A5083300881- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- High-pressure geophysics and materials
- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Galaxies: Formation, Evolution, Phenomena
- Superconducting Materials and Applications
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Fluid Dynamics and Heat Transfer
- X-ray Spectroscopy and Fluorescence Analysis
- Multiple Myeloma Research and Treatments
- Synthesis and properties of polymers
- Ionosphere and magnetosphere dynamics
- Plant and animal studies
- Advanced Sensor Technologies Research
Keio University
2015-2024
Aichi Medical University
2022
Mie University Hospital
2022
The University of Tokyo
1983-2018
Tokyo University of the Arts
2017
Osaka Gas (Japan)
2002-2014
Ministry of the Environment
2014
IHI Corporation (United Kingdom)
2012-2013
IHI Corporation (Japan)
2013
Tokyo Institute of Technology
2007-2012
We propose a new model for progenitor systems of Type Ia supernovae. The consists an accreting white dwarf and lobe-filling, low-mass red giant. When the mass accretion rate exceeds certain critical rate, there is no static envelope solution on dwarf. For this case, we find strong wind solution, which replaces solution. Even if mass-losing star has deep convective envelope, stabilizes transfer until ratio, q, between mass-accreting reaches 1.15, i.e., q < 1.15. A part transferred matter can...
As a promising channel to Type Ia supernovae (SNe Ia), we have proposed symbiotic binary system consisting of white dwarf (WD) and low mass red-giant (RG), where strong winds from the accreting WD play key role increase Chandrasekhar limit. Here propose two new evolutionary processes which make SNe much wider. (1) We first show that + RG close can form wide even with such large initial separation as $a_i \lesssim 40000 R_\odot$. Such consists an AGB star main-sequence (MS) star, is...
We introduce a metallicity dependence of the Type Ia supernova (SN Ia) rate into Galactic and cosmic chemical evolution models. In our SN progenitor scenario, accreting white dwarf (WD) blows strong wind to reach Chandrasekhar mass limit. If iron abundance progenitors is as low [Fe/H] ≲ -1, then too weak for SNe occur. Our model successfully reproduces observed in solar neighborhood. make following predictions that can test this effect:(1) are not found environments such galaxies outskirts...
view Abstract Citations (247) References (62) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optically Thick Winds in Nova Outbursts Kato, Mariko ; Hachisu, Izumi Using the OPAL opacity, we have calculated a sequence of optically thick wind solutions, which mimics time-dependent evolution decay phase novae. Strong winds are driven by large peak opacity and, as result, theoretical timescale nova duration is drastically shortened compared with use old opacity....
We have found a new evolutionary path to Type Ia supernovae (SNe Ia) that has been overlooked in previous work. In this scenario, carbon-oxygen white dwarf (C+O WD) is originated not from an asymptotic giant branch star with C+O core but red helium of ~0.8-2.0 M☉. The star, which formed after the first common envelope evolution, evolves form WD ~0.8-1.1 M☉, transferring part onto secondary main-sequence star. This path, together optically thick wind mass-accreting dwarf, provides much wider...
We revisit the properties of white dwarfs accreting hydrogen-rich matter, by constructing steady state models in which hydrogen shell burning consumes at same rate as dwarf accretes it. obtain for various accretion rates and masses. confirm that these are thermally stable only when is higher than ~10-7 M☉ yr-1. show recent quiescent "surface burning" a much wider range result from use too large zone mass outer part models; must occur thinner layer. A comparison positions on H-R diagram...
Theoretical light curves of four recurrent novae in outburst are modeled to obtain various physical parameters. The objects studied here those with a red giant companion, i.e., T Coronae Borealis, RS Ophiuchi, V745 Scorpii, and V3890 Sagittarii. Our model consists very massive white dwarf (WD) an accretion disk companion. Light-curve calculation includes reflection effects the companion star together shadowing effect on by disk. We also include radiation-induced warping instability reproduce...
