Akira Arai
A5009544001- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Parkinson's Disease Mechanisms and Treatments
- Astronomy and Astrophysical Research
- Neurological disorders and treatments
- High-pressure geophysics and materials
- Pulsars and Gravitational Waves Research
- SAS software applications and methods
- X-ray Spectroscopy and Fluorescence Analysis
- Neuroscience and Neuropharmacology Research
- Hair Growth and Disorders
- Radio Astronomy Observations and Technology
- Botulinum Toxin and Related Neurological Disorders
- Peripheral Neuropathies and Disorders
- Neurotransmitter Receptor Influence on Behavior
- Dark Matter and Cosmic Phenomena
- Laser-Plasma Interactions and Diagnostics
- Atmospheric Ozone and Climate
- Atomic and Molecular Physics
- Planetary Science and Exploration
Aomori Prefectural Central Hospital
2016-2025
National Astronomical Observatory of Japan
2022-2024
Kyoto Sangyo University
2013-2024
Subaru (Japan)
2022-2023
University of Hyogo
2013-2018
Tohoku University
1993-2018
Astronomical Observatory
2010-2017
Niigata City General Hospital
2017
Hirosaki University
2003-2014
Kyoto University
2012
Abstract We systematically surveyed period variations of superhumps in SU UMa-type dwarf novae based on newly obtained data and past publications. In many systems, the evolution superhump is found to be composed three distinct stages: an early evolutionary stage with a longer period, middle varying periods, final shorter, stable period. During stage, systems periods less than 0.08 d show positive derivatives. present observational characteristics these stages give greatly improved...
We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of light curve is $\Delta m_{15}(B)=0.65\pm 0.03$, which one slowest among SNe Ia. peak $V$-band absolute magnitude $M_{V}=-19.90\pm 0.15$ mag even if host extinction $A_{V}=0$ mag. It reaches $M_{V}=-20.19\pm 0.19$ $A_{V}=0.29$ as inferred from observed Na {\sc i} D line absorption host. Our $JHK_{s}$-band photometry shows that SN most...
The radio quasar 3C 454.3 underwent an exceptional optical outburst lasting more than 1 year and culminating in spring 2005. maximum brightness detected was R = 12.0, which represents the most luminous state thus far observed (M_B ~ -31.4). In order to follow emission behaviour of source detail, a large multiwavelength campaign organized by Whole Earth Blazar Telescope (WEBT). Continuous optical, near-IR monitoring performed several bands. ToO pointings Chandra INTEGRAL satellites provided...
We report on the correlation between flux, color and polarization variations time scales of days--months in blazars, discuss their universal aspects. performed monitoring 42 blazars optical near-infrared bands from 2008 to 2010 using TRISPEC attached "Kanata" 1.5-m telescope. found that 28 exhibited "bluer-when-brighter" trends whole or a part time-series data sets. This corresponds 88% objects were observed for >10 days. Thus, our observation unambiguously confirmed trend is common emission...
ABSTRACT Maladaptive plasticity at corticostriatal synapses plays an important role in the development of levodopa‐induced dyskinesia. Recently, it has been shown that synaptic is closely linked to morphologic changes dendritic spines. To evaluate spines two types striatal medium spiny neurons, which project internal segment globus pallidus or external pallidus, dyskinesia model, we used 6‐hydroxydopamine‐lesioned rats chronically treated with levodopa. Dendritic were decreased and became...
Objectives [ 18 F] Fluorodeoxyglucose positron emission tomography (FDG PET), a standard tool for evaluating malignancies, can also detect inflammatory lesions. However, its usefulness in muscle lesions polymyositis and dermatomyositis syndromes (PM/DM) has not been established. Methods 33 patients with PM/DM who had undergone FDG PET were retrospectively analysed. uptake was visually evaluated (visually identified uptake, vFDG) 16 regions of the body using mediastinum blood vessels as...
ABSTRACT The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption 10 times, including yearly eruptions from 2008 to 2014. With a measured recurrence period of <?CDATA ${P}_{\mathrm{rec}}=351\pm 13$?> days (we believe the true value be half this) and white dwarf very close Chandrasekhar limit, has become leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations 2013 2014 eruptions, we initiated campaign ensure early...
ABSTRACT We report spectroscopic observations of the resonance lines singly ionized 7 Be in blueshifted absorption line systems found post-outburst spectra two classical novae—V5668 Sgr (Nova Sagittarii 2015 No. 2) and V2944 Oph Ophiuchi 2015). The unstable isotope should have been created during thermonuclear runaway (TNR) these novae decayed to form Li within a short period (a half-life 53.22 days). These confirmations are second third ones following first case V339 Del by Tajitsu et al....
