Discovery of a hot ultramassive rapidly rotating DBA white dwarf

Пширков, М. С.; Dodin, A. V.; Belinski, A. A.; Желтоухов, С. Г.; Fedoteva, A. A.; Voziakova, O.; Potanin, S.; Блинников, С. И.; Постнов, К. А.

doi:10.1093/mnrasl/slaa149

Cited by 42 publications

(38 citation statements)

References 39 publications

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“…The downward triangles mark when 10 % of the mass is solid while the upward triangles mark when 90% of the mass is solid. The large star shows ZTF J190132.9+145808.7 (Caiazzo et al 2021) and the small star shows WD J183202.83+085636.24 (Pshirkov et al 2020).…”

Section: Resultsmentioning

confidence: 99%

“…As our sample of nearby WDs becomes increasing complete, thanks in large part to Gaia (Gaia Collaboration et al 2018;Gentile Fusillo et al 2019), a significant number of white dwarfs with masses 1.3 M are being revealed and better described. These include longstudied objects like GD 50 (Bergeron et al 1991;Gagné et al 2018) and RE J0317-853 (Barstow et al 1995;Ferrario et al 1997;Külebi et al 2010) as well more recently characterized objects like WD J183202.83+085636.24 (Pshirkov et al 2020) and ZTF J190132.9+145808.7 (Caiazzo et al 2021). In their analysis of the 100 pc sample from the Montreal White Dwarf Database, Kilic et al (2021) identify 25 WDs with masses > 1.3 M (assuming H atmospheres and C/O cores).…”

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confidence: 99%

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Cooling Models for the Most Massive White Dwarfs

Schwab

2021

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We present a set of ultramassive white dwarf models, focused on masses above 1.3 M . Given the uncertainties about the formation and compositions of such objects, we construct parameterized model sequences, guided by evolutionary calculations including both single star and double white dwarf merger formation channels. We demonstrate that the cooling of objects with central densities in excess of 10 9 g cm −3 is dominated by neutrino cooling via the Urca process in the first ≈ 100 Myr after formation. Our models indicate that the recently discovered ultramassive white dwarf ZTF J190132.9+145808.7 is likely to have experienced this Urca-dominated cooling regime. We also show that the high densities imply that diffusion is unlikely to significantly alter the core compositions of these objects before they crystallize.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Cooling Models for the Most Massive White Dwarfs

Schwab

2021

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“…Ultra-massive H-deficient WDs are less frequent than H-rich objects, but at least a handful of them have been detected in the SDSS (Kleinman et al 2013;Reindl et al 2014;Koester et al 2020;Bédard et al 2020). In addition, an ultra-massive DB WD with an effective temperature well within the DBV instability strip has been detected by Richer et al (2019) in a young open cluster, and a hot rapidly rotating DBA WD with a stellar mass of 1.33 M has been discovered by Pshirkov et al (2020). By means of the analysis of the period-spacing and mode-trapping features, we have shown that the pulsational properties of the ultra-massive DB WDs are much more strongly dependent on their formation scenario than in the case of the DA WD ones studied in Althaus et al (2021).…”

Section: Discussionmentioning

confidence: 99%

“…Its effective temperature, which is in excess of 25 000 K, places this ultra-massive DB WD inside the DBV instability strip. Recently, Pshirkov et al (2020) discovered an ultra-massive WD with He-rich atmosphere and traces of H (DBA spectral class) with T eff = 31 200 ± 1200 K and M = 1.33 M exhibiting photometric variability with a single period of 353.456 s, which could be due to fast rotation, supporting a merger scenario for its formation. However, it cannot be completely ruled out that the variability is due to pulsations since it is close to the blue edge of the DBV instability strip.…”

Section: Introductionmentioning

confidence: 96%

The pulsational properties of ultra-massive DB white dwarfs with carbon-oxygen cores coming from single-star evolution

