Browsing by Author "Althaus, Leandro G."

Now showing items 1-20 of 23

    • A hidden population of white dwarfs with atmospheric carbon traces in the Gaia bifurcation 

      Camisassa, María Eugenia; Torres Gil, Santiago; Hollands, Mark; Koester, Detlev; Raddi, Roberto; Althaus, Leandro G.; Rebassa Mansergas, Alberto (EDP Sciences, 2023-06-01)
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      Open Access
      Context. The high-quality photometric and astrometric capabilities of the ESA Gaia space mission have revealed a bifurcation of the white dwarf sequence on the color magnitude diagram with two branches: A and B. While the ...

    • An asteroseismic constraint on the mass of the axion from the period drift of the pulsating da white dwarf star L19-2 

      Córsico, Alejandro H.; Romero, Alejandra Daniela; Althaus, Leandro G.; García-Berro Montilla, Enrique; Isern Vilaboy, Jordi; Kepler, S.O.; Miller Bartolami, Marcelo M.; Sullivan, Denis J. (2016-07-01)
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      Open Access
      We employ an asteroseismic model of L19-2, a relatively massive (Msstarf ~ 0.75 M¿) and hot (Teff ~ 12 100 K) pulsating DA (H-rich atmosphere) white dwarf star (DAV or ZZ Ceti variable), and use the observed values of the ...

    • Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields? 

      Camisassa, María Eugenia; Raddi, Roberto; Althaus, Leandro G.; Isern Vilaboy, Jordi; Rebassa Mansergas, Alberto; Torres, Santiago; Córsico, Alejandro H.; Korre, Lydia (Oxford University Press, 2022-10-01)
      Article
      Open Access
      Ultra-massive white dwarfs (1.05M¿ . MWD) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-massive ...

    • Carbon-oxygen ultra-massive white dwarfs in general relativity 

      Althaus, Leandro G.; Corsico, Alejandro H.; Camisassa, María Eugenia; Torres Gil, Santiago; Gil Pons, Pilar; Rebassa Mansergas, Alberto; Raddi, Roberto (Oxford University Press, 2023-08-01)
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      Open Access
      We employ the La Plata stellar evolution code, lpcode, to compute the first set of constant rest-mass carbon–oxygen ultra-massive white dwarf evolutionary sequences for masses higher than 1.29 M¿ that fully take into account ...

    • Constraining the neutrino magnetic dipole moment from white dwarf pulsations 

      Corsico, Alejandro H.; Althaus, Leandro G.; Miller Bartolami, Marcelo M.; Kepler, S.O.; García-Berro Montilla, Enrique (2014-08-01)
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      Open Access
      Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models ...

    • Effects of Ne-22 sedimentation and metallicity on the local 40 pc white dwarf luminosity function 

      Tononi García, Jordi; Torres Gil, Santiago; García-Berro Montilla, Enrique; Camisassa, María E.; Althaus, Leandro G.; Rebassa Mansergas, Alberto (EDP Sciences, 2019-08-06)
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      Open Access
      We analyzed the effect of the sedimentation of 22Ne on the local white dwarf luminosity function by studying scenarios under different Galactic metallicity models. Methods. We use an advanced population synthesis code based ...

    • Forever young white dwarfs: When stellar ageing stops 

      Camisassa, María Eugenia; Althaus, Leandro G.; Torres Gil, Santiago; Córsico, Alejandro H.; Rebassa Mansergas, Alberto; Tremblay, P. E.; Cheng, Sihao; Raddi, Roberto (EDP Sciences, 2021-05-01)
      Article
      Open Access
      White dwarf stars are the most common end point of stellar evolution. The ultramassive white dwarfs are of special interest as they are related to type Ia supernovae explosions, merger events, and fast radio bursts. ...

    • Gaia DR2 white dwarfs in the Hercules stream 

      Torres Gil, Santiago; Cantero, Carles; Camisassa, María E.; Antoja, T.; Rebassa Mansergas, Alberto; Althaus, Leandro G.; Thelemaque, Thomas; Canovas Cabrera, Héctor (EDP Sciences, 2019-09-01)
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      Open Access
      We analyzed the velocity space of the thin- and thick-disk Gaia white dwarf population within 100 pc by searching for signatures of the Hercules stellar stream. We aimed to identify objects belonging to the Hercules stream, ...

    • General relativistic pulsations of ultra-massive ZZ Ceti stars 

      Córsico, Alejandro H.; Boston, Reece; Althaus, Leandro G.; Kilic, Mukremin; Kepler, Souza Oliveira; Camisassa, María Eugenia; Torres Gil, Santiago (Oxford University Press, 2023-10-01)
      Article
      Open Access
      Ultra-massive white dwarf stars are currently being discovered at a considerable rate, thanks to surveys such as the Gaia space mission. These dense and compact stellar remnants likely play a major role in Type Ia supernova ...

    • Is the central binary system of the planetary nebula Henize 2-428 a type Ia supernova progenitor? 

