Core crystallization and pile-up in the cooling sequence of evolving white dwarfs

Tremblay, Pier-Emmanuel; Fontaine, G.; Fusillo, N. P. Gentile; Dunlap, B. H.; Gänsicke, B. T.; Hollands, Mark; Hermes, J. J.; Marsh, T. R.; Cukanovaite, E.; Cunningham, Tim

doi:10.1038/s41586-018-0791-x

Cited by 152 publications

(165 citation statements)

References 28 publications

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“…Also, WDs are found in binary systems, thus offering a test bed to explore complex stellar interactions amongst stars, including WDs exploding as type Ia supernovae (Maoz et al, 2014). In addition, WDs can be used as cosmic laboratories of extreme physics, ranging from atomic and molecular physics in strong magnetic fields, and high-density plasmas and even solid-state physics (through crystallization; Winget et al, 2009;Tremblay et al, 2019), to exotic physics, like constraining the axion mass and the possible variation of the gravitational constant (Isern et al, 1992;Córsico et al, 2012bCórsico et al, , 2013, and also variations of the fine-structure constant (Hu et al, 2019). Last but not least, fundamental properties of WDs, either individually or collectively, like the mass distribution, core chemical composition, and cooling times are key to place constraints on the stellar evolution theory, including third dredge up and mass loss on the Asymptotic Giant Branch (AGB), the efficiency of extra-mixing during core helium burning, and nuclear reaction rates (Kunz et al, 2002;Salaris et al, 2009;Fields et al, 2016).…”

mentioning

confidence: 99%

Pulsating white dwarfs: new insights

Córsico

Althaus

Bertolami

et al. 2019

Astron Astrophys Rev

205

224

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Stars are extremely important astronomical objects that constitute the pillars on which the Universe is built, and as such, their study has gained increasing interest over the years. White dwarf stars are not the exception. Indeed, these stars constitute the final evolutionary stage for more than 95 per cent of all stars. The Galactic population of white dwarfs conveys a wealth of information about several fundamental issues and are of vital importance to study the structure, evolution and chemical enrichment of our Galaxy and its components -including the star formation history of the Milky Way. Several important studies have emphasized the advantage of using white dwarfs as reliable clocks to date a variety of stellar populations in the solar neighborhood and in the nearest stellar clusters, including the thin and thick disks, the Galactic spheroid and the system of globular and open clusters. In addition, white dwarfs are tracers of the evolution of planetary systems along several phases of stellar evolution. Not less relevant than these applications, the study of matter at high densities has benefited from our detailed knowledge about evolutionary and observational properties of white dwarfs. In this sense, white dwarfs are used as laboratories for astro-particle physics, being their interest focused on physics beyond the standard model, that is, neutrino physics, axion physics and also radiation from "extra dimensions", and even crystallization.The last decade has witnessed a great progress in the study of white dwarfs. In particular, a wealth of information of these stars from different surveys has

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mentioning

confidence: 99%

Pulsating white dwarfs: new insights

Córsico

Althaus

Bertolami

et al. 2019

Astron Astrophys Rev

205

224

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“…Even relatively old research fields like stellar structure and evolution received a boost from Gaia: given the extremely large statistics and high precision of the of Gaia DR2 photometry, a new feature in the CMD of the galaxy was found (Jao et al, 2018), i.e., a gap along the main sequence that was predicted theoretically but never confirmed observationally 13 , caused by the transition of M stars from the fully convective to the partially convective regime. Similarly, the sequence of white dwarfs, now very populous in the Gaia DR2 data, showed for the first time its detailed substructure, not only the double sequence traced by different types of white dwarfs, but also the piling-up of white dwarfs towards the bottom of the cooling sequence, seen in Gaia data for the first time, and likely caused by internal processes of crystallization (Tremblay et al, 2019).…”

Section: The Second Gaia Data Releasementioning

confidence: 64%

Gaia: The Galaxy in six (and more) dimensions

Pancino¹

2020

Advances in Space Research

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The ESA cornerstone mission Gaia was successfully launched in 2013, and is now scanning the sky to accurately measure the positions and motions of about two billion point-like sources of 3 V 20.5 mag, with the main goal of reconstructing the 6D phase space structure of the Milky Way. The typical uncertainties in the astrometry will be in the range 30-500 µas. The sky will be repeatedly scanned (70 times on average) for five years or more, adding the time dimension, and the Gaia data are complemented by mmag photometry in three broad bands, plus line-of-sight velocities from medium resolution spectroscopy for brighter stars. This impressive dataset is having a large impact on various areas of astrophysics, from solar system objects to distant quasars, from nearby stars to unresolved galaxies, from binaries and extrasolar planets to light bending experiments. This invited review paper presents an overview of the Gaia mission and describes why, to reach the goal performances in astrometry and to adequately map the Milky Way kinematics, Gaia was also equipped with state-of-the-art photometers and spectrographs, enabling us to explore much more than the 6D phase-space of positions and velocities. Scientific highlights of the first two Gaia data releases are briefly presented.

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“…Gaia photometry and parallax measurements have revealed a pile-up of high-mass WDs (Gaia Collaboration, et al 2018a) on the Hertzsprung-Russell diagram which has been labelled the Q branch. This has been interpreted by Tremblay et al (2019) as evidence of WD's crystallization whose onset delays cooling and causes this pile-up. However, Cheng et al (2019) have shown that the Q branch stars, of which half are DQs, have significantly older kinematics and therefore require an additional cooling delay of 8 Gyr to explain the pile-up which is most likely caused by the settling of 22 Ne.…”

Section: The Progenitor Stars Of Lp 93-21mentioning

confidence: 97%

An ancient double degenerate merger in the Milky Way halo

Kawka

Vennes

Ferrario

2019

Monthly Notices of the Royal Astronomical Society: Letters

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We present an analysis and re-appraisal of the massive, carbon-enriched (DQ) white dwarf (WD) LP 93-21. Its high mass (≈ 1 M ) and membership to the class of warm DQ WDs, combined with its peculiar halo kinematics suggest that this object is the product of an ancient stellar merger event, most likely that of two WDs. Furthermore, the kinematics places this object on a highly retrograde orbit driven by the accretion of a dwarf galaxy onto the Milky Way that occurred at a red shift greater than 1.5. As the product of a stellar merger LP 93-21 is probably representative of the whole class of warm/hot DQ WDs.

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Core crystallization and pile-up in the cooling sequence of evolving white dwarfs

Cited by 152 publications

References 28 publications

Pulsating white dwarfs: new insights

Pulsating white dwarfs: new insights

Gaia: The Galaxy in six (and more) dimensions

An ancient double degenerate merger in the Milky Way halo

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