Seven students, one postdoc, and four faculty attended the 174th Meeting of the ASA in New Orleans, LA from Dec. 4-8, 2017, including chairing 4 sessions and presenting 12 talks.
Experimentally and computationally, the structure of Pt–Cu at 1:3 stoichiometry has a convoluted history. The L1_3 structure has been predicted to occur in binary alloy systems, but has not been linked to experimental observations. Using a combination of electron diffraction, synchrotron X-ray powder diffraction, and Monte Carlo simulations, we found that this phase is present in the Cu–Pt system at 1:3 stoichiometry. We also find that the 4-atom, fcc superstructure L13 is equivalent to the large 32-atom orthorhombic superstructure reported in older literature, resolving much of the confusion surrounding this composition. Monte Carlo simulations confirm the formation of a large cubic superstructure at high temperatures, and its eventual transformation to the L1_3 structure at lower temperature, but also provide evidence of other transitional orderings.
Wave-like modulations with non-lattice periodicities accompany a variety of important physical phenomena (e.g. magnetism and superconductivity). Though such a material is not properly crystalline in three dimensions, it does have a regular crystal lattice in a higher dimensional superspace. The superspace symmetry groups in (3+1), (3+2) and (3+3) dimensions have now been exhaustively tabulated, which will make it easier to solve modulated structure and understand their properties.
This image was secured just after the end of evening twilight on a clear April night from the West Mountain Observatory. The view is looking west past the domes housing the two smaller research telescopes at the observatory. The thin crescent Moon is also illuminated by reflected light from the Earth that is known as earthshine. Higher in the sky, the bright 'star' is actually the planet Venus. In between the two, the 'V' shaped group of stars in the constellation of Taurus is in reality the nearby open cluster known as the Hyades. Photo credit: Dr. Michael D. Joner
If you missed your chance to see the transit of Mercury on May 9, 2016, you only need to wait a few years to get another chance. While Venus transits are rare and occur about twice in a century, Mercury will transit the Sun 14 times in this century. The next such event will occur on November 11, 2019. Mercury is the tiny black dot seen just below the center of the picture. The larger sunspot group seen just above the center of the picture was designated AR 2542. This picture was taken in Provo by Professor Michael Joner.
19 Mar, Today
20 Mar, Tuesday
21 Mar, Wednesday
Mary Dumont, Clement Gaillard, Kyle Matt, Denise Stephens, and Mike Joner et al. recently published an article titled "A giant planet undergoing extreme-ultraviolet irradiation by its hot massive-star host" in Nature. Click on the image above to read it.
The Nebra Sky Disk : It is considered the oldest known illustration of the night sky. But what, exactly, does it depict, and why was it made? The Nebra sky disk was found with a metal detector in 1999 by treasure hunters near Nebra, Germany, in the midst of several bronze-age weapons....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.