Author
Motohide Tamura
Other affiliations: Graduate University for Advanced Studies, Subaru, University of Hertfordshire ...read more
Bio: Motohide Tamura is an academic researcher from University of Tokyo. The author has contributed to research in topics: Planet & Exoplanet. The author has an hindex of 85, co-authored 1007 publications receiving 32725 citations. Previous affiliations of Motohide Tamura include Graduate University for Advanced Studies & Subaru.
Topics: Planet, Exoplanet, Stars, Planetary system, Brown dwarf
Papers published on a yearly basis
Papers
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Pontifical Catholic University of Chile1, University of Hertfordshire2, Queen Mary University of London3, European Southern Observatory4, National University of Cordoba5, University of Michigan6, University of La Serena7, University of Florida8, University of São Paulo9, Space Telescope Science Institute10, Universidade Federal do Rio Grande do Sul11, Valparaiso University12, University of Chile13, Chinese Academy of Sciences14, University of Sheffield15, Hungarian Academy of Sciences16, Imperial College London17, National University of La Plata18, University of Concepción19, Max Planck Society20, University of Cambridge21, University of Manchester22, Spanish National Research Council23, University of Southampton24, INAF25, Rochester Institute of Technology26, European Space Research and Technology Centre27, University of Padua28, Andrés Bello National University29, University of Leicester30, Hartebeesthoek Radio Astronomy Observatory31, University of Kent32
TL;DR: In this article, the authors proposed a method to solve the problem of single-input single-output (SISO) communication in the context of artificial neural networks (ANNs).
927 citations
University of Hertfordshire1, University of Leeds2, UK Astronomy Technology Centre3, University of Leicester4, University of Florida5, University of Sheffield6, Chinese Academy of Sciences7, University of Kent8, University of Oxford9, University of Arizona10, University of Southampton11, Macquarie University12, University of Cambridge13, University of Edinburgh14, Cardiff University15
TL;DR: The definitive version of this paper is available at www.blackwellsynergy.com.' Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.13924.x as mentioned in this paper
Abstract: 'The definitive version is available at www.blackwell-synergy.com .' Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.13924.x
547 citations
TL;DR: Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed and could account for the excess of L-amino acids found in the Murchison meteorite and explain the origin of the homochirality of biological molecules.
Abstract: Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed. Circular polarization at shorter wavelengths might have been important in inducing chiral asymmetry in interstellar organic molecules that could be subsequently delivered to the early Earth by comets, interplanetary dust particles, or meteors. This could account for the excess of L-amino acids found in the Murchison meteorite and could explain the origin of the homochirality of biological molecules.
485 citations
TL;DR: In this paper, the authors determined the extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 micron, using point sources detected in the IRSF/SIRIUS near-infrared survey and those in the 2MASS and Spitzer/IRAC/GLIMPSE II catalogs.
Abstract: We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 micron, using point sources detected in the IRSF/SIRIUS near-infrared survey and those in the 2MASS and Spitzer/IRAC/GLIMPSE II catalogs. The central region |l| 3 micron from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS JHKs bands has also been calculated, and a good agreement with that in the MKO system is found. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total to selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law.
446 citations
Kogakuin University1, Tokyo Institute of Technology2, Goddard Space Flight Center3, Osaka University4, University of Louisville5, University of Hawaii6, University of Cincinnati7, Space Science Institute8, The Aerospace Corporation9, Valparaiso University10, Academia Sinica11, Subaru12, Ibaraki University13, Kanagawa University14, Nagoya University15, Princeton University16, University of Nice Sophia Antipolis17, Max Planck Society18, College of Charleston19, University of Tokyo20, Kyoto University21, Graduate University for Advanced Studies22, Instituto Nacional de Técnica Aeroespacial23, California Institute of Technology24, University of Amsterdam25, Institute for the Physics and Mathematics of the Universe26, Hokkaido University27, University of Washington28, Tohoku University29
TL;DR: In this article, high-resolution, H-band, imaging observations, collected with Subaru/HiCIAO, of the scattered light from the transitional disk around SAO 206462 (HD 135344B), reveal the presence of scattered light components as close as 0.2 (approx 28 AU).