      García-Berro Montilla, Enrique; Soker, Noam; Althaus, Leandro G.; Ribas Canudas, Ignasi; Morales Peralta, Juan Carlos (2016-05-01)
      Article
      Open Access
      We critically discuss the recent observations of the binary system at the center of the bipolar planetary nebula Henize 2-428. We find that the proposed explanation of two equal-mass degenerate objects with a total mass ...

    • J0526+5934: A peculiar ultra-short-period double white dwarf 

      Rebassa Mansergas, Alberto; Hollands, Mark; Parsons, Steven G.; Althaus, Leandro G.; Pelisoli, Ingrid; Irawati, Puji; Raddi, Roberto; Camisassa, María Eugenia; Torres Gil, Santiago (EDP Sciences, 2024-06-13)
      Article
      Open Access
      Context. Ultra-short-period compact binaries are important sources of gravitational waves. The class of short-period compact binaries includes, for example, the progenitors of type Ia supernovae and the progenitors of ...

    • Revisiting the luminosity function of single halo white dwarfs 

      Cojocaru, Elena Ruxandra; Torres Gil, Santiago; Althaus, Leandro G.; Isern Vilaboy, Jordi; García-Berro Montilla, Enrique (EDP Sciences, 2015-09-01)
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      Open Access
      Context. White dwarfs are the fossils left by the evolution of low- and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the ...

    • Structure and evolution of ultra-massive white dwarfs in general relativity 

      Althaus, Leandro G.; Camisassa, María Eugenia; Torres Gil, Santiago; Battich, Tiara; Córsico, Alejandro H.; Rebassa Mansergas, Alberto; Raddi, Roberto (EDP Sciences, 2022-12-01)
      Article
      Open Access
      Ultra-massive white dwarfs (M? & 1.05M ) are of utmost importance in view of the role they play in type Ia supernovae explosions, merger events, the existence of high magnetic field white dwarfs, and the physical processes ...

    • The effect of 22Ne diffusion in the evolution and pulsational properties of white dwarfs with solar metallicity prgenitors 

      Camisassa, Maria E; Althaus, Leandro G.; Corsico, Alejandro H.; Vinyoles, Núria; Serenelli, Aldo M.; Isem, Jordi; Miller Bertolami, Marcelo M; García-Berro Montilla, Enrique (Institute of Physics (IOP), 2016-06-01)
      Article
      Open Access
      © 2016. The American Astronomical Society. All rights reserved. Because of the large neutron excess of 22Ne, sedimentation of this isotope occurs rapidly in the interior of white dwarfs. This process releases an additional ...

    • The evolution of ultra-massive carbon-oxygen white dwarfs 

      Camisassa, María Eugenia; Althaus, Leandro G.; Koester, Detlev; Torres, Santiago; Gil Pons, Pilar; Córsico, Alejandro H. (Oxford University Press, 2022-04-01)
      Article
      Open Access
      Ultra-massive white dwarfs (MWD¿1.05M¿) are considered powerful tools to study type Ia supernovae explosions, merger events, the occurrence of physical processes in the Super Asymptotic Giant Branch (SAGB) phase, and the ...

    • The evolution of white dwarfs resulting from helium-enhanced, low-metallicity progenitor stars 

      Althaus, Leandro G.; de Geronimo, Francisco; Córsico, Alejandro H.; Torres Gil, Santiago; García-Berro Montilla, Enrique (EDP Sciences, 2017-01-01)
      Article
      Open Access
      Context. Some globular clusters host multiple stellar populations with different chemical abundance patterns. This is particularly true for ¿ Centauri, which shows clear evidence of a helium-enriched subpopulation characterized ...

    • The formation of ultra-massive carbon-oxygen core white dwarfs and their evolutionary and pulsational properties 

      Althaus, Leandro G.; Gil Pons, Pilar; Córsico, Alejandro H.; Camisassa, María Eugenia; Miller Bertolami, Marcelo M; de Geronimo, Francisco; Torres Gil, Santiago; Gutiérrez Cabello, Jordi; Rebassa Mansergas, Alberto (EDP Sciences, 2021-02)
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      Open Access
      The existence of ultra-massive white dwarf stars, MWD & 1.05M , has been reported in several studies. These white dwarfs are relevant for the role they play in type Ia Supernova explosions, the occurrence of physical ...

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

      Córsico, Alejandro H.; Gil Pons, Pilar; Torres Gil, Santiago; Althaus, Leandro G. (EDP Sciences, 2021-02)
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      Open Access
      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 ...

    • The white dwarf cooling sequence of 47 Tucanae 

      García-Berro Montilla, Enrique; Torres Gil, Santiago; Althaus, Leandro G.; Miller Bartolami, Marcelo M. (2014-11)
      Article
      Open Access
      Context. 47 Tucanae is one of the most interesting, well-observed, and theoretically studied globular clusters. This allows us to determine the reliability of our understanding of white dwarf cooling sequences, to compare ...

    • The white dwarf population of NGC 6397 

      Torres Gil, Santiago; García-Berro Montilla, Enrique; Althaus, Leandro G.; Camisassa, Maria E (2015-09-01)
      Article
      Open Access
      Context. NGC 6397 is one of the most interesting, well-observed, and most thoroughly theoretically studied globular clusters. The existing wealth of observations allows us to study the reliability of the theoretical white ...