Crystal transformations that reduce symmetry are called "distortions". ISODISTORT (iso.byu.edu) is a powerful group-theoretical tool that can generate, parameterize, and interactively visualize virtually any crystal distortion involving atomic displacements, magnetic moments, occupational orderings, or lattice strains. Figure based on La2CoRuO6 (J. Mater. Chem. 15, 715-720, 2005).
The figure shown to the left is from a recent publication in the Astronomical Journal (Oberst, Thomas E., et al., 2017, AJ, 153, 97) that confirms the discovery of a highly irradiated, ultra-short period hot Jupiter in orbit around a distant star. The newly discovered planet has been designated as KELT–16b. The long time series run in the left hand panel that is labeled "Pratt" is from a team of students led by Dr. Denise Stephens using the BYU campus Orson Pratt Observatory. The four multi-color data sets that follow were secured a couple of days later by students under the direction of Dr. Michael Joner at the BYU West Mountain Observatory. These and the other data presented in the paper confirm the sub-stellar mass and other properties of KELT-16b.
The irreducible representations (IRs) of the parent symmetry of a system provide a symmetry-motivated parameter set for describing any periodic or aperiodic distortion. The IRs of complete crystallographic space groups and their extensions to (3+d)-dimensional superspace, including all special and non-special k-vectors, commensurate and incommensurate, have now been exhaustively tabulated for the first time. Photo (Wikipedia): Table Mountain, Capetown, South Africa.
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
21 Jul, Today
22 Jul, Saturday
24 Jul, Monday
Mark Beecher, Dennis Eggett, David Erekson, Lawrence Rees, Jennie Bingham, Jared Klundt, Russ Bailey, Clark Ripplinger, Jessica Kirchhoefer, Derek Griner, Jon Cox, and RD Boardman et al. recently published an article titled "Sunshine on my shoulders: Weather, pollution, and emotional distress" in Journal of Affective Disorders . Click on the image above to read it.
Phobos: Moon over Mars: A tiny moon with a scary name, Phobos emerges from behind the Red Planet in this timelapse sequence from the Earth-orbiting Hubble Space Telescope. Over 22 minutes the 13 separate exposures were captured near the 2016 closest approach of Mars to planet Earth....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.