Direct imaging of multiple planets orbiting the star HR 8799.
28 Nov 2008-Science (American Association for the Advancement of Science)-Vol. 322, Iss: 5906, pp 1348-1352
TL;DR: High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units.
Abstract: Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step toward imaging Earth-like planets. Imaging detections are challenging because of the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our solar system.
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TL;DR: In this article, the authors summarize the current empirical knowledge of stellar multiplicity for Main Sequence stars and brown dwarfs, as well as among populations of Pre-Main Sequence stars, and embedded protostars.
Abstract: Stellar multiplicity is an ubiquitous outcome of the star formation process Characterizing the frequency and main characteristics of multiple systems and their dependencies on primary mass and environment is therefore a powerful tool to probe this process While early attempts were fraught with selection biases and limited completeness, instrumentation breakthroughs in the last two decades now enable robust analyses In this review, we summarize our current empirical knowledge of stellar multiplicity for Main Sequence stars and brown dwarfs, as well as among populations of Pre-Main Sequence stars and embedded protostars Clear trends as a function of both primary mass and stellar evolutionary stage are identified that will serve as a comparison basis for numerical and analytical models of star formation
1,261 citations
Cites background from "Direct imaging of multiple planets ..."
...In this context, we note the existence of a handful of planetary-mass objects around intermediate-mass stars (Kalas et al. 2008, Marois et al. 2008) but an apparent dearth of companions around the substellar limit (Janson et al. 2011, Vigan et al. 2012)....
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TL;DR: The HR 8799 planetary system, with its four young giant planets and known cold/warm debris belts, is a unique laboratory in which to study the formation and evolution of giant planets at wide (>10 au) separations.
Abstract: A fourth planet has been discovered orbiting the nearby star HR 8799. Three giant planets had been imaged directly in the near-infrared — thanks to their wide orbits and brightness. The fourth is interior to and about the same mass as the other three. The system, with this additional planet, represents a challenge for current planet formation models, as none of them can explain the in situ formation of all four planets. High-contrast near-infrared imaging of the nearby star HR 8799 has shown three giant planets. Here, the presence of a fourth planet, interior to and about the same mass as the other three, is reported. The system, with this additional planet, represents a challenge for current planet formation models as none of them can explain the in situ formation of all four planets. High-contrast near-infrared imaging of the nearby star HR 8799 has shown three giant planets1. Such images were possible because of the wide orbits (>25 astronomical units, where 1 au is the Earth–Sun distance) and youth ( 10 au) more massive than Jupiter form by way of one-step gravitational instabilities2 or, rather, through a two-step process involving accretion of a core followed by accumulation of a massive outer envelope composed primarily of hydrogen and helium3. Here we report the presence of a fourth planet, interior to and of about the same mass as the other three. The system, with this additional planet, represents a challenge for current planet formation models as none of them can explain the in situ formation of all four planets. With its four young giant planets and known cold/warm debris belts4, the HR 8799 planetary system is a unique laboratory in which to study the formation and evolution of giant planets at wide (>10 au) separations.
1,036 citations
Cites result from "Direct imaging of multiple planets ..."
...Given the current apparent separations of the four planets of HR 8799 and the preferred locations of the inner warm debris disk and the inner edge of the outer cold disk (90 AU)(4), then (1) the indicated 4:1 and 2:1 period resonances between the inner/outer edge of the warm debris belt and planet e, and (2) a 3:2 mean motion resonance of b with the inner edge of the outer cold disk, are both consistent with the observations....
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TL;DR: It is shown that the ~10-million-year-oldβ Pictoris system hosts a massive giant planet, β Pictoris b, located 8 to 15 astronomical units from the star, which confirms that gas giant planets form rapidly within disks and validates the use of disk structures as fingerprints of embedded planets.
Abstract: Here, we show that the ~10-million-year-old β Pictoris system hosts a massive giant planet, β Pictoris b, located 8 to 15 astronomical units from the star. This result confirms that gas giant planets form rapidly within disks and validates the use of disk structures as fingerprints of embedded planets. Among the few planets already imaged, β Pictoris b is the closest to its parent star. Its short period could allow for recording of the full orbit within 17 years.
973 citations
TL;DR: In this article, the authors present new and archival high angular resolution (03 40-75 AU) Submillimeter Array (SMA) observations of the 880 μm (340 GHz) dust continuum emission from 12 transition disks in nearby star-forming regions.
Abstract: Circumstellar disks are thought to experience a rapid transition phase in their evolution that can have a considerable impact on the formation and early development of planetary systems. We present new and archival high angular resolution (03 40-75 AU) Submillimeter Array (SMA) observations of the 880 μm (340 GHz) dust continuum emission from 12 such transition disks in nearby star-forming regions. In each case, we directly resolve a dust-depleted disk cavity around the central star. Using two-dimensional Monte Carlo radiative transfer calculations, we interpret these dust disk structures in a homogeneous, parametric model framework by reproducing their SMA continuum visibilities and spectral energy distributions. The cavities in these disks are large (R cav = 15-73 AU) and substantially depleted of small (~μm-sized) dust grains, although their mass contents are still uncertain. The structures of the remnant material at larger radii are comparable to normal disks. We demonstrate that these large cavities are relatively common among the millimeter-bright disk population, comprising at least 1 in 5 (20%) of the disks in the bright half (and ≥26% of the upper quartile) of the millimeter luminosity (disk mass) distribution. Utilizing these results, we assess some of the physical mechanisms proposed to account for transition disk structures. As has been shown before, photoevaporation models do not produce the large cavity sizes, accretion rates, and disk masses representative of this sample. A sufficient decrease of the dust optical depths in these cavities by particle growth would be difficult to achieve: substantial growth (to meter sizes or beyond) must occur in large (tens of AU) regions of low turbulence without also producing an abundance of small particles. Given those challenges, we suggest instead that the observations are most commensurate with dynamical clearing due to tidal interactions with low-mass companions—very young (~1 Myr) brown dwarfs or giant planets on long-period orbits.
