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Project Progress

We have worked to improve the velocity precision of the HET spectrograph to the level where it can do Kepler followup and detect low mass planets orbiting the nearest stars.

The Exoplanet Orbit Database remains a vital resource to the community, providing the best list of good exoplanet orbital and host-star parameters. We continue to maintain and expand this website. We recently published a paper describing these updates as PASP,126,827.

We have identified the dominant sources of error in the iodine technique at HET and Keck, and are working to mitigate them. New iodine spectra: Ming Zhao and Sharon Wang have obtained echelle spectra at high resolution (R~450,000) of in-use iodine cells, including the one at HET. These spectra, made at multiple temperatures will finally allow us to determine the sources of variation in iodine spectra taken at Fourier Transform Spectrographs, and remove modeling the iodine cells from the Doppler error budget at HET and Keck.

We have discovered that the dominant source of noise at Keck Observatory is the presence of weak telluric features in the optical spectra. These features are usually masked out of all Doppler analysis, but apparently the weakest lines remain at a level sufficient to be the “tallest tent pole” in the error budget. Sharon Wang is implementing new code to remove them completely and improve the precision there, improving our sensitivity to low-mass planets.

We have published a hypothesis regarding the origin of the Lunar Farside Highlands, with implications for the giant impact hypothesis and lunar formation.

HPF is currently being designed and built including progress on very high levels of temperature and pressure control.

Work by Mahadevan and Robertson has shown that stellar activity can masquerade as planet RV signatures (GLiese581d).

We have published detailed models of rates of ejection, transport and impact for impact ejecta from the inner Solar System to the outer Solar System.

Rates and timescales are consistent with ejecta transporting biological materials potentially contaminating the larger moons of the outer planets.

Ford’s group is analyzing astronomical observations to characterize the architectures of individual planetary systems and to develop a statistical understanding of the distribution of planet and planetary systems. Graduate student Benjamin Nelson is characterizing the architecture of individual planetary systems with Doppler observations, and performing exploratory statistical analyses of Doppler observations as part of a larger effort to improve the precission of Doppler observations. Graduate student Shabram is focusing on the orbital eccentricity distribution of Kepler’s planet candidates. Graduate student Robert Morehead is investigating Kepler’s multiple transiting planet candidate systems to compute false alarm probabilities, confirm planets and characterize the distribution of mutual inclinations in planetary systems with multiple planets. Research associate Daniel Jontof-Hutter is characterizing the masses and orbits of planetary systems with transit timing variations detected by Kepler.