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N Eliasrosa - One of the best experts on this subject based on the ideXlab platform.
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high luminosity slow ejecta and persistent carbon lines sn 2009dc challenges Thermonuclear Explosion scenarios
Monthly Notices of the Royal Astronomical Society, 2011Co-Authors: S Taubenberger, S Benetti, M Childress, Rudiger Pakmor, Stephan Hachinger, P A Mazzali, V Stanishev, N EliasrosaAbstract:Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s^(−1)). Its light curves decline slowly over half a year after maximum light [Δm_(15)(B)_true= 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after ~200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C ii lines are present until ~2 weeks past maximum, which is unprecedented in Thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ~1.8 M_⊙ of ^(56)Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ~2.8 M_⊙, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible Explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I(1/2) SNe to a core-collapse origin of the Explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.
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high luminosity slow ejecta and persistent carbon lines sn 2009dc challenges Thermonuclear Explosion scenarios
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: S Taubenberger, S Benetti, M Childress, Rudiger Pakmor, Stephan Hachinger, P A Mazzali, V Stanishev, N EliasrosaAbstract:SN 2009dc shares similarities with normal Type Ia supernovae, but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log(L) = 43.47 [erg/s]. Its light curves decline slowly over half a year after maximum light, and the early-time near-IR light curves show secondary maxima, although the minima between the first and second peaks are not very pronounced. Bluer bands exhibit an enhanced fading after ~200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C II lines are present until ~2 weeks past maximum, which is unprecedented in Thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of CSM interaction are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ~1.8 solar masses of 56Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ~2.8 solar masses, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important pre-requisite for producing superluminous SNe Ia. We discuss a number of Explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I 1/2 SNe to a core-collapse origin of the Explosion. None of the models seem capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.
S Taubenberger - One of the best experts on this subject based on the ideXlab platform.
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Deflagrations in hybrid CONe white dwarfs: a route to explain the faint Type Iax supernova 2008ha
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: M. Kromer, Wolfgang Hillebrandt, S. T. Ohlmann, R. Pakmor, A. J. Ruiter, K. S. Marquardt, F. K. Röpke, I. R. Seitenzahl, S. A. Sim, S TaubenbergerAbstract:Stellar evolution models predict the existence of hybrid white dwarfs (WDs) with a carbon–oxygen core surrounded by an oxygen–neon mantle. Being born with masses ∼1.1 M⊙, hybrid WDs in a binary system may easily approach the Chandrasekhar mass (MCh) by accretion and give rise to a Thermonuclear Explosion. Here, we investigate an off-centre deflagration in a near-MCh hybrid WD under the assumption that nuclear burning only occurs in carbon-rich material. Performing hydrodynamics simulations of the Explosion and detailed nucleosynthesis post-processing calculations, we find that only 0.014 M⊙ of material is ejected while the remainder of the mass stays bound. The ejecta consist predominantly of iron-group elements, O, C, Si and S. We also calculate synthetic observables for our model and find reasonable agreement with the faint Type Iax SN 2008ha. This shows for the first time that deflagrations in near-MCh WDs can in principle explain the observed diversity of Type Iax supernovae. Leaving behind a near-MCh bound remnant opens the possibility for recurrent Explosions or a subsequent accretion-induced collapse in faint Type Iax SNe, if further accretion episodes occur. From binary population synthesis calculations, we find the rate of hybrid WDs approaching MCh to be of the order of 1 per cent of the GalacticSN Ia rate.
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high luminosity slow ejecta and persistent carbon lines sn 2009dc challenges Thermonuclear Explosion scenarios
Monthly Notices of the Royal Astronomical Society, 2011Co-Authors: S Taubenberger, S Benetti, M Childress, Rudiger Pakmor, Stephan Hachinger, P A Mazzali, V Stanishev, N EliasrosaAbstract:Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s^(−1)). Its light curves decline slowly over half a year after maximum light [Δm_(15)(B)_true= 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after ~200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C ii lines are present until ~2 weeks past maximum, which is unprecedented in Thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ~1.8 M_⊙ of ^(56)Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ~2.8 M_⊙, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible Explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I(1/2) SNe to a core-collapse origin of the Explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.
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high luminosity slow ejecta and persistent carbon lines sn 2009dc challenges Thermonuclear Explosion scenarios
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: S Taubenberger, S Benetti, M Childress, Rudiger Pakmor, Stephan Hachinger, P A Mazzali, V Stanishev, N EliasrosaAbstract:SN 2009dc shares similarities with normal Type Ia supernovae, but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log(L) = 43.47 [erg/s]. Its light curves decline slowly over half a year after maximum light, and the early-time near-IR light curves show secondary maxima, although the minima between the first and second peaks are not very pronounced. Bluer bands exhibit an enhanced fading after ~200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C II lines are present until ~2 weeks past maximum, which is unprecedented in Thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of CSM interaction are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ~1.8 solar masses of 56Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ~2.8 solar masses, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important pre-requisite for producing superluminous SNe Ia. We discuss a number of Explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I 1/2 SNe to a core-collapse origin of the Explosion. None of the models seem capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.
J E Pringle - One of the best experts on this subject based on the ideXlab platform.