Córsico

Althaus

Gil‐Pons

et al. 2021

A&A

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Context. Ultra-massive white dwarfs are relevant for many reasons: their role as type Ia supernova progenitors, the occurrence of physical processes in the asymptotic giant branch phase, the existence of high-field magnetic white dwarfs, and the occurrence of double white dwarf mergers. Some hydrogen-rich ultra-massive white dwarfs are pulsating stars and, as such, they offer the possibility of studying their interiors through asteroseismology. On the other hand, pulsating helium-rich ultra-massive white dwarfs could be even more attractive objects for asteroseismology if they were found, as they should be hotter and less crystallized than pulsating hydrogen-rich white dwarfs, something that would pave the way for probing their deep interiors. Aims. We explore the pulsational properties of ultra-massive helium-rich white dwarfs with carbon-oxygen and oxygen-neon cores resulting from single stellar evolution. Our goal is to provide a theoretical basis that could eventually help to discern the core composition of ultra-massive white dwarfs and the scenario of their formation through asteroseismology, anticipating the possible future detection of pulsations in helium-rich ultra-massive white dwarfs. Methods. We focus on three scenarios for the formation of helium-rich ultra-massive white dwarfs. First, we consider stellar models coming from two recently proposed single-star evolution scenarios for the formation of ultra-massive white dwarfs with carbon-oxygen cores that involve the rotation of the degenerate core after core helium burning and reduced mass-loss rates in massive asymptotic giant branch stars. Finally, we contemplate ultra-massive oxygen-neon core white-dwarf models resulting from standard single-star evolution. We compute the adiabatic pulsation gravity-mode periods for models in a range of effective temperatures, embracing the instability strip of average-mass pulsating helium-rich white dwarfs, and we compare the characteristics of the mode-trapping properties for models of different formation scenarios through the analysis of the period spacing. Results. Given that the white dwarf models coming from the three scenarios considered are characterized by distinct core chemical profiles, we find that their pulsation properties are also different, thus leading to distinctive signatures in the period-spacing and mode-trapping properties. Conclusions. Our results indicate that in the case of an eventual detection of pulsating ultra-massive helium-rich white dwarfs, it would be possible to derive valuable information encrypted in the core of these stars in connection with the origin of such exotic objects. This is of the utmost importance regarding recent evidence for the existence of a population of ultra-massive white dwarfs with carbon-oxygen cores. There will soon be many opportunities to detect pulsations in these stars through observations collected with ongoing space missions.

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“…Advanced LIGO and the Einstein Tele-scope. If applying this GW emission model to a rotating WD and unless the quadrupole moments of WDs are much larger than ∼ 10 40 g cm 2 , we will get a much smaller GW amplitude 10 −30 because WDs have rotation periods 300 s (Pshirkov et al 2020;Reding et al 2020;Kawaler 2015;Kissin & Thompson 2015).…”

Section: Namementioning

confidence: 99%

Orbital Evolution of Neutron-Star -- White-Dwarf Binaries by Roche-Lobe Overflow and Gravitational Wave Radiation

Yu,

Lu,

Jeffery

2021

Preprint

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We investigate the effects of mass transfer and gravitational wave (GW) radiation on the orbital evolution of contact neutron-star-white-dwarf (NS-WD) binaries, and the detectability of these binaries by space GW detectors (e.g., Laser Interferometer Space Antenna, LISA; Taiji; Tianqin). A NS-WD binary becomes contact when the WD component fills its Roche lobe, at which the GW frequency ranges from ∼ 0.0023 to 0.72 Hz for WD with masses ∼ 0.05 − 1.4M ⊙ . We find that some high-mass NS-WD binaries may undergo direct coalescence after unstable mass transfer. However, the majority of NS-WD binaries can avoid direct coalescence because mass transfer after contact can lead to a reversal of the orbital evolution. Our model can well interpret the orbital evolution of the ultra-compact X-ray source 4U 1820-30. For a 4-year observation of 4U 1820-30, the expected signal-to-noise-ratio (SNR) in GW characteristic strain is ∼ 11.0/10.4/2.2 (LISA/Taiji/Tianqin). The evolution of GW frequencies of NS-WD binaries depends on the WD masses. NS-WD binaries with masses larger than 4U 1820-30 are expected to be detected with significantly larger SNRs. For a (1.4 + 0.5)M ⊙ NS-WD binary close to contact, the expected SNR for a one week observation is ∼ 27/40/28 (LISA/Taiji/Tianqin). For NS-WD binaries with masses of (1.4+1.1)M ⊙ , the significant change of GW frequencies and amplitudes can be measured, and thus it is possible to determine the binary evolution stage. At distances up to the edge of the Galaxy (∼ 100 kpc), high-mass NS-WD binaries will be still detectable with SNR 1.

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Discovery of a hot ultramassive rapidly rotating DBA white dwarf

Cited by 42 publications

References 39 publications

Cooling Models for the Most Massive White Dwarfs

Cooling Models for the Most Massive White Dwarfs

The pulsational properties of ultra-massive DB white dwarfs with carbon-oxygen cores coming from single-star evolution

Orbital Evolution of Neutron-Star -- White-Dwarf Binaries by Roche-Lobe Overflow and Gravitational Wave Radiation

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