Clinical manifestations of Lyme borreliosis (LB), caused by Borrelia burgdorferi sensu lato (Bbsl), include erythema migrans, neuroborreliosis (LNB), carditis, and arthritis. LB is a notifiable disease in Japan with <30 surveillance-reported cases annually, predominately from Hokkaido Prefecture. However, LB, including LNB, may be under-diagnosed since diagnostic tests are not readily available. We sought to determine if LNB could cause previously undiagnosed encephalitis or meningitis...
Context.In spring 2005 the blazar 3C 454.3 was observed in an unprecedented bright state from near-IR to hard X-ray frequencies. A mm outburst peaked June–July 2005, and it followed by a flux increase at high radio
For prompt optical polarimetry of gamma-ray burst (GRB) afterglow, we require wide-field imaging polarimeter which can produce both Stokes <i>Q</i> and <i>U</i> parameters from only a single exposure, as well quickly-moving telescope enclosure system. HOWPol is an provides four linearly polarized images at position angles 0°, 45°, 90° 135°, i.e., <i>I</i>, <i>Q</i>, <i>U</i>, simultaneously. The key device the wedged double Wollaston prism described by Oliva...
The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio by Whole Earth Blazar Telescope (WEBT) collaboration organized around target-of-opportunity X-ray and soft γ-ray observations with Chandra INTEGRAL in mid-January, additional coverage RXTE Swift XRT. In this paper we focus on results WEBT campaign. source exhibited substantial variability optical flux spectral shape, a characteristic timescale few days....
We investigated the magnitude–phase relation of (162173) 1999 JU3, a target asteroid for JAXA Hayabusa 2 sample return mission. initially employed International Astronomical Union's H–G formalism but found that it fits less well using single set parameters. To improve inadequate fit, we two photometric functions: Shevchenko and Hapke functions. With function, exhibits linear behavior in wide phase angle range (α = 5°–75°) shows weak nonlinear opposition brightening at α < 5°, providing more...
We report observations of the Type Iax supernova (SN Iax) 2012Z at optical and near-infrared (NIR) wavelengths from immediately after explosion until ∼260 days maximum luminosity using Optical Infrared Synergetic Telescopes for Education Research Target-of-Opportunity program Subaru Telescope. found that NIR light curve evolutions color are similar to those SNe 2005hk 2008ha. The absolute magnitudes ( mag mag) rate decline (m15(B) very SN mag, m15(B) 1.6 mag), yet differ significantly 2008ha...
The isotopic ratios are diagnostics for the physico-chemical conditions governing molecular formation. In comets, 14N/15N have been measured from HCN in three comets and CN more than 20 comets. Those enriched 15N compared to Sun by a factor of ∼3, small diversity do not depend on dynamical type origin this high 15N-fractionation is still debate because probably comes only HCN, but also other materials (such as polymers or organic dusts) coma. Consequently, an interpretation cometary quite...
We present optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia supernova (SN) 2014J that appeared in M82. SN exhibits large polarization at shorter wavelengths, e.g., 4.8% B band, which decreases rapidly longer while position angle remains approximately 40° over observed wavelength range. These polarimetric properties suggest is likely predominantly caused by interstellar dust within Further analysis shows peaks a wavelengths much than those obtained for...
We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from $-15.8$ days to $+49.1$ after $B$-band maximum. The decline rate light curve is $Δm_{15}$($B$)$=1.39~\pm~0.05$ mag, which intermediate between normal subluminous SNe Ia, similar that `transitional' SN 2004eo. spectral line profiles also closely resemble those were able observe at very early phase, when it was still rising about three magnitudes fainter than peak. rise time maximum...
Near-infrared (NIR) high-resolution spectroscopy is a fundamental observational method in astronomy. It provides significant information on the kinematics, magnetic fields, and chemical abundances, of astronomical objects embedded or behind highly extinctive clouds at cosmological distances. Scientific requirements have accelerated development technology required for NIR high resolution spectrographs using 10 m telescopes. WINERED near-infrared spectrograph that currently mounted 1.3 Araki...
Abstract WINERED is a novel near-infrared (NIR) high-resolution spectrograph (HRS) that pursues the highest possible sensitivity to realize high-precision spectroscopy in NIR as optical wavelength range. covers 0.9–1.35 μ m ( z , Y and J -bands) with three modes (Wide mode two Hires modes) at maximum spectral resolutions of R = 28,000 70,000. For fulfilling objective, designed an unprecedentedly high instrument throughput (up 50% including quantum efficiency array) times or more than other...