L. G. Althaus
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View article: Post-common envelope evolution of helium-core white dwarfs
Post-common envelope evolution of helium-core white dwarfs Open
Context. Helium-core white dwarfs (He WDs) from the common envelope (CE) channel offer insights into binary evolution and compact remnant formation. Their cooling rates influence their detectability and affect age estimates of close binari…
View article: Testing the mass-radius relation of white dwarfs in common proper-motion pairs
Testing the mass-radius relation of white dwarfs in common proper-motion pairs Open
Context. White dwarf masses are among the most important properties used to constrain their past and future evolution. Direct estimates of white dwarf masses are crucial for assessing the validity of theoretical evolutionary models and met…
View article: Testing the mass-radius relation of white dwarfs in common proper motion pairs I.Hydrogen-dominated atmospheres
Testing the mass-radius relation of white dwarfs in common proper motion pairs I.Hydrogen-dominated atmospheres Open
The main goal of this work was to measure the masses and radii of white dwarfs that belong to widely separated, common proper motion binaries with non-degenerate companions. These can be assessed, independently from theoretical mass-radius…
View article: A Second Candidate Magnetic Helium Core White Dwarf and 3 Other Variable White Dwarfs in the Globular Cluster NGC 6397
A Second Candidate Magnetic Helium Core White Dwarf and 3 Other Variable White Dwarfs in the Globular Cluster NGC 6397 Open
Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs (WDs; 0.18 M ⊙ ≤ M ≤ 0.5 M ⊙ ) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of 5.21 ±…
View article: Explorando el impacto de los gradientes químicos en los procesos de mezcla del interior estelar
Explorando el impacto de los gradientes químicos en los procesos de mezcla del interior estelar Open
During the various steps of stellar evolution are formed convectives zones that alter the chemical stratification in stars. Usually, in astrophysics is used the Mixing Length Theory (MLT) for modeling the convective movement and, in genera…
View article: J0526+5934: A peculiar ultra-short-period double white dwarf
J0526+5934: A peculiar ultra-short-period double white dwarf Open
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 merger episodes that …
View article: The Impact of Breathing Pulses during Core Helium Burning on the Core Chemical Structure and Pulsations of Hydrogen-rich Atmosphere White Dwarfs
The Impact of Breathing Pulses during Core Helium Burning on the Core Chemical Structure and Pulsations of Hydrogen-rich Atmosphere White Dwarfs Open
Breathing pulses are mixing episodes that could develop during the core helium-burning phase of low- and intermediate-mass stars. The occurrence of breathing pulses is expected to bear consequences on the formation and evolution of white d…
View article: The impact of breathing pulses during core-helium burning on the core chemical structure and pulsations of hydrogen-rich atmosphere white dwarfs
The impact of breathing pulses during core-helium burning on the core chemical structure and pulsations of hydrogen-rich atmosphere white dwarfs Open
Breathing pulses are mixing episodes that could develop during the core-helium burning phase of low- and intermediate-mass stars. The occurrence of breathing pulses is expected to bear consequences on the formation and evolution of white d…
View article: Asteroseismological analysis of the polluted ZZ Ceti star G 29 − 38 with <i>TESS</i>
Asteroseismological analysis of the polluted ZZ Ceti star G 29 − 38 with <i>TESS</i> Open
G 29 − 38 (TIC 422526868) is one of the brightest (V = 13.1) and closest (d = 17.51 pc) pulsating white dwarfs with a hydrogen-rich atmosphere (DAV/ZZ Ceti class). It was observed by the TESS spacecraft in sectors 42 and 56. The atmosphere…
View article: Asteroseismological analysis of the polluted ZZ Ceti star G29-38 with TESS
Asteroseismological analysis of the polluted ZZ Ceti star G29-38 with TESS Open
G\,29$-$38 (TIC~422526868) is one of the brightest ($V=13.1$) and closest ($d = 17.51$\,pc) pulsating white dwarfs with a hydrogen-rich atmosphere (DAV/ZZ Ceti class). It was observed by the {\sl TESS} spacecraft in sectors 42 and 56. The …
View article: General relativistic pulsations of ultra-massive ZZ Ceti stars
General relativistic pulsations of ultra-massive ZZ Ceti stars Open
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 explosions. It …
View article: General relativistic pulsations of ultra-massive ZZ Ceti stars
General relativistic pulsations of ultra-massive ZZ Ceti stars Open
Ultra-massive white dwarf stars are currently being discovered at a considerable rate, thanks to surveys such as the {\it Gaia} space mission. These dense and compact stellar remnants likely play a major role in type Ia supernova explosion…
View article: Carbon-oxygen ultra-massive white dwarfs in general relativity
Carbon-oxygen ultra-massive white dwarfs in general relativity Open
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 Msun that fully take into account the effects …
