News and Events

Saturn and Jupiter are getting closer. Every night that you go out and check for the next two months, these two bright planets will be even closer together on the sky. Finally, in mid-December, a Great Conjunction will occur -- when the two planets will appear only 0.1 degrees apart -- just one fifth the angular diameter of the full Moon. And this isn't just any Great Conjunction -- Saturn (left) and Jupiter (right) haven't been this close since 1623, and won't be nearly this close again until 2080. This celestial event is quite easy to see -- already the two planets are easily visible toward the southwest just after sunset -- and already they are remarkably close. Pictured, the astrophotographer and partner eyed the planetary duo above the Tre Cime di Lavaredo (Three Peaks of Lavaredo) in the Italian Alps about two weeks ago. Follow: Live coverage of today's OSIRIS-REx attempted touchdown-and-go on asteroid Bennu
Check current conditions and historical weather data at the ESC.
The BYU Department of Physics and Astronomy invites applications for two faculty positions to begin August 2021. The application deadline is October 15, 2020.
New state-of-the-art 23 inch telescope making access to the night sky a dream come true
New self-enclosed mill to enhance machining capabilities
Thanking our retireed colleagues and welcoming new ones

Selected Publications

BYU Authors: Basu R. Aryal, Dulashani R. Ranasinghe, Tyler R. Westover, Diana G. Calvopiña, Robert C. Davis, John N. Harb, and Adam T. Woolley, published in Nano Res.

DNA-based nanofabrication of inorganic nanostructures has potential application in electronics, catalysis, and plasmonics. Previous DNA metallization has generated conductive DNA-assembled nanostructures; however, the use of semiconductors and the development of well-connected nanoscale metal—semiconductor junctions on DNA nanostructures are still at an early stage. Herein, we report the first fabrication of multiple electrically connected metal—semiconductor junctions on individual DNA origami by location-specific binding of gold and tellurium nanorods. Nanorod attachment to DNA origami was via DNA hybridization for Au and by electrostatic interaction for Te. Electroless gold plating was used to create nanoscale metal—semiconductor interfaces by filling the gaps between Au and Te nanorods. Two-point electrical characterization indicated that the Au—Te—Au junctions were electrically connected, with current—voltage properties consistent with a Schottky junction. DNA-based nanofabrication of metal—semiconductor junctions opens up potential opportunities in nanoelectronics, demonstrating the power of this bottom-up approach.

BYU Authors: J. Ward Moody, published in Astrophys. J.

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ∼27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsähovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare “decline” epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ∼25–55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ≳ 33) and the size of the emission region () are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux–flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model.

BYU Authors: Wiley S. Morgan, John E. Christensen, Parker K. Hamilton, Jeremy J. Jorgensen, Branton J. Campbell, Gus L.W. Hart, and Rodney W. Forcade, published in Comput. Mater. Sci.

In the DFT community, it is common practice to use regular k-point grids (Monkhorst-Pack, MP) for Brillioun zone integration. Recently Wisesa et al. (2016) and Morgan et al. (2018) demonstrated that generalized regular (GR) grids offer an advantage over traditional MP grids. The difference is simple but effective. At the same k-point density, GR grids have greater symmetry and 60% fewer irreducible k-points. GR grids have not been widely adopted because one must search through a large number of candidate grids; in many cases, a brute force search could take hours. This work describes an algorithm that can quickly search over GR grids for those that have the most uniform distribution of points and the best symmetry reduction. The grids are 60% more efficient, on average, than MP grids and can now be generated on the fly in seconds.