All posts for the month March, 2014

Good talk today from Karen Collins, a graduate student in U of Louisville’s Physics program.

Artist's illustration of KELT-6b, a Saturn-like alien planet announced in June 2013. From

Artist’s illustration of KELT-6b, a Saturn-like alien planet announced in June 2013. From

She spoke about her work in ground-based observations of exoplanet transits, which are impressively simple but amazingly powerful for revealing new planets and telling us about already known planets.

Collins helped discover and confirm the Saturn-sized planet KELT-6 b (pictured at right), in a roughly 8 day orbit around a metal-poor F-type star.

This is a particularly interesting discovery because gas giant planets seem to prefer forming around metal-RICH stars, where there was more material to form planets. But KELT-6 b seems to buck that trend, and this result may point to something unusual about the planet’s formation and history.

Observing stellar parallax. From

Observing stellar parallax. From

Dr. Jennifer Bartlett of the US Naval Observatory visited today to talk about her work measuring parallaxes for the stars closest to us in space.

Dr. Bartlett spoke about her collaboration’s, RECONS, discovery of several low-mass binary star systems. Since the least massive stars are also the dimmest, these systems are some of the most interesting but difficult to study.

However, these stars can also be the easiest to found extrasolar planets around since the perturbations astronomers look for to find planets are enhanced for these stars, due to their low masses and sizes. But we can only really study these systems if they are close to us.

So, for several reasons, measuring the parallaxes to infer the distances to the nearest stars in the galaxy is an exciting topic.

Great talk from Ronni Grapenthin of UC Berkeley’s Seismology Lab. Dr. Grapenthin discussed how he uses high-precision and high data-rate GPS measurements to link the motions of the Earth’s crust to geophysical processes, including earthquakes and volcanic eruptions.

One of the neatest things he showed was a video of GPS displacements during the huge Tōhoku earthquake in Japan three years ago (above). The left panel shows lateral displacement (the largest arrows reflect only a few meters of displacement, not hundreds of kilometers, as it may seem), while the right panel shows vertical displacement. The waves associated with the earthquake and an aftershock are shown pretty dramatically, as they propagate through the Earth’s surface away from the earthquake source.

In the near-term, Grapenthin is helping to develop an early warning system for earthquakes in California using these kind of GPS data, which could help save many lives.