A hot subdwarf–white dwarf super-Chandrasekhar candidate supernova Ia progenitor

Pelisoli, Ingrid; Neunteufel, P.; Geier, S.; Kupfer, Thomas; Heber, U.; Irrgang, A.; Schneider, D. P.; Bastian, A.; Roestel, Jan van; Schaffenroth, V.; Barlow, B. N.

doi:10.1038/s41550-021-01413-0

Cited by 52 publications

(40 citation statements)

References 101 publications

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“…Varying the assumed systemic velocity by ±10 km/s and the canonical hot subdwarf mass by ±0.1 M alters the estimated companion mass by ∼ 0.05 M and ∼ 0.1 M respectively. Pelisoli et al (2021) find HD 265435 to be a supernova Ia progenitor and AQ Col could be similar. Further AQ Col radial velocity observations are needed to confirm that this wide binary has a hot subdwarf which itself is a close binary whose components have a combined mass that exceeds the Chandrasekhar-Mass.…”

Section: Discussionmentioning

confidence: 80%

Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

Otani,

Lynas-Gray,

Kilkenny

et al. 2021

Preprint

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AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. However, its periodic pulsation timing variations indicate that AQ Col may not be a single star. We present pulsation period variations observed over twenty-four years and derived orbital characteristics these would imply if these were a consequence of AQ Col being a pulsating hot subdwarf in a long-period binary. The derived orbital period is P = 486.0 days. In the sdB star binary evolution scenario, a Roche lobe overflow channel results in long period (450 ≤ P ≤ 1400 d) for sdB + Main Sequence (MS) binaries. However the derived orbital eccentricity of the system is 0.424, which is too large for a typical long period sdB+MS system. The Skymapper u -z vs. z -WISE W1 diagram is incompatible with sdB+MS binary systems, and suggests the system contains a white dwarf or other hot and faint object. The expected radial velocity amplitude of AQ Col due to this orbital motion is ∼15 km/s. However, the radial velocity amplitude differences obtained from spectroscopy show that the amplitude could be more than ∼ 300 km/s, which indicates the possibility that AQ Col also has a short period companion with orbital period of ∼ 1 day. Therefore, the AQ Col system may be a triple star system. Because such systems have not yet been studied in detail, AQ Col may offer unique insight into the production of sdB stars and this system deserves continued time-series and spectroscopic monitoring.

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Section: Discussionmentioning

confidence: 80%

Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

Otani,

Lynas-Gray,

Kilkenny

et al. 2021

Preprint

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“…Pakmor et al (2021) have also proposed yet another possibility for producing runaways with velocities up to 1000-1500 km s −1 from binaries containing a massive He-C/O WD (e.g. Zenati et al 2019;Pelisoli et al 2021) donating material onto a C/O WD companion. In that case, the donor's thick He envelope may experience a detonation and release the accretor WD as a hypervelocity runaway.…”

Section: Discussionmentioning

confidence: 99%

Masses of White Dwarf Binary Companions to Type Ia Supernovae Measured from Runaway Velocities

Bauer,

Chandra,

Shen

et al. 2021

Preprint

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The recently proposed "dynamically driven double-degenerate double-detonation" (D 6 ) scenario posits that Type Ia supernovae (SNe) may occur during dynamically unstable mass transfer between two white dwarfs (WDs) in a binary. This scenario predicts that the donor WD may then survive the explosion and be released as a hypervelocity runaway, opening up the exciting possibility of identifying remnant stars from D 6 SNe and using them to study the physics of detonations that produce Type Ia SNe. Three candidate D 6 runaway objects have been identified in Gaia data. The observable runaway velocity of these remnant objects represents their orbital speed at the time of SN detonation. The orbital dynamics and Roche lobe geometry required in the D 6 scenario place specific constraints on the radius and mass of the donor WD that becomes the hypervelocity runaway. In this letter, we calculate the radii required for D 6 donor WDs as a function of the runaway velocity. Using mass-radius relations for WDs, we then constrain the masses of the donor stars as well. With measured velocities for each of the three D 6 candidate objects based on Gaia EDR3, this work provides a new probe of the masses and mass ratios in WD binary systems that produce SN detonations and hypervelocity runaways.

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“…;Kupfer et al , 2017bKupfer et al , 2022Schaffenroth et al 2018Schaffenroth et al , 2021Vennes et al 2018;Bell et el. 2019;Ratzloff et al 2019Ratzloff et al , 2020Löbling 2020;Reindl et al 2020;Pelisoli et al 2021;Pawar et al priv. comm.…”

Section: Helium Abundanceunclassified

Radial velocity variability and evolution of hot subdwarf stars

Geier,

Dorsch,

Pelisoli

et al. 2022

Preprint

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Hot subdwarf stars represent a late and peculiar stage in the evolution of low-mass stars, because they are likely formed by close binary interactions. Here we performed a radial velocity (RV) variability study of a sample of 646 hot subdwarfs with multi-epoch radial velocities from Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra. Atmospheric parameters and RVs were taken from the literature. For stars with archival spectra but without literature values, we determined the parameters by fitting model atmospheres. In addition, we redetermined the atmospheric parameters and RVs for all the He-enriched sdO/Bs. This large sample allowed us to study RV-variability as a function of the location in the T eff − log gand T eff − log n(He)/n(H) diagrams in a statistically significant way. As diagnostics we used the fraction of RV-variable stars and the distribution of the maximum RV variations ∆RV max . Both indicators turned out to be quite inhomogeneous across the studied parameter ranges. A striking feature is the completely different behaviour of He-poor and He-rich hot subdwarfs. While the former have a high fraction of close binaries, almost no significant RV variations could be detected for the latter. This led us to the conclusion that there likely is no evolutionary connection between these subtypes. Intermediate He-rich-and extreme He-rich sdOB/Os on the other hand are likely related. We conclude further that the vast majority of this population is formed via one or several binary merger channels. Hot subdwarfs with temperatures cooler than ∼ 24 000 K tend to show less and smaller RV-variations. These objects might constitute a new subpopulation of binaries with longer periods and late-type or compact companions. The RV-variability properties of the extreme horizontal branch (EHB) and corresponding post-EHB populations of the He-poor hot subdwarfs match and confirm the predicted evolutionary connection between them. Stars found below the canonical EHB at somewhat higher surface gravities show large RV-variations and a high RV-variability fraction, which is consistent with most of them being low-mass EHB stars or progenitors of low-mass helium white dwarfs in close binaries.

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A hot subdwarf–white dwarf super-Chandrasekhar candidate supernova Ia progenitor

Cited by 52 publications

References 101 publications

Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

Masses of White Dwarf Binary Companions to Type Ia Supernovae Measured from Runaway Velocities

Radial velocity variability and evolution of hot subdwarf stars

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