scholarly journals The Mass of the White Dwarf in the Recurrent Nova CI Aquilae

2011 ◽  
Vol 7 (S281) ◽  
pp. 193-194
Author(s):  
D. I. Sahman ◽  
V. S. Dhillon
Keyword(s):  
High Mass ◽  
Mass Ratio ◽  
Time Resolved ◽  
Secondary Star ◽  
Type Ia ◽  
Mass Estimate ◽  
Recurrent Nova ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Absorption Features

AbstractIf recurrent novae (RNe) are progenitors of Type Ia Supernovae (SNe Ia), their white dwarfs (WD) must have masses close to the Chandrasekhar limit. The most reliable means of determining WD masses in RNe is dynamically, via radial-velocity and rotational-broadening measurements of the companion star. Such measurements require the system to be both eclipsing and to show absorption features from the secondary star. The only other reliable RNe mass estimate is for U Sco, which has a WD mass of 1.55 ± 0.24 M⊙ (Thoroughgood et al. 2001).We present new time-resolved, intermediate-resolution spectroscopy of the eclipsing RN CI Aql during quiescence. We find the mass of the WD to be 1.02 ± 0.08 M⊙ and the mass of the secondary star to be 2.41 ± 0.2 M⊙. We estimate the radius of the secondary to be 2.10 ± 0.07 R⊙. The high mass ratio of q=2.37 ± 0.15 and the high secondary star mass suggests that mass transfer occurs on a thermal timescale. We suggest that CI Aql is evolving into a supersoft x-ray source, and ultimately will explode as an SN Ia.

scholarly journals The Changing Nature of QU Carinae: SN Ia Progenitor or a Hoax?

2011 ◽  
Vol 7 (S281) ◽  
pp. 149-153
Author(s):  
Stella Kafka
Keyword(s):  
Supernova Explosion ◽  
High Resolution Spectroscopy ◽  
High Mass ◽  
Type Ia Supernovae ◽  
Variable Nature ◽  
Type Ia ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Mass Accumulation

AbstractThe race to the elusive Type Ia supernovae (SNe Ia) progenitors is at its zenith, with numerous clues from SNe Ia ejecta and a dearth of observational candidates. Still, the single degenerate channel is a viable route of mass accumulation onto a white dwarf to the Chandrasekhar limit. I present long-term high resolution spectroscopy of QU Carinae, one of the most promising single degenerate SNe Ia progenitors. I discuss its highly variable nature and compare it to current scenarios for mass accumulation onto high-mass white dwarfs, eventually leading to WD detonation and to a supernova explosion.

scholarly journals Spectral analysis of the binary nucleus of the planetary nebula Hen 2-428 – first results

2018 ◽  
Vol 27 (1) ◽  
pp. 57-61 ◽  
Author(s):  
Nicolle L. Finch ◽  
Nicole Reindl ◽  
Martin A. Barstow ◽  
Sarah L. Casewell ◽  
Stephan Geier ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
High Mass ◽  
Type Ia ◽  
First Results ◽  
Quantitative Spectral Analysis ◽  
Alternative Scenarios ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Hubble Time ◽  
Interesting System

Abstract Identifying progenitor systems for the double-degenerate scenario is crucial to check the reliability of type Ia supernovae as cosmological standard candles. Santander-Garcia et al. (2015) claimed that Hen 2-428 has a doubledegenerate core whose combined mass significantly exceeds the Chandrasekhar limit. Together with the short orbital period (4.2 hours), the authors concluded that the system should merge within a Hubble time triggering a type Ia supernova event. Garcia-Berro et al. (2016) explored alternative scenarios to explain the observational evidence, as the high mass conclusion is highly unlikely within predictions from stellar evolution theory. They conclude that the evidence supporting the supernova progenitor status of the system is premature. Here we present the first quantitative spectral analysis of Hen 2-428which allows us to derive the effective temperatures, surface gravities and helium abundance of the two CSPNe based on state-of-the-art, non-LTE model atmospheres. These results provide constrains for further studies of this particularly interesting system.

scholarly journals A closer look at non-interacting He stars as a channel for producing the old population of type Ia supernovae

2020 ◽  
Vol 641 ◽  
pp. A20
Author(s):  
Zhengwei Liu ◽  
Richard J. Stancliffe
Keyword(s):  
Binary Systems ◽  
Type Ia Supernovae ◽  
Population Synthesis ◽  
Thermonuclear Explosion ◽  
Delay Times ◽  
Type Ia ◽  
Binary Evolution ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Almost All