View article: Carbon–oxygen ultra-massive white dwarfs in general relativity
Carbon–oxygen ultra-massive white dwarfs in general relativity Open
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 the effects of…
View article: The “Canonical” White Dwarf Cooling Sequence of M5
The “Canonical” White Dwarf Cooling Sequence of M5 Open
Recently, slowly cooling white dwarfs (WDs) are a new class of WD that have been identified in two globular clusters (namely M13 and NGC 6752), showing a horizontal branch (HB) morphology with an extended blue tail. The cooling rate of the…
View article: A hidden population of white dwarfs with atmospheric carbon traces in the <i>Gaia</i> bifurcation
A hidden population of white dwarfs with atmospheric carbon traces in the <i>Gaia</i> bifurcation Open
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 A branch consists…
View article: A hidden population of white dwarfs with atmospheric carbon traces in the Gaia bifurcation
A hidden population of white dwarfs with atmospheric carbon traces in the Gaia bifurcation Open
The ESA Gaia space mission has revealed a bifurcation of the white dwarf (WD) sequence on the color magnitude diagram in two branches: A and B. While the A branch consists mostly of WDs with H-rich atmospheres, the B branch is not complete…
View article: The "canonical" White Dwarf Cooling Sequence of M5
The "canonical" White Dwarf Cooling Sequence of M5 Open
Recently, a new class of white dwarfs (dubbed ``slowly cooling WDs'') has been identified in two globular clusters (namely M13 and NGC 6752) showing a horizontal branch (HB) morphology with an extended blue tail. The cooling rate of these …
View article: WD J004917.14−252556.81: the most massive pulsating white dwarf
WD J004917.14−252556.81: the most massive pulsating white dwarf Open
We present Apache Point Observatory (APO) and Gemini time-series photometry of WD J004917.14−252556.81, an ultramassive DA white dwarf with $T_{\rm eff} = 13\, 020$ K and log g = 9.34. We detect variability at two significant frequencies, …
View article: Exploring the internal rotation of the extremely low-mass He-core white dwarf GD 278 with TESS asteroseismology
Exploring the internal rotation of the extremely low-mass He-core white dwarf GD 278 with TESS asteroseismology Open
Context. The advent of high-quality space-based photometry, brought about by missions such as Kepler /K2 and TESS, makes it possible to unveil the fundamental parameters and properties of the interiors of white dwarf stars, particularly ex…
View article: Exploring the internal rotation of the extremely low-mass He-core white dwarf GD 278 with TESS asteroseismology
Exploring the internal rotation of the extremely low-mass He-core white dwarf GD 278 with TESS asteroseismology Open
(Abridged) We present an exploration of the internal rotation of GD 278, the first pulsating extremely low-mass white dwarf that shows rotational splittings within its periodogram. We assess the theoretical frequency splittings expected fo…
View article: A candidate magnetic helium core white dwarf in the globular cluster NGC 6397
A candidate magnetic helium core white dwarf in the globular cluster NGC 6397 Open
We report a peculiar variable blue star in the globular cluster NGC 6397, using Hubble Space Telescope optical imaging. Its position in the colour-magnitude diagrams, and its spectrum, are consistent with this star being a helium core whit…
View article: Newtonian pulsations of relativistic ONe-core ultra-massive DA white dwarfs
Newtonian pulsations of relativistic ONe-core ultra-massive DA white dwarfs Open
Ultra-massive H-rich (DA spectral type) white dwarf stars ($M_{\star} > 1.05 M_{\odot}$) are expected to be substantially crystallized by the time they reach the ZZ Ceti instability strip ($T_{\rm eff} \sim 12\,000$ K). Crystallization lea…
View article: Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS Open
Context. The TESS space mission has recently demonstrated its great potential to discover new pulsating white dwarf and pre-white dwarf stars, and to detect periodicities with high precision in already known white-dwarf pulsators. Aims. We…
View article: Pulsating H-deficient WDs and pre-WDs observed with TESS: V. Discovery of two new DBV pulsators, WD J152738.4-450207.4 and WD 1708-871, and asteroseismology of the already known DBV stars PG 1351+489, EC 20058-5234, and EC 04207-4748
Pulsating H-deficient WDs and pre-WDs observed with TESS: V. Discovery of two new DBV pulsators, WD J152738.4-450207.4 and WD 1708-871, and asteroseismology of the already known DBV stars PG 1351+489, EC 20058-5234, and EC 04207-4748 Open
The {\sl TESS} space mission has recently demonstrated its great potential to discover new pulsating white dwarf and pre-white dwarf stars, and to detect periodicities with high precision in already known white-dwarf pulsators. We report t…
View article: Structure and evolution of ultra-massive white dwarfs in general relativity
Structure and evolution of ultra-massive white dwarfs in general relativity Open
Context. Ultra-massive white dwarfs ( M ⋆ ≳ 1.05 M ⊙ ) 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 i…
View article: Structure and evolution of ultra-