We present the results of two 2.3 μm near-infrared (NIR) radial velocity (RV) surveys to detect exoplanets around 36 nearby and young M dwarfs. We use the CSHELL spectrograph (R ~ 46,000) at the NASA InfraRed Telescope Facility (IRTF), combined with an isotopic methane absorption gas cell for common optical path relative wavelength calibration. We have developed a sophisticated RV forward modeling code that accounts for fringing and other instrumental artifacts present in the spectra. With a spectral grasp of only 5 nm, we are able to reach long-term radial velocity dispersions of ~20–30 m s−1 on our survey targets.

We present preliminary astrometric results aimed at understanding the lifetime of circumstellar disks and potential for planet formation. We have obtained parallaxes to stars in the TW Hydrae, Upper Scorpius, and Chamaeleon I stellar associations. These enable new estimates for the ages of the stars. We are also performing the Carnegie Astrometric Planet Search of nearby low mass stars for gas giant planets on wide orbits. We have our first candidate around a mature brown dwarf.

M dwarf stars are attractive targets in the search for habitable worlds as a result of their relative abundance and proximity, making them likely targets for future direct detection efforts. Hot super-Earths as well as gas giants have already been detected around a number of early M dwarfs, and the former appear to be the high-mass end of the population of rocky, terrestrial exoplanets. The Carnegie Astrometric Planet Search (CAPS) program has been underway since March 2007, searching ~ 100 nearby late M, L, and T dwarfs for gas giant planets on orbits wide enough for habitable worlds to orbit interior to them. The CAPSCam-N camera on the 2.5-m du Pont telescope at the Las Campanas Observatory has demonstrated the ability to detect planets as low in mass as Saturn orbiting at several AU around late M dwarfs within 15 pc. Over the next decade, the CAPS program will provide new constraints on the planetary census around late M dwarf stars, and hence on the suitability of these nearby planetary systems for supporting life.

According to current plans, the SIM/NASA mission will be launched just after the end of operations for the Gaia/ESA mission. This is a new situation which enables long term astrometric projects that could not be achieved by either mission alone. Using the well-known perspective acceleration effect on astrometric measurements, the true heliocentric radial velocity of a nearby star can be measured with great precision if the time baseline of the astrometric measurements is long enough. Since white dwarfs are compact objects, the gravitational redshift can be quite large (40–80 km/s), and is the predominant source of any shift in wavelength. The mismatch of the true radial velocity with the spectroscopic shift thus leads to a direct measure of the Mass–Radius relation for such objects. Using available catalog information about the known nearby white dwarfs, we estimate how many masses/gravitational redshift measurements can be obtained with an accuracy better than 2%. Nearby white dwarfs are relatively faint objects (10 < V < 15), which can be easily observed by both missions. We also briefly discuss how the presence of a long period planet can mask the astrometric signal of perspective acceleration.