Physics Colloquia

From Extreme Binary Stars to Self-Driving Cars
Dr. Tony Rodriguez
Data Scientist, Waymo LLC (formerly Harvard CfA)

Compact objects -- white dwarfs (WDs), neutron stars, and black holes -- are laboratories for studying extreme physics under conditions unable to be replicated on Earth. When located in binaries, it becomes possible to measure properties of compact objects such as magnetic field strength, temperature, and the effects of mass transfer from a companion. In this talk, I will describe recent advancements in our understanding of WD magnetism.

Solving Atomic Structures of Molecules and Nanoclusters Using Superfluid Helium Droplet Cooling and Laser Alignment
Wei Kong
Department Head & Professor, Department of Chemistry - Oregon State University

We are building a prototype experimental apparatus to determine the atomic structures of molecules and nanoclusters using electron diffraction. We use superfluid helium droplets for cooling, thereby achieving effective field-induced orientation and alignment of the sample species. Electron diffraction patterns from the chosen orientation can then be accumulated until a satisfactory signal-to-noise ratio can be obtained.

How Dark is Space?
Tod R. Lauer
Astronomer, NOIRLab

We used NASA’s New Horizons spacecraft to measure the cosmic optical background (COB) intensity integrated over 0.4 ≲ λ ≲ 0.9 μm. The survey comprises 16 high Galactic-latitude fields. Images were obtained with the LORRI camera when New Horizons was 57 AU distant from the Sun. As such, the sky intensity measurements were unaffected by zodiacal light, which strongly interferes with COB measurements attempted from the inner solar system. T he survey yields a highly significant detection (6.8σ) of the COB at 11.16 ± 1.65 (1.47 sys, 0.75 ran) nW m−2 sr−1 at the LORRI pivot wavelength of 0.608 μm. The estimated integrated intensity from background galaxies, 8.17 ± 1.18 nW m−2 sr−1, can account for the great majority of this signal. The rest of the COB signal is formally classified as anomalous intensity but is not significantly different from zero. The simplest interpretation is that the COB is completely due to galaxies.