We calculate many different nova light curves for a variety of white dwarf masses and chemical compositions, with the assumption that free-free emission from optically thin ejecta dominates continuum flux. show all these are homologous universal law can be derived by introducing "time scaling factor." The template curve has slope flux F ∝ t-1.75 in middle part (from ~2 to ~6 mag below optical maximum), but it declines more steeply, t-3.5, later ~10 mag), where t is time outburst units days....
We present new evolutionary models for Type Ia supernova (SN Ia) progenitors, introducing the mass-stripping effect on a main-sequence (MS) or slightly evolved companion star by winds from mass-accreting white dwarf (WD). The mass stripping attenuates rate of transfer to WD. As result, very massive MS can avoid forming common envelope and thus increase WD up until SN explosion. Including effect, we follow binary evolutions various + systems obtain parameter region in initial donor...
Recent observations of Type Ia supernovae (SNe Ia) suggest that some the progenitor white dwarfs (WDs) had masses up to 2.4–2.8 M☉, highly exceeding Chandrasekhar mass limit. We present a new single degenerate model for SN progenitors, in which WD possibly reaches 2.3–2.7 M☉. Three binary evolution processes are incorporated: optically thick winds from mass-accreting WDs, stripping companion star by winds, and WDs being supported differential rotation. The can increase accretion 2.3 (2.7) M☉...
Stimulated by the recent discovery of 1 yr recurrence period nova M31N 2008-12a, we examined shortest periods hydrogen shell flashes on mass-accreting white dwarfs (WDs). We discuss mechanism that yields a finite minimum for given WD mass. Calculating unstable various masses and mass accretion rates, identified about two months non-rotating 1.38 M☉ with rate 3.6 × 10−7 yr−1. A is realized very massive (≳ 1.3 M☉) WDs high rates 1.5 yr−1). revised our stability limit burning, which will be...
Observations suggest that the properties of Type Ia supernovae (SNe Ia) may depend on environmental characteristics, such as morphology, metallicity, and age host galaxies. The influence these resulting SNe is studied in this Letter. First, it shown carbon mass fraction X(C) C + O white dwarf SN progenitors tends to be smaller for a lower metallicity environment an older binary system. It then suggested variation causes diversity brightness Ia: leads dimmer Ia. Further studies propagation...
We have calculated the mass accumulation efficiency during helium shell flashes on white dwarfs (WDs) of 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, and 1.35 M☉ for accretion rates log He (M☉ yr-1) = -7.4 to -5.8. This is a crucial factor binary evolutions Type Ia supernovae. For less massive WDs (<0.8 M☉) no wind loss occurs, all accreted accumulates WD if Roche lobe size large enough. The takes minimum values in between 1.1 1.2 given rate, as well increases both more WDs. larger than 0.5 ≥ -6.72 masses.
One of the candidates for Type Ia supernova progenitors, recurrent nova RS Ophiuchi, underwent its sixth recorded outburst in 2006 February, and first time a complete light curve supersoft X-rays has been obtained. It shows much earlier emergence longer duration X-ray phase than expected before. These characteristics can be naturally understood when significant amount helium layer piles up beneath hydrogen-burning zone during outburst, suggesting that white dwarf (WD) is effectively growing...
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 present time-dependent nova outburst models with optically thick winds for 1.2 and 1.35$\, M_{\odot }$ white dwarfs (WDs) a mass-accretion rate of $5 \times 10^{-9}\, yr−1 1.3$\, WD $2 yr−1. The X-ray flash occurs 11 d before the optical peak 1.2$\, 2.5 WD. wind mass-loss (1.3$\, WD) reaches $6.4 10^{-5}\, ($7.4 yr−1) at epoch maximum photospheric expansion lowest temperature log Tph (K) = 4.33 (4.35). nuclear energy generated during is lost in form radiation (61% WD; 47% WD),...