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rs ophiuchi Thermonuclear Explosion or disc instability
Monthly Notices of the Royal Astronomical Society: Letters, 2009Co-Authors: A R King, J E PringleAbstract:Sokoloski, Rupen & Mioduszewski have recently reported evidence that the recurrent nova RS Ophiuchi produced a pair of highly collimated radio jets within days of its 2006 outburst. This suggests that an accretion disc must be present during the outburst. However, in the standard picture of recurrent novae as Thermonuclear events, any such disc must be expelled from the white dwarf vicinity, as the nuclear energy yield greatly exceeds its binding energy. We suggest instead that the outbursts of RS Oph are thermal-viscous instabilities in a disc irradiated by the central accreting white dwarf. The distinctive feature of RS Oph is the very large size of its accretion disc. Given this, it fits naturally into a consistent picture of systems with unstable accretion discs. This picture explains the presence and speed of the jets, the brightness and duration of the outburst, and its rise time and linear decay, as well as the faintness of the quiescence. By contrast, the hitherto standard picture of recurrent Thermonuclear Explosions has a number of severe difficulties. These include the presence of jets, the faintness of quiescence, and the fact the accretion disc must be unstable unless it is far smaller than any reasonable estimate.
M. Kromer - One of the best experts on this subject based on the ideXlab platform.
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The Spectacular Ultraviolet Flash From the Peculiar Type Ia Supernova 2019yvq
Astrophys.J., 2020Co-Authors: A.a. Miller, M.r. Magee, A. Polin, K. Maguire, E. Zimmerman, Y. Yao, J. Sollerman, S. Schulze, D.a. Perley, M. KromerAbstract:Early observations of Type Ia supernovae (SNe Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal Thermonuclear Explosion. We present exquisite observations of SN 2019yvq, the second observed SN Ia, after iPTF 14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN 2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN Ia ( mag at peak) yet featured very high absorption velocities ( km s−1 for Si ii λ6355 at peak). We find that many of the observational features of SN 2019yvq, aside from the flash, can be explained if the explosive yield of radioactive 56Ni is relatively low (we measure ) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN 2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of 56Ni in the outer ejecta, a double-detonation Explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN 2019yvq. In closing, we predict that the nebular spectra of SN 2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [Ca ii] emission, if it was a double detonation, or narrow [O i] emission, if it was due to a violent merger.
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Deflagrations in hybrid CONe white dwarfs: a route to explain the faint Type Iax supernova 2008ha
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: M. Kromer, Wolfgang Hillebrandt, S. T. Ohlmann, R. Pakmor, A. J. Ruiter, K. S. Marquardt, F. K. Röpke, I. R. Seitenzahl, S. A. Sim, S TaubenbergerAbstract:Stellar evolution models predict the existence of hybrid white dwarfs (WDs) with a carbon–oxygen core surrounded by an oxygen–neon mantle. Being born with masses ∼1.1 M⊙, hybrid WDs in a binary system may easily approach the Chandrasekhar mass (MCh) by accretion and give rise to a Thermonuclear Explosion. Here, we investigate an off-centre deflagration in a near-MCh hybrid WD under the assumption that nuclear burning only occurs in carbon-rich material. Performing hydrodynamics simulations of the Explosion and detailed nucleosynthesis post-processing calculations, we find that only 0.014 M⊙ of material is ejected while the remainder of the mass stays bound. The ejecta consist predominantly of iron-group elements, O, C, Si and S. We also calculate synthetic observables for our model and find reasonable agreement with the faint Type Iax SN 2008ha. This shows for the first time that deflagrations in near-MCh WDs can in principle explain the observed diversity of Type Iax supernovae. Leaving behind a near-MCh bound remnant opens the possibility for recurrent Explosions or a subsequent accretion-induced collapse in faint Type Iax SNe, if further accretion episodes occur. From binary population synthesis calculations, we find the rate of hybrid WDs approaching MCh to be of the order of 1 per cent of the GalacticSN Ia rate.
Ewald Muller - One of the best experts on this subject based on the ideXlab platform.
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relativistic collapse and Explosion of rotating supermassive stars with Thermonuclear effects
The Astrophysical Journal, 2012Co-Authors: Pedro J Montero, Hansthomas Janka, Ewald MullerAbstract:We present results of general relativistic simulations of collapsing supermassive stars with and without rotation using the two-dimensional general relativistic numerical code Nada, which solves the Einstein equations written in the BSSN formalism and the general relativistic hydrodynamic equations with high-resolution shock-capturing schemes. These numerical simulations use an equation of state that includes the effects of gas pressure and, in a tabulated form, those associated with radiation and the electron-positron pairs. We also take into account the effect of Thermonuclear energy released by hydrogen and helium burning. We find that objects with a mass of Almost-Equal-To 5 Multiplication-Sign 10{sup 5} M{sub Sun} and an initial metallicity greater than Z{sub CNO} Almost-Equal-To 0.007 do explode if non-rotating, while the threshold metallicity for an Explosion is reduced to Z{sub CNO} Almost-Equal-To 0.001 for objects uniformly rotating. The critical initial metallicity for a Thermonuclear Explosion increases for stars with a mass Almost-Equal-To 10{sup 6} M{sub Sun }. For those stars that do not explode, we follow the evolution beyond the phase of black hole (BH) formation. We compute the neutrino energy loss rates due to several processes that may be relevant during the gravitational collapse of these objects. The peak luminosities of neutrinosmore » and antineutrinos of all flavors for models collapsing to a BH are L{sub {nu}} {approx} 10{sup 55} erg s{sup -1}. The total radiated energy in neutrinos varies between E{sub {nu}} {approx} 10{sup 56} erg for models collapsing to a BH and E{sub {nu}} {approx} 10{sup 45}-10{sup 46} erg for models exploding.« less