Abstract: We present high-resolution, H-band, imaging observations, collected with Subaru/HiCIAO, of the scattered light from the transitional disk around SAO 206462 (HD 135344B). Although previous sub-mm imagery suggested the existence of the dust-depleted cavity at r approximates 46 AU, our observations reveal the presence of scattered light components as close as 0".2 (approx 28 AU) from the star. Moreover, we have discovered two small-scale spiral structures lying within 0".5 (approx 70 AU). We present models for the spiral structures using the spiral density wave theory, and derive a disk aspect ratio of h approx 0.1, which is consistent with previous sub-mm observations. This model can potentially give estimates of the temperature and rotation profiles of the disk based on dynamical processes, independently from sub-mm observations. It also predicts the evolution of the spiral structures, which can be observable on timescales of 10-20 years, providing conclusive tests of the model. While we cannot uniquely identify the origin of these spirals, planets embedded in the disk may be capable of exciting the observed morphology. Assuming that this is the case, we can make predictions on the locations and, possibly, the masses of the unseen planets. Such planets may be detected by future multi-wavelengths observations.
445 citations
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TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
Journal Article•
TL;DR: The first direct detection of gravitational waves and the first observation of a binary black hole merger were reported in this paper, with a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ.
Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160) Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.
4,375 citations
TL;DR: The first extensive catalog of galactic embedded clusters is compiled, finding that the embedded cluster birthrate exceeds that of visible open clusters by an order of magnitude or more indicating a high infant mortality rate for protocluster systems.
Abstract: ▪ Abstract Stellar clusters are born embedded within giant molecular clouds (GMCs) and during their formation and early evolution are often only visible at infrared wavelengths, being heavily obscured by dust. Over the past 15 years advances in infrared detection capabilities have enabled the first systematic studies of embedded clusters in galactic molecular clouds. In this article we review the current state of empirical knowledge concerning these extremely young protocluster systems. From a survey of the literature we compile the first extensive catalog of galactic embedded clusters. We use the catalog to construct the mass function and estimate the birthrate for embedded clusters within ∼2 kpc of the sun. We find that the embedded cluster birthrate exceeds that of visible open clusters by an order of magnitude or more indicating a high infant mortality rate for protocluster systems. Less than 4–7% of embedded clusters survive emergence from molecular clouds to become bound clusters of Pleiades age. Th...
2,949 citations
Massachusetts Institute of Technology1, Harvard University2, Princeton University3, University of Chicago4, Las Cumbres Observatory Global Telescope Network5, University of Copenhagen6, Arizona State University7, Carnegie Institution for Science8, Aarhus University9, University of Birmingham10, Goddard Space Flight Center11, University of Maryland, College Park12, Northern Kentucky University13, Vanderbilt University14, Lowell Observatory15, University of Texas at Austin16, University of Florida17, Max Planck Society18, Tokyo Institute of Technology19, University of California, Berkeley20, University of California, Santa Cruz21, Space Telescope Science Institute22, Johns Hopkins University23, Spanish National Research Council24, Lehigh University25, INAF26, Fisk University27
TL;DR: The Transiting Exoplanet Survey Satellite (TESS) as discussed by the authors will search for planets transiting bright and nearby stars using four wide-field optical charge-coupled device cameras to monitor at least 200,000 main-sequence dwarf stars.
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.
2,604 citations
University of Edinburgh1, Imperial College London2, University of Nottingham3, Durham University4, University of Leicester5, University of Hertfordshire6, UK Astronomy Technology Centre7, Cardiff University8, Queen Mary University of London9, University of Cambridge10, Liverpool John Moores University11
TL;DR: The final version published in MNRAS August 2007 included significant revisions including significant revisions to the original version April 2006.
Abstract: Final published version including significant revisions. Twenty four pages, fourteen figures. Original version April 2006; final version published in MNRAS August 2007
2,562 citations