Discovery and characterization of five new eclipsing AM CVn systems

van Roestel, J.; Kupfer, T.; Green, M. J.; Wong, S.; Bildsten, L.; Burdge, K.; Prince, T.; Marsh, T. R.; Szkody, P.; Fremling, C.; Graham, M. J.; Dhillon, V. S.; Littlefair, S. P.; Bellm, E. C.; Coughlin, M.; Duev, D. A.; Goldstein, D. A.; Laher, R. R.; Rusholme, B.; Riddle, R.; Dekany, R.; Kulkarni, S. R.

doi:10.48550/arxiv.2107.07573

Cited by 3 publications

(4 citation statements)

References 70 publications

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“…Finally, isolated WDs show evidence of a cooling delay (e.g., Cheng et al 2019;Kilic et al 2020), and we speculate that a similar phenomenon in the accretor may well explain the observed discrepancy. The recent discovery of 5 new eclipsing AM CVn systems with P orb = 35 − 62 min by van Roestel et al (2021), which constrains the luminosity contributions from different components and the degree of cooling of the donor, will help disentangle these various scenarios.…”

Section: Discussionmentioning

confidence: 99%

“…Our nuclear net includes the NCO reaction chain (Bauer et al 2017) which may impact the helium shell thickness for unstable burning on the accretor. The models presented in this work differ slightly from an earlier version of models presented in van Roestel et al (2021). The latter adopted the HELM EOS (Timmes & Swesty 2000) during the early phases of mass transfer for the He WD donor, and included no electron conduction opacity correction from Blouin et al (2020) for both WDs.…”

Section: Computational Setup and Initial Stellar Model Constructionmentioning

confidence: 99%

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Inlists and Output files for paper: Mass Transfer and Stellar Evolution of the White Dwarfs in AM CVn Binaries

Wong,

Bildsten

2021

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We calculate the stellar evolution of both white dwarfs (WDs) in AM CVn binaries with orbital periods of P orb ≈ 5 − 70 minutes. We focus on the cases where the donor starts as a M He < 0.2 M Helium WD and the accretor is a M WD > 0.6 M WD. Using Modules for Experiments in Stellar Astrophysics (MESA), we simultaneously evolve both WDs assuming conservative mass transfer and angular momentum loss from gravitational radiation. This self-consistent evolution yields the important feedback of the properties of the donor on the mass transfer rate, Ṁ , as well as the thermal evolution of the accreting WD. Consistent with earlier work, we find that the high Ṁ 's at early times forces an adiabatic evolution of the donor for P orb < 30 minutes so that its mass-radius relation depends primarily on its initial entropy. As the donor reaches M He ≈ 0.02 − 0.03 M at P orb 30 minutes, it becomes fully convective and could lose entropy and expand much less than expected under further mass loss. However, we show that the lack of reliable opacities for the donor's surface inhibit a secure prediction for this possible cooling. Our calculations capture the core heating that occurs during the first ≈ 10 7 years of accretion and continue the evolution into the phase of WD cooling that follows. When compared to existing data for accreting WDs, as seen by Cheng and collaborators for isolated WDs, we also find that the accreting WDs are not as cool as we would expect given the amount of time they have had to cool.

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Section: Discussionmentioning

confidence: 99%

Section: Computational Setup and Initial Stellar Model Constructionmentioning

confidence: 99%

Inlists and Output files for paper: Mass Transfer and Stellar Evolution of the White Dwarfs in AM CVn Binaries

Wong,

Bildsten

2021

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“…However, during the subsequent GW damping of the system, the more extended ELM He WD component will fill its Roche lobe and initiate RLO towards the CO WD companion. During this epoch, the system will be observable as an AM CVn system (Nelemans et al 2001;van Roestel et al 2021). Discussions and detailed tracks of their evolution through the LISA GW frequency band during this phase is given in e.g.…”

Section: A Lisa Verification Sourcementioning

confidence: 99%

Formation of the double white dwarf binary PTF J0533+0209 through stable mass transfer?

Chen¹,

Tauris²,

Chen³

et al. 2021

Preprint

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Double white dwarf (DWD) binaries are important for studies of common-envelope (CE) evolution, Type Ia supernova progenitors and Galactic sources of low-frequency gravitational waves (GWs). PTF J0533+0209 is a DWD system with a short orbital period of P orb ∼ 20 min and thus a so-called LISA verification source. The formation of this system and other DWDs is still under debate. In this paper, we discuss the possible formation scenarios of this binary and argue that it is not likely to have formed through CE evolution. Applying a new magnetic braking prescription, we use the MESA code to model the formation of this system through stable mass transfer. We find a model which can well reproduce the observed WD masses and orbital period but not the effective temperature and hydrogen abundance of the low-mass He WD component. We discuss the possibility of using H flashes to mitigate this discrepancy. Finally, we discuss the future evolution of this system into a AM CVn binary such as those that will be detected by space-borne GW observatories like LISA, TianQin and Taiji.

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“…HiPERCAM saw first light on the GTC in February 2018, and it has since been in use for 13 observing runs totalling ∼70 nights (although some of these nights were shared with other instruments or partly lost due to weather). The first tranche of scientific papers based on HiPERCAM data have now been published (Rebassa-Mansergas et al 2019, Nieder et al 2019, Paice et al 2019, Parsons et al 2020, Kupfer et al 2020a, Paice et al 2021, Burdge et al 2020, Kupfer et al 2020b, Montes et al 2021, van Roestel et al 2021. In this section, we summarise the performance of HiPERCAM on the GTC.…”

Section: Performance On the Gtcmentioning

confidence: 99%

HiPERCAM: a quintuple-beam, high-speed optical imager on the 10.4-m Gran Telescopio Canarias

Dhillon,

Bezawada,

Black

et al. 2021

Preprint

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HiPERCAM is a portable, quintuple-beam optical imager that saw first light on the 10.4-m Gran Telescopio Canarias (GTC) in 2018. The instrument uses re-imaging optics and 4 dichroic beamsplitters to record u s g s r s i s z s (320 − 1060 nm) images simultaneously on its five CCD cameras, each of 3.1 arcmin (diagonal) field of view. The detectors in HiPERCAM are frame-transfer devices cooled thermo-electrically to 183 K, thereby allowing both long-exposure, deep imaging of faint targets, as well as high-speed (over 1000 windowed frames per second) imaging of rapidly varying targets. A comparison-star pick-off system in the telescope focal plane increases the effective field of view to 6.7 arcmin for differential photometry. Combining HiPERCAM with the world's largest optical telescope enables the detection of astronomical sources to g s ∼ 23 in 1 s and g s ∼ 28 in 1 h. In this paper we describe the scientific motivation behind HiPERCAM, present its design, report on its measured performance, and outline some planned enhancements.

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Discovery and characterization of five new eclipsing AM CVn systems

Cited by 3 publications

References 70 publications

Inlists and Output files for paper: Mass Transfer and Stellar Evolution of the White Dwarfs in AM CVn Binaries

Inlists and Output files for paper: Mass Transfer and Stellar Evolution of the White Dwarfs in AM CVn Binaries

Formation of the double white dwarf binary PTF J0533+0209 through stable mass transfer?

HiPERCAM: a quintuple-beam, high-speed optical imager on the 10.4-m Gran Telescopio Canarias

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