scholarly journals Type IA Supernovae

1992 ◽  
Vol 151 ◽  
pp. 225-234
Author(s):  
J. Craig Wheeler
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Type Ia Supernovae ◽  
Low Velocity ◽  
Severe Problem ◽  
Transfer Rates ◽  
Secular Evolution ◽  
Thermonuclear Explosion ◽  
Type Ia ◽  
Ia Supernovae

Spectral calculations show that a model based on the thermonuclear explosion of a degenerate carbon/oxygen white dwarf provides excellent agreement with observations of Type Ia supernovae. Identification of suitable evolutionary progenitors remains a severe problem. General problems with estimation of supernova rates are outlined and the origin of Type Ia supernovae from double degenerate systems are discussed in the context of new rates of explosion per H band luminosity, the lack of observed candidates, and the likely presence of H in the vicinity of some SN Ia events. Re-examination of the problems of triggering Type Ia by accretion of hydrogen from a companion shows that there may be an avenue involving cataclysmic variables, especially if extreme hibernation occurs. Novae may channel accreting white dwarfs to a unique locus in accretion rate/mass space. Systems that undergo secular evolution to higher mass transfer rates could lead to just the conditions necessary for a Type Ia explosion. Tests involving fluorescence or absorption in a surrounding circumstellar medium and the detection of hydrogen stripped from a companion, which should appear at low velocity inside the white dwarf ejecta, are suggested. Possible observational confirmation of the former is described.

scholarly journals Recurrent Novae: What Do We Know about Them?

2011 ◽  
Vol 7 (S281) ◽  
pp. 154-161 ◽  
Author(s):  
G. C. Anupama
Keyword(s):  
White Dwarf ◽  
Binary Systems ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae ◽  
Nova Outbursts ◽  
Nova Outburst

AbstractRecurrent novae (RNe) belong to the group of cataclysmic variables that exhibit nova outbursts at intervals on the order of decades. They are rare, with 10 Galactic RNe known to date. Two are known in the LMC, while there are a few suspected RNe in M31. Nova outburst models require a high accretion rate on a massive white dwarf to explain the recurring nova outbursts, making this class of objects one of the most likely progenitor binary systems of Type Ia supernovae. The observational properties of the known Galactic recurrent novae are presented here, together with some discussion on the recent outbursts of RS Ophiuchi (2006), U Scorpii (2010), and T Pyxidis (2011).

scholarly journals Type Ia Supernova Models and Progenitor Scenarios

2011 ◽  
Vol 7 (S281) ◽  
pp. 253-260
Author(s):  
Ken'ichi Nomoto ◽  
Yasuomi Kamiya ◽  
Naohito Nakasato
Keyword(s):  
White Dwarf ◽  
Emission Lines ◽  
Type Ia Supernovae ◽  
Theoretical Studies ◽  
Low Velocity ◽  
Dynamical Phase ◽  
Type Ia ◽  
Recent Developments ◽  
Ia Supernovae ◽  
Interesting Constraint

AbstractWe review some recent developments in theoretical studies on the connection between the progenitor systems of Type Ia supernovae (SNe Ia) and the explosion mechanisms. (1) DD-subCh: In the merging of double C+O white dwarfs (DD scenario), if the carbon detonation is induced near the white dwarf (WD) surface in the early dynamical phase, it could result in the (effectively) sub-Chandrasekhar mass explosion. (2) DD-Ch: If no surface C-detonation is ignited, the WD could grow until the Chandrasekhar mass is reached, but the outcome depends on whether the quiescent carbon shell burning is ignited and burns C+O into O+Ne+Mg. (3) SD-subCh: In the single degenerate (SD) scenario, if the He shell-flashes grow strong to induce a He detonation, it leads to the sub-Chandra explosion. (4) SD-Ch: If the He-shell flashes are not strong enough, they still produce interesting amounts of Si and S near the surface of the C+O WD before the explosion. In the Chandra mass explosion, the central density is high enough to produce electron capture elements, e.g., stable 58Ni. Observations of the emission lines of Ni in the nebular spectra provides useful diagnostics of the sub-Chandra vs. Chandra issue. The recent observations of relatively low velocity carbon near the surface of SNe Ia provide also an interesting constraint on the explosion models.

scholarly journals Ultra-soft Sources as Type Ia Supernovae Progenitors

2011 ◽  
Vol 7 (S281) ◽  
pp. 136-139
Author(s):  
Kelly Lepo ◽  
Marten van Kerkwijk
Keyword(s):  
White Dwarf ◽  
Planetary Nebula ◽  
Type Ia Supernovae ◽  
Transfer Rates ◽  
Upper Limit ◽  
Processed Material ◽  
Null Result ◽  
Type Ia ◽  
Nuclear Burning ◽  
Ia Supernovae