The nature of the progenitors of type Ia supernovae (SNe Ia) remains a mystery. Binary systems consisting of a white dwarf (WD) and a main-sequence (MS) donor are potential progenitors of SNe Ia, in which a thermonuclear explosion of the WD may occur when its mass reaches the Chandrasekhar limit during accretion of material from a companion star. In the present work, we address theoretical rates and delay times of a specific MS donor channel to SNe Ia, in which a helium (He) star + MS binary produced from a common envelope event subsequently forms a WD + MS system without the He star undergoing mass transfer by Roche lobe overflow. By combining the results of self-consistent binary evolution calculations with population synthesis models, we find that the contribution of SNe Ia in this channel is around 2.0 × 10−4 yr−1. In addition, we find that delay times of SNe Ia in this channel cover a range of about 1.0–2.6 Gyr, and almost all SNe Ia produced in this way (about 97%) have a delay time of ≳1 Gyr. While the rate of SN Ia in this work is about 10% of the overall SN Ia rate, the channel represents a possible contribution to the old population (1–3 Gyr) of observed SNe Ia.

scholarly journals White dwarf accretion and type Ia supernovae

2012 ◽  
Vol 8 (S290) ◽  
pp. 117-120
Author(s):  
Z. Han ◽  
X. Chen
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Type Ia Supernovae ◽  
Lower Mass ◽  
Type Ia ◽  
Chandrasekhar Limit ◽  
Ia Supernovae

AbstractType Ia supernovae (SNe Ia) are believed to be thermonuclear explosions of carbon-oxygen white dwarfs at a mass close to the Chandrasekhar limit. However, a white dwarf at birth has a significantly lower mass and needs to accrete mass to grow to the limit for the explosion. Various progenitor models have been proposed and those models play an important role in our understanding of SNe Ia and cosmology.

scholarly journals Circumstellar Material in Type Ia Supernovae via Sodium Absorption Features

Science ◽  
2011 ◽  
Vol 333 (6044) ◽  
pp. 856-859 ◽  
Author(s):  
A. Sternberg ◽  
A. Gal-Yam ◽  
J. D. Simon ◽  
D. C. Leonard ◽  
R. M. Quimby ◽  
...  
Keyword(s):  
Sodium Absorption ◽  
Type Ia Supernovae ◽  
Circumstellar Material ◽  
Type Ia ◽  
Ia Supernovae ◽  
Absorption Features

scholarly journals Novae and Accreting White Dwarfs as Progenitors of Type Ia Supernovae

2011 ◽  
Vol 7 (S281) ◽  
pp. 172-180
Author(s):  
Mariko Kato
Keyword(s):  
White Dwarfs ◽  
Main Sequence ◽  
Accretion Rate ◽  
Type Ia Supernovae ◽  
Light Curve Analysis ◽  
X Ray ◽  
Type Ia ◽  
Recurrent Nova ◽  
Red Giant ◽  
Ia Supernovae

AbstractI review various phenomena associated with mass-accreting white dwarfs (WDs) in relation to progenitors of Type Ia supernovae (SNe Ia). The WD mass can be estimated from light curve analysis in multiwavelength bands based on the theory of optically thick winds. In the single degenerate scenario of SNe Ia, two main channels are known, i.e., WD + main sequence (MS) channel and WD + red giant (RG) channel. In each channel, a typical binary undergoes three evolutionary stages before explosion, i.e., the wind phase, supersoft X-ray source (SSS) phase, and recurrent nova phase, in this order because the accretion rate decreases with time as the companion mass decreases. For some accreting WDs we can identify the corresponding stage of evolution. Intermittent supersoft X-ray sources like RX J0513.9−6951 and V Sge correspond to wind phase objects. For the SSS phase, CAL 87-type objects correspond to the WD+MS channel. For the WD + RG channel, soft X-ray observations of early type galaxies give statistical evidence of SSS phase binaries. Recurrent novae of U Sco-type and RS Oph-type correspond to the WD + MS channel and WD + RG channel, respectively. The majority of recurrent novae host a very massive WD (≳ 1.35 M⊙) and often show a plateau phase in their optical light curves corresponding to the long-lasting supersoft X-ray phase. These properties are indications of increasing WD masses.

scholarly journals PSR J1012+5307: a millisecond pulsar with an extremely low-mass white dwarf companion

2020 ◽  
Vol 494 (3) ◽  
pp. 4031-4042 ◽  
Author(s):  
D Mata Sánchez ◽  
A G Istrate ◽  
M H van Kerkwijk ◽  
R P Breton ◽  
D L Kaplan
Keyword(s):  
White Dwarf ◽  
Binary Interaction ◽  
Mass Ratio ◽  
Photometric Analysis ◽  
Unique Path ◽  
Mass Estimate ◽  
Low Mass ◽  
Binary Evolution ◽  
Absorption Features ◽  
Main Factor

