We present the results of a comprehensive assessment of companions to solartype stars. A sample of 454 stars, including the Sun, was selected from the Hipparcos catalog with π > 40 mas, σ π /π < 0.05, 0.5 ≤ B − V ≤ 1.0 (∼ F6-K3), and constrained by absolute magnitude and color to exclude evolved stars. These criteria are equivalent to selecting all dwarf and subdwarf stars within 25 pc with V -band flux between 0.1 and 10 times that of the Sun, giving us a physical basis for the term "solar-type". New observational aspects of this work include surveys for (1) very close companions with long-baseline interferometry at the Center for High Angular Resolution Astronomy (CHARA) Array, (2) close companions with speckle interferometry, and (3) wide proper motion companions identified by blinking multi-epoch archival images. In addition, we include the results from extensive radial-velocity monitoring programs and evaluate companion information from various catalogs covering many different techniques. The results presented here include four new common proper motion companions discovered by blinking archival images. Additionally, the spectroscopic data searched reveal five new stellar companions. Our synthesis of results from many methods and sources results in a thorough evaluation of stellar and brown dwarf companions to nearby Sun-like stars.
Detecting Distant Planets More than 400 planets have been detected outside the solar system, most of which have masses similar to that of the gas giant planet, Jupiter. Borucki et al. (p. 977 , published online 7 January) summarize the planetary findings derived from the first six weeks of observations with the Kepler mission whose objective is to search for and determine the frequency of Earth-like planets in the habitable zones of other stars. The results include the detection of five new exoplanets, which confirm the existence of planets with densities substantially lower than those predicted for gas giant planets.
Abstract. The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its 2-year mission, TESS will employ four wide-field optical charge-coupled device cameras to monitor at least 200,000 main-sequence dwarf stars with I C ≈ 4 − 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from 1 month to 1 year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10 to 100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every 4 months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey (CKS) to study the size distribution of 2025 Kepler planets in fine detail. We detect a factor of ≥2 deficit in the occurrence rate distribution at 1.5-2.0 R ⊕ . This gap splits the population of close-in (P < 100 d) small planets into two size regimes: R P < 1.5 R ⊕ and R P = 2.0-3.0 R ⊕ , with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0 R ⊕ supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5 R ⊕ or smaller with varying amounts of low-density gas that determine their total sizes.
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