Abstract KT Eri is a classical nova that went into outburst in 2009. Recent photometric analysis quiescence indicates relatively longer orbital period of 2.6 days, so could host very bright accretion disk during the like recurrent U Sco, which 1.23 days. We reproduced optical V light curve as well supersoft X-ray outburst, assuming large irradiated wind phase while normal size after winds stop. This result consistent with temporal variation wide-band brightness varies almost...
We have recalculated interior structure of very massive stars uniform chemical composition with the OPAL opacity. Very are found to develop a core-halo extended radiative-envelope. With structure, more star has envelope, then track upper zero-age main-sequence (ZAMS) curves redward in H-R diagram at > 100 M_sol (Z=0.02), >70 (Z=0.05), and 15 for helium ZAMS (X=0., Z=0.02). Therefore, effective temperature is rather low: e.g., 200 star, log T_eff=4.75 (Z=0.004), 4.60 4.46 4.32 (Z=0.10)....
A theoretical light curve for the 1999 outburst of U Scorpii is presented in order to obtain various physical parameters recurrent nova. Our Sco model consists a very massive white dwarf (WD) with an accretion disk and lobe-filling, slightly evolved, main-sequence star (MS). The includes reflection effect by companion together shadowing on disk. early visual (with linear phase t approximately 1-15 days after maximum) well reproduced thermonuclear runaway WD close Chandrasekhar limit...
view Abstract Citations (82) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Why Did the Progenitor of SN 1987A Undergo Blue-Red-Blue Evolution? Saio, Hideyuki ; Kato, Mariko Nomoto, Ken'ichi was progenitor blue and how much hydrogen-rich envelope retained in have been major issues theoretical modeling 1987A. As inferred from observations, very likely evolved first to become a red supergiant then returned blue. We performed systematic...
On the basis of recently developed universal decline law classical novae, we propose prediction formulae for supersoft X-ray on and off times, i.e., t_{X-on} = (10 \pm 1.8) t_3 days t_{X-off} (5.3 1.4) (t_3)^{1.5} 8 < 80 days. We have determined absolute magnitude our free-free emission model light curves derived maximum vs. rate (MMRD) relations. Our theoretical MMRD relations are governed by two parameters, one is white dwarf (WD) mass other initial envelope at a nova outburst; this second...
In the single degenerate (SD) scenario for Type Ia supernova (SN Ia) progenitors, an accreting white dwarf (WD) is expected to undergo a supersoft X-ray source (SSS) phase. Recently, Gilfanov & Bogdán (hereafter GB10) claimed that observed fluxes of early-type galaxies would be too low consistent with prediction SD based on rather simple assumptions. We present realistic evolutionary models systems and calculate durations SSS phases. most cases, WDs spend large fraction time in optically...
Taking into account the rotation of mass-accreting white dwarfs (WDs) whose masses exceed Chandrasekhar mass, we extend our new single degenerate model for progenitors Type Ia supernovae (SNe Ia), accounting two types binary systems: those with a main-sequence companion and red-giant (RG) companion. We present mass distribution WDs exploding as SNe Ia, where WD ranges from 1.38 to 2.3 M☉. These progenitor models are assigned various Ia. A lower range (1.38 M☉ < MWD ≲ 1.5 M☉), which supported...
Another outburst of the recurrent M31 nova M31N 2008-12a was announced in late November 2013. Optical data suggest an unprecedentedly short recurrence time approximately one year. In this Letter we address X-ray properties 2008-12a. We requested Swift monitoring observations shortly after optical discovery. estimated source count rates and extracted spectra from resulting data. The corresponding ultraviolet (UV) also analysed. clearly detected as a bright supersoft (SSS) only six days...
We have calculated the mass accumulation efficiency during helium shell flashes to examine whether or not a carbon-oxygen white dwarf (C+O WD) grows up Chandrasekhar limit ignite Type Ia supernova explosion. It has been frequently argued that luminous super-soft X-ray sources and symbiotic stars are progenitors of SNe Ia. In such systems, C+O WD accretes hydrogen-rich matter from companion burns hydrogen steadily on its surface. The develops layer underneath envelope undergoes periodic...