A5010061828- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Nuclear physics research studies
- Astro and Planetary Science
- Nuclear Physics and Applications
- Astronomical Observations and Instrumentation
- Atomic and Molecular Physics
- Adaptive optics and wavefront sensing
- Quantum Chromodynamics and Particle Interactions
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astronomical and nuclear sciences
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Atmospheric Ozone and Climate
- Advanced NMR Techniques and Applications
- SAS software applications and methods
- Calibration and Measurement Techniques
- Quantum, superfluid, helium dynamics
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
- Planetary Science and Exploration
- Advanced Chemical Physics Studies
Chiba University
2024-2025
Osaka University
2012-2024
RIKEN Nishina Center
2017-2024
Institute of Space and Astronautical Science
2017-2023
Japan Aerospace Exploration Agency
2017-2023
Ministry of Agriculture and Natural Resource
2015-2023
Institut de Physique
2012-2023
Université Paris-Sud
2012-2023
Institut National de Physique Nucléaire et de Physique des Particules
2013-2023
Centre National de la Recherche Scientifique
2013-2023
Based on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. [ABRIDGED], now have 58 microlensed bulge dwarfs subgiants that been homogeneously analysed. The main characteristics sample findings can be drawn are: (i) metallicity distribution (MDF) is wide spans all metallicities between [Fe/H]=-1.9 to +0.6; (ii) dip MDF around solar was apparent our previous smaller...
ABSTRACT We report the results of statistical analysis planetary signals discovered in MOA-II microlensing survey alert system events from 2007 to 2012. determine sensitivity as a function planet–star mass ratio, q , and projected separation, s Einstein radius units. find that mass-ratio is not single power law, but has change slope at ∼ 10 −4 corresponding ∼20 M ⊕ for median host-star ∼0.6 . significant 23 1474 are well-characterized by data alone. Data other groups used only characterize...
Abstract We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). used Hubble Space Telescope (HST) to carry out precise astrometry source star long-duration ( t E ≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in direction Galactic bulge. HST imaging, conducted at eight epochs over interval 6 yr, reveals a clear relativistic astrometric deflection...
Abstract We present the first measurement of mass function free-floating planets (FFPs), or very wide orbit down to an Earth mass, from MOA-II microlensing survey in 2006–2014. Six events are likely be due with Einstein radius crossing times t E < 0.5 days, and shortest has = 0.057 ± 0.016 days angular θ 0.90 0.14 μ as. measure detection efficiency depending on both image-level simulations for time. These short well modeled by a power-law function, <mml:math...
We present the first microlensing candidate for a free-floating exoplanet–exomoon system, MOA-2011-BLG-262, with primary lens mass of Mhost ∼ 4 Jupiter masses hosting sub-Earth moon. The argument an exomoon hinges on system being relatively close to Sun. data constrain product MLπrel where ML is and πrel lens–source relative parallax. If nearby (large πrel), then small (a few masses) companion sub-Earth-mass exomoon. best-fit solution has large proper motion, μrel = 19.6 ± 1.6 mas yr−1,...
We present a detailed elemental abundance study of 90 F and G dwarf, turn-off, subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages abundances for 11 elements (Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Zn, Y Ba) have been determined. Four main findings are presented: (1) wide metallicity distribution with distinct peaks at [Fe/H] = −1.09, −0.63, −0.20, + 0.12, 0.41; (2) ahigh fraction intermediate-age to young where > 0...
We present the first example of binary microlensing for which parameter measurements can be verified (or contradicted) by future Doppler observations. This test is made possible a confluence two relatively unusual circumstances. First, lens bright enough (I=15.6) to permit measurements. Second, we measure not only usual 7 binary-lens parameters, but also 'microlens parallax' (which yields mass) and components instantaneous orbital velocity. Thus measure, effectively, 6 'Kepler+1' parameters...
[ABRIDGED] Based on high-resolution (R~42000 to 48000) and high signal-to-noise (S/N~50 150) spectra obtained with UVES/VLT, we present detailed elemental abundances (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, Ba) stellar ages for 26 microlensed dwarf subgiant stars in the Galactic bulge. The analysis is based equivalent width measurements standard 1-D LTE MARCS model atmospheres. We also NLTE Li line synthesis of 7Li at 670.8 nm. show that bulge metallicity distribution (MDF)...
We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm relative proper motion prediction due to light curve signal observed this event. This (and companion Keck result) provide first confirmation a signal, deviation was only 2%. The follow-up determine flux host star in multiple passbands remove model ambiguity caused by sparse sampling part curve. leads precise...
The half-lives of 20 neutron-rich nuclei with Z=27-30 have been measured at the RIBF, including five new (76)Co(21.7(-4.9)(+6.5) ms), (77)Co(13.0(-4.3)(+7.2) (79)Ni(43.0(-7.5)(+8.6) (80)Ni(23.9(-17.2)(+26.0) and (81)Cu(73.2 ± 6.8 ms). In addition, (73-75)Co, (74-78)Ni, (78-80)Cu, (80-82)Zn were determined higher precision than previous works. Based on these results, a systematic study β-decay has carried out, which suggests sizable magicity for both proton number Z = 28 neutron N=50 in (78)Ni.