AbstractMissing from the usual considerations of nuclear burning white dwarfs as Type Ia supernovae progenitors are systems with very higher mass transfer rates, where more material than is needed for steady burning accretes on the white dwarf. This will expand the photosphere of the white dwarf, causing it to emit at longer wavelengths. Thus, we propose the name ultra-soft source (USS) for these objects.We present a VLT/FLAMES survey looking for USSs in the SMC, selected to be bright in the far UV and with blue far UV-V colors. While we find some unusual objects, and recover known planetary nebulae and WR stars, we detect no objects with strong He II lines, which should be a signature of USSs. This null result either puts an upper limit on the number of USSs in the SMC, or shows that we do not understand what the optical spectra of such objects will look like.We also discuss the unusual LMC [WN] planetary nebula LMC N66 as a possible example of a USS. It has a luminosity consistent with that expected, and its spectra show incompletely CNO-processed material — strong helium lines, some hydrogen, enhanced nitrogen and depleted carbon. It also shows periodic outbursts. USSs may resemble N66 in quiescence. However, it lacks a FUV excess, contrary to our predictions.

scholarly journals Gravitational Collapse versus Thermonuclear Explosion of Degenerate Stellar Cores

1994 ◽  
Vol 147 ◽  
pp. 186-213
Author(s):  
J. Isern ◽  
R. Canal
Keyword(s):  
Neutron Star ◽  
White Dwarfs ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Radioactive Elements ◽  
Border Line ◽  
Thermonuclear Explosion ◽  
Type Ia ◽  
Γ Rays ◽  
Ia Supernovae

AbstractIn this paper we review the behavior of growing stellar degenerate cores. It is shown that ONeMg white dwarfs and cold CO white dwarfs can collapse to form a neutron star. This collapse is completely silent since the total amount of radioactive elements that are expelled is very small and a burst of γ-rays is never produced. In the case of an explosion (always carbonoxygen cores), the outcome fits quite well the observed properties of Type Ia supernovae. Nevertheless, the light curves and the velocities measured at maximum are very homogeneous and the diversity introduced by igniting at different densities is not enough to account for the most extreme cases observed. It is also shown that a promising way out of this problem could be the He-induced detonation of white dwarfs with different masses. Finally, we outline that the location of the border line which separetes explosion from collapse strongly depends on the input physics adopted.

scholarly journals Are the Precursors of Type Ia Supernovae Double Degenerate Mergers?

2004 ◽  
Vol 194 ◽  
pp. 111-112
Author(s):  
Lilia Ferrario
Keyword(s):  
Neutron Stars ◽  
White Dwarf ◽  
White Dwarfs ◽  
Observational Evidence ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae

AbstractI argue that the observational evidence for white dwarf-white dwarf mergers supports the view that they give rise to ultra-massive white dwarfs or neutron stars through accretion induced collapse. The implications for the progenitors of Type Ia SNe are discussed.

scholarly journals Symbiotic Stars as Possible Progenitors of SNe Ia: Binary Parameters and Overall Outlook

2011 ◽  
Vol 7 (S281) ◽  
pp. 162-165 ◽  
Author(s):  
J. Mikołajewska
Keyword(s):  
White Dwarf ◽  
Physical Characteristics ◽  
Type Ia Supernovae ◽  
Symbiotic Stars ◽  
Type Ia ◽  
Red Giant ◽  
Ia Supernovae

AbstractSymbiotic stars are interacting binaries in which the first-formed white dwarf accretes and burns material from a red giant companion. This paper aims at presenting physical characteristics of these objects and discussing their possible link with progenitors of Type Ia supernovae.

scholarly journals Effects of Rotation on Helium Accreting White Dwarf

2004 ◽  
Vol 215 ◽  
pp. 571-572 ◽  
Author(s):  
S.-C. Yoon ◽  
N. Langer
Keyword(s):  
Angular Momentum ◽  
White Dwarf ◽  
Spherical Symmetry ◽  
Binary Systems ◽  
Close Binary ◽  
Type Ia Supernovae ◽  
Classical Studies ◽  
Type Ia ◽  
Effects Of Rotation ◽  
Ia Supernovae

Classical studies of accreting white dwarfs have assumed spherical symmetry. However, it is believed that in close binary systems the transfered matter carries angular momentum to spin up the accreting star. Here, we present preliminary results of CO white dwarf models which accrete helium rich matter with effects of rotation considered, in the context of the Sub-Chandrasekhar mass scenario for Type Ia supernovae.

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