time. (more…)
Chondrules may have formed from high-pressure collisions in early solar system
At issue is how numerous small, glassy spherules had become embedded within specimens of the largest class of meteorites—the chondrites. British mineralogist Henry Sorby first described these spherules, called chondrules, in 1877. Sorby suggested that they might be “droplets of fiery rain” which somehow condensed out of the cloud of gas and dust that formed the solar system 4.5 billion years ago. (more…)
While astronomers now know that exoplanets are exceedingly common in the galaxy, the mechanics by which they are formed aren’t well understood. Planetary childhood remains a mystery.
Young stars start out with a massive disk of gas and dust that over time, astronomers think, either diffuses away or coalesces into planets and asteroids.
“The speculation is that as planets form they clear out a region of gas and dust around them, forming a telltale ‘gap’ in the disk”, said Stefan Kraus, from Physics and Astronomy at the University of Exeter. (more…)
Berkeley Lab’s Chemical Dynamics Beamline points to why isotope ratios in interplanetary dust and meteorites differ from Earth’s
By studying the origins of different isotope ratios among the elements that make up today’s smorgasbord of planets, moons, comets, asteroids, and interplanetary ice and dust, Mark Thiemens and his colleagues hope to learn how our solar system evolved. Thiemens, Dean of the Division of Physical Sciences at the University of California, San Diego, has worked on this problem for over three decades.
In recent years his team has found the Chemical Dynamics Beamline of the Advanced Light Source (ALS) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) to be an invaluable tool for examining how photochemistry determines the basic ingredients in the solar system recipe. (more…)
Look up at the night sky and you’ll see stars, sure. But the sky is also filled with planets — billions and billions of them at least.
That’s the conclusion of a new study by astronomers at the California Institute of Technology in Pasadena, which provides yet more evidence that planetary systems are the cosmic norm. The team made their estimate while analyzing planets orbiting a star called Kepler-32 — planets that are representative, they say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding how most of these worlds form.(more…)
Astronomers find planets in strange places and wonder if they might support life. One such place would be in orbit around a white or brown dwarf. While neither is a star like the sun, both glow and so could be orbited by planets with the right ingredients for life.
No terrestrial, or Earth-like planets have yet been confirmed orbiting white or brown dwarfs, but there is no reason to assume they don’t exist. However, new research by Rory Barnes of the University of Washington and René Heller of Germany’s Leibniz Institute for Astrophysics Potsdam hints that planets orbiting white or brown dwarfs will prove poor candidates for life. (more…)
A University of Exeter astrophysicist has shown what sunsets look like on planets outside our solar system.
He has worked out the colour of sunsets on two planets: HD 209458 b and HD 189733 b, known as ‘extrasolar planets’ because they are outside our solar system.
Extrasolar planets orbit stars, in a similar way to the Earth orbiting the Sun. Professor Frédéric Pont of the University of Exeter has used the extrasolar planets’ ‘transmission spectrum’, taken by the Hubble Space Telescope, to work out the colour of the ‘sunsets’ created by these stars.
Writing on the website ExoClimes.com, where he has posted the two sunset images he has produced, Professor Pont said: “Unlike its sister planet HD ’189, the planet HD ’209 (‘Osiris’) has a sunset that looks truly alien. The star is white outside the atmosphere, since its temperature is close to that of the Sun. It then acquires a bluish tinge as it sinks deeper, because the absorption by the broad wings of the neutral sodium lines (the spectral lines responsible for the gloomy orange of sodium street lighting) remove the red and orange from the star light. (more…)
*Brown University physicists have set the strongest limit for the mass of dark matter, the mysterious particles believed to make up nearly a quarter of the universe. The researchers report in Physical Review Letters that dark matter must have a mass greater than 40 giga-electron volts. The distinction is important because it casts doubt on recent results from underground experiments that have reported detecting dark matter.*
PROVIDENCE, R.I. [Brown University] — If dark matter exists in the universe, scientists now have set the strongest limit to date on its mass.
In a paper to be published on Dec. 1 in Physical Review Letters (available in pdf), Brown University assistant professor Savvas Koushiappas and graduate student Alex Geringer-Sameth report that dark matter must have a mass greater than 40 giga-electron volts in dark-matter collisions involving heavy quarks. (The masses of elementary particles are regularly expressed in term of electron volts.) Using publicly available data collected from an instrument on NASA’s Fermi Gamma-ray Space Telescope and a novel statistical approach, the Brown pair constrained the mass of dark matter particles by calculating the rate at which the particles are thought to cancel each other out in galaxies that orbit the Milky Way galaxy. (more…)