We present the discovery and mass measurement of cold, low-mass planet MOA-2009-BLG-266Lb, performed with gravitational microlensing method. This has a mp = 10.4 ± 1.7 M⊕ orbits star M⋆ 0.56 0.09 M☉ at semimajor axis AU an orbital period yrs. The host measurements are enabled by parallax effect, which is seen primarily in light curve distortion due to motion Earth. But analysis also demonstrates capability measure Deep Impact (or EPOXI) spacecraft heliocentric orbit. distance similar...
We present a statistical analysis of the first four seasons from "second-generation" microlensing survey for extrasolar planets, consisting near-continuous time coverage 8 deg$^2$ Galactic bulge by OGLE, MOA, and Wise surveys. During this period, 224 events were observed all three groups. Over 12% showed deviation single-lens microlensing, $\sim$1/3 those anomaly is likely caused planetary companion. For each we have performed numerical ray-tracing simulations to calculate detection...
Because of the development large-format, wide-field cameras, microlensing surveys are now able to monitor millions stars with sufficient cadence detect planets. These new discoveries will span full range significance levels including planetary signals too small be distinguished from noise. At present, we do not understand where threshold is for detecting MOA-2011-BLG-293Lb first planet published surveys, and it also has substantial follow-up observations. This robustly detected in...
Impolite planet ignores host's partner Many known exoplanets (planets outside our own solar system) are hosted by binary systems that contain two stars. These planets normally circle around both of their Using microlensing data taken with a worldwide network telescopes, Gould et al. found twice the mass Earth circles just one pair The same approach has potential to uncover other similar star and help illuminate some mysteries formation. Science , this issue p. 46
We present the analysis of first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with mass ratio $q \approx 3.4\times10^{-4}$, but there an additional due to lens mass, either another or star. find acceptable light curve fits two classes models: 2-planet models (with single host star) and models. The also reveals significant parallax effect, which constrains system be $M_L 0.7 M_\odot$. Hubble Space Telescope images resolve...
We report the detection of a Cold Neptune m_planet=21+/-2MEarth orbiting 0.38MSol M dwarf lying 2.5-3.3 kpc toward Galactic center as part campaign combining ground-based and Spitzer observations to measure distribution planets. This is first time that complex real-time protocols described by Yee et al. (2015), which aim maximize planet sensitivity while maintaining sample integrity, have been carried out in practice. Multiple survey follow-up teams successfully combined their efforts within...
Abstract We report the discoveries of low-mass free-floating planet (FFP) candidates from analysis 2006–2014 MOA-II Galactic bulge survey data. In this data set, we found 6111 microlensing and identified a statistical sample consisting 3535 high-quality single-lens events with Einstein radius crossing times in range 0.057 < t E /days 757, including 13 that show clear finite-source effects angular radii 0.90 θ / μ as 332.54. Two 12 1 day have significant effects, one event, MOA-9y-5919, =...
We present measurements of the microlensing optical depth and event rate toward Galactic Bulge based on two years MOA-II survey. This sample contains ~1000 events, with an Einstein Radius crossing time t_E < 200 days between -5 <l< 10 degree -7 <b< -1 degree. Our analysis uses 474 events well defined parameters. In central fields |l|< 5 degree, we find rates \Gamma = [2.39+/-1.1]e^{[0.60\pm0.05](3-|b|)}x 10^{-5}/star/yr \tau_{200} [2.35+/-0.18]e^{[0.51+/-0.07](3-|b|)}x 10^{-6} for 427 using...
Observations of accretion disks around young brown dwarfs (BDs) have led to the speculation that they may form planetary systems similar normal stars. While there been several detections planetary-mass objects BDs (2MASS 1207-3932 and 2MASS 0441-2301), these companions relatively large mass ratios projected separations, suggesting formed in a manner analogous stellar binaries. We present discovery object orbiting field BD via gravitational microlensing, OGLE-2012-BLG-0358Lb. The system is...
We report discovery of the lowest mass ratio exoplanet to be found by microlensing method in light curve event OGLE 2016–BLG–1195. This planet revealed itself as a small deviation from single lens profile an examination survey data. The duration planetary signal is ∼2.5 h. measured its host star q = 4.2 ± 0.7 × 10−5. further estimate that system likely comprise cold ∼3 Earth ∼2 au wide orbit around 0.2 Solar at overall distance 7.1 kpc.
We present the discovery of first Neptune analog exoplanet or super-Earth with Neptune-like orbit, MOA-2013-BLG-605Lb. This planet has a mass similar to that and it orbits at $9\sim 14$ times expected position snow-line, $a_{\rm snow}$, which is Neptune's separation $ 11\,a_{\rm snow}$ from Sun. The planet/host-star ratio $q=(3.6\pm0.7)\times 10^{-4}$ projected normalized by Einstein radius $s=2.39\pm0.05$. There are three degenerate physical solutions two these due new type degeneracy in...