![]() ![]() 2010), a peak in the distribution of planets with orbits of 3 days (Cumming et al. Notable examples include a correlation between planet occurrence and stellar metallicity (Fischer & Valenti 2005 Johnson et al. As more planets were discovered, key physical trends began to emerge. This ease of detection led to a substantial number of early discoveries of ‘hot Jupiters’, but as observing temporal baselines grew longer and as measurement sensitivities improved, the Doppler searches gradually expanded into more of the exoplanet phase space. Hence, the RV detection method is most sensitive to massive, close-in planets. The gravitational velocity perturbation exhibited by the host star is directly related to the mass of the planet and is inversely related to its orbital distance. These targets are ideal, both due to their similarity to our Sun, and due to the abundance of atomic lines in their spectra. The radial velocity method originally focused on finding exoplanets around main sequence FGK stars. During the first decade and a half of the planet discovery era, Doppler surveys expanded their reach and progressed steadily from measurement precisions of 3-10 m/s to 1 m/s as a consequence of improvements in instrument stability and data analysis methods. Prior to the launch of the Kepler telescope in 2009, radial velocity surveys were the dominant method for discovering new exoplanetary systems, with over 400 systems discovered between 19 ( ). The collection of such systems will provide a valuable sample for follow-up programs to characterize their atmospheres through direct imaging. Such surveys, conducted with the optical and infrared echelle spectrometers being built for the TMT, have the potential to complete the census of Earth-mass planets in our stellar neighborhood. With echelle spectrometers approaching the 0.1 m/s radial velocity (RV) measurement precision threshold needed to detect habitable Earth mass planets around Sun-like stars, the continuation of Doppler surveys on state-of-the-art telescopes is imperative. Dashed lines show the typical detectable mass for a given level of Doppler precision, assuming edge-on circular orbits around a solar-type star. Known extrasolar planets and Doppler sensitivity. The TMT’s instrumentation will generate an incredible number of additional discoveries, will drastically expand the kinds of planets we can detect, will provide a rich understanding of these planets’ physical properties, and will potentially yield the first detections of habitable rocky planets. high-precision Doppler measurements, high-precision space-based photometry, and advanced adaptive optics – have driven a large number of exoplanet discoveries. The Thirty Meter Telescope will provide an enormous advance in our ability to identify and characterize extrasolar planets. 2013b), we have yet to conclusively identify a true (potentially habitable) Earth twin around a Sun-like star, let alone determine their frequency. While we have detected both rocky planets and planets located on Earth-like orbits (e.g. density, atmospheric/bulk composition) is much weaker, and is restricted to a handful of favorable cases. Furthermore, our knowledge about the physical properties of exoplanets (e.g. massive planets beyond a few AU, or planets with radii smaller than Earth. However, other classes of planetary systems are almost entirely unexplored – e.g. ![]() We have good constraints on the (high) frequency of planets larger than the Earth with orbital periods less than 100 days and on (the dearth of) the widest-separation, most massive planets (e.g. ![]() However, nearby exoplanets detected by two main methods – Doppler radial velocimetry and transit photometry, and distant exoplanets discovered by microlensing and direct detection, have revealed entirely new classes of planets such as hot Jupiters, Super-Earths, and wide-separation super-jovian planets.Īlthough extrasolar planets discovered thus far have provided important clues about the context within which the Earth and other solar system planets fit, our knowledge of the overall census remains highly incomplete. mass, orbital separation) to those in our own solar system. Some exoplanets have similar properties (i.e. 2013a and references therein).Įxtrasolar planets are a diverse population, spanning a wide range in mass and orbital separation. Statistical studies of exoplanets suggest that planet formation is common, occurring around about half of nearby Sun-like stars (e.g. ![]() Extrasolar planets have been found orbiting the youngest stars to post-main sequence stars and around subsolar to intermediate-mass stars (Kraus & Ireland 2012 Currie et al. In the past few decades, our inventory of known planets has grown from just the eight in our solar system to over several thousand extrasolar planets detected around nearby stars through a variety of techniques (e.g. ![]()
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