779 citations
Cites background from "Direct imaging of multiple planets ..."
...Moreover, those companions would provide youthful touchstones that could help facilitate a better understanding of their much older counterparts, including the Fomalhaut and HR 8799 planets that orbit just inside their own remnant debris disk rings (Kalas et al. 2008; Marois et al. 2008, 2010)....
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Lawrence Livermore National Laboratory1, Stanford University2, University of California, Berkeley3, University of Toronto4, National Research Council5, Space Telescope Science Institute6, University of Arizona7, Princeton University8, University of California, Los Angeles9, Arizona State University10, University of California, Santa Cruz11, Université de Montréal12, Search for extraterrestrial intelligence13, Ames Research Center14, American Museum of Natural History15, Cornell University16, University of Georgia17, California Institute of Technology18, Johns Hopkins University19
TL;DR: Observations ofBeta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing, and fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions.
Abstract: The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 10(6) at 0.75 arcseconds and 10(5) at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of [Formula: see text] near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017.
754 citations
Cites background from "Direct imaging of multiple planets ..."
...This recipe in various combinations had achieved several notable successes [8][9][10][11][12]....
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References
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TL;DR: The goal of this article is to review the state-of-the-art tracking methods, classify them into different categories, and identify new trends to discuss the important issues related to tracking including the use of appropriate image features, selection of motion models, and detection of objects.
Abstract: The goal of this article is to review the state-of-the-art tracking methods, classify them into different categories, and identify new trends. Object tracking, in general, is a challenging problem. Difficulties in tracking objects can arise due to abrupt object motion, changing appearance patterns of both the object and the scene, nonrigid object structures, object-to-object and object-to-scene occlusions, and camera motion. Tracking is usually performed in the context of higher-level applications that require the location and/or shape of the object in every frame. Typically, assumptions are made to constrain the tracking problem in the context of a particular application. In this survey, we categorize the tracking methods on the basis of the object and motion representations used, provide detailed descriptions of representative methods in each category, and examine their pros and cons. Moreover, we discuss the important issues related to tracking including the use of appropriate image features, selection of motion models, and detection of objects.
5,318 citations
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Abstract: Context. A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than magnitude Hp = 8 to be better, by up to a factor 4, than in the original catalog ue. Aims. The new Hipparcos astrometric catalogue is checked for the quality of the data and the consistency of the formal errors as well as the possible presence of error correlations. The differences with the earlier publication are explained. Methods. The internal errors are followed through the reduction proc ess, and the external errors are investigated on the basis of a comparison with radio observations of a small selection of stars, and the distribution of negative parallaxes. Error co rrelation levels are investigated and the reduction by more than a factor 10 as obtained in the new catalogue is explained. Results. The formal errors on the parallaxes for the new catalogue are confirmed. The presence of a small amount of additional noise , though unlikely, cannot be ruled out. Conclusions. The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the catalogue published in 1997, and provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics.
4,203 citations
TL;DR: In this paper, Cox et al. introduce a general constant and unit model for general constants and units, and discuss atoms and molecules in the solar system, including Planets and Satellites.
Abstract: 1) Introduction. Cox 2)General Constants and Units. Cox 3) Atoms and Molecules. Dappen 4) Spectra. Cowley, et al 5) Radiation. Keady & Kilcrease 6) Radio and Microwave Astronomy. Hjellming 7) Infrared Astronomy. Tokunaga 8) Ultraviolet Astronomy. Teays 9) X-Ray Astronomy. Seward 10) Gamma-Ray and Neutrino Astronomy. Lingenfelter & Rothschild 11) Earth. Schubert & Walterscheid 12) Planets and Satellites. Tholen 13) Solar System Small Bodies. Binzel, et al 14) Sun. Livingston 15) Normal Stars. Drilling & Landolt 16) Stars with Special Characteristics. Fernie 17) Cataclysmic and Symbiotic Variables. Sparks, et al. 18) Supernovae. Wheeler & Bennetti 19) Star Populations and the Solar Neighborhood. Gilmore & Zeilik 20) Theoretical Stellar Evolution. Becker/Pensell/Cox 21) Circumstellar and Interstellar Material. Mathis 22) Star Clusters. Harris & Harris 23) Milky Way Galaxies. Trimble 24) Quasars and Active Galactic Nuclei. Wilkes 25) Clusters and Groups of Galaxies. Bahcall 26) Cosmology. Scott, et al 27) Incidental Tables. Fiala, et al.
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