ABSTRACT Binaries harbouring millisecond pulsars (MSPs) enable a unique path to determine neutron star (NS) masses: radio pulsations reveal the motion of the NS, while that of the companion can be characterized through studies in the optical range. PSR J1012+5307 is an MSP in a 14.5-h orbit with a helium-core white dwarf (WD) companion. In this work we present the analysis of an optical spectroscopic campaign, where the companion star absorption features reveal one of the lightest known WDs. We determine a WD radial velocity semi-amplitude of $K_2 = 218.9 \pm 2.2\, \rm km\, s^{-1}$, which combined with that of the pulsar derived from the precise radio timing, yields a mass ratio of q = 10.44 ± 0.11. We also attempt to infer the WD mass from observational constraints using new binary evolution models for extremely low-mass (ELM) WDs, but find that they cannot reproduce all observed parameters simultaneously. In particular, we cannot reconcile the radius predicted from binary evolution with the measurement from the photometric analysis ($R_{\rm WD}=0.047_{-0.002}^{+0.003}\, \mathrm{ R}_{\odot }$). Our limited understanding of ELM WD evolution, which results from binary interaction, therefore comes as the main factor limiting the precision with which we can measure the mass of the WD in this system. Our conservative WD mass estimate of $M_{\rm WD} = 0.165 \pm 0.015\, \mathrm{ M}_{\rm \odot }$, along with the mass ratio enables us to infer a pulsar mass of $M_{\rm NS} = 1.72 \pm 0.16\, \mathrm{ M}_{\rm \odot }$. This value is clearly above the canonical $\sim 1.4\, \mathrm{ M}_{\rm \odot }$, therefore adding PSR J1012+5307 to the growing list of massive MSPs.

scholarly journals The WD+He star binaries as the progenitors of type Ia supernovae

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Bo Wang ◽  
Dongdong Liu
Keyword(s):  
Parameter Space ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Type Ia Supernovae ◽  
Population Synthesis ◽  
Accretion Rates ◽  
Type Ia ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Modest Reduction

AbstractEmploying the MESA stellar evolution code, we computed He accretion onto carbon-oxygen white dwarfs (CO WDs).We found two possible outcomes for models in which the WD steadily grows in mass towards the Chandrasekhar limit. For relatively low He-accretion rates carbon ignition occurs in the center, leading to a type Ia supernova (SN Ia) explosion, whereas for relatively high accretion rates carbon is ignited off-center, probably leading to collapse. Thus the parameter space producing SNe Ia is reduced compared to what was assumed in earlier papers, in which the possibility of off-center ignition was ignored. We then applied these results in binary population synthesis modelling, finding a modest reduction in the expected birthrate of SNe Ia resulting from the WD+He star channel.

scholarly journals The formation of type Ia supernovae from carbon–oxygen–silicon white dwarfs

2020 ◽  
Vol 495 (1) ◽  
pp. 1445-1460 ◽  
Author(s):  
Chengyuan Wu ◽  
Bo Wang ◽  
Xiaofeng Wang ◽  
Keiichi Maeda ◽  
Paolo Mazzali
Keyword(s):  
High Velocity ◽  
Accretion Rate ◽  
Outer Part ◽  
Type Ia Supernovae ◽  
Spectral Evolution ◽  
Convective Mixing ◽  
Type Ia ◽  
Chandrasekhar Limit ◽  
Ia Supernovae ◽  
Carbon Burning

ABSTRACT The carbon–oxygen white dwarf (CO WD)+He star channel is thought to be one of the promising scenarios that produce young type Ia supernovae (SNe Ia). Previous studies found that if the mass-accretion rate is greater than a critical value, the He-accreting CO WD will undergo inwardly propagating (off-centre) carbon ignition when it increases its mass close to the Chandrasekhar limit. Previous works supposed that the inwardly propagating carbon flame would reach the centre, leading to the production of an oxygen–neon (ONe) WD that may collapse into a neutron star but not an SN Ia. However, it is still uncertain how the carbon flame propagates under the effect of mixing mechanisms. In the present work, we aim to investigate the off-centre carbon burning of He-accreting CO WDs by considering the effect of convective mixing. We found that the temperature of the flame is high enough to burn the carbon into silicon-group elements in the outer part of the CO core even if convective overshooting is considered, but the flame would quench somewhere inside the WD, resulting in the formation of a C–O–Si WD. Owing to the inefficiency of thermohaline mixing, the C–O–Si WD may explode as an SN Ia if it continues to grow in mass. Our radiation transfer simulations show that SN ejecta with silicon-rich outer layers will form high-velocity absorption lines in Si ii, leading to some similarities to a class of high-velocity SNe Ia in spectral evolution. We estimate that the birthrate of SNe Ia with Si-rich envelopes is ∼$1\times 10^{-4}\, \mbox{yr}^{-1}$ in our Galaxy.

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