Exoplanets

Several aspects of extrasolar planets are of interest to our group, but we principally do research on transiting extrasolar planets, and astrometric follow-up of planet candidates.

---

Transiting planets

Transiting extrasolar planets are planets around other stars whose orbit happens to be aligned just right such that we observe them to pass in front of their host star once each orbit. This results in a very small dimming of the host star's brightness, which along with other measurements can reveal the planet's mass, radius, density, temperature, and even atmospheric composition. As well, by observing multiple transits over time, one can also deduce the presence of additional planets or moons in the system.

At NMSU, we use ARC's 3.5-meter and NMSU's 1-meter telescopes at Apache Point Observatory, and other research-class telescopes, to obtain observations of exoplanet transits. As well, our group has recently built a multi-channel photometer that will obtain high-cadence observations of exoplanet transits simultaneously at multiple wavelengths. Through these observations, we refine physical and orbital exoplanet parameters, probe their atmospheres, and search for new planets.

Some collaborators on this work with our group include Mercedes López Morales (Carnegie Institution of Washington), Mark Marley (NASA Ames), Andy Becker (U. Washington).

---

Astrometric follow-up

Many extrasolar planets are found via the radial-velocity technique, which only reveals the planet's mass as a function of inclination, which is unknown. If the inclination is low, the object may not be a planet after all, but a brown dwarf, an object with a mass between that of a planet and a star. We use the fine guidance sensor the Hubble Space Telescope to search for an astrometric signature, the motion of the star induced by the orbiting planet, which reveals the inclination of the system and thus the true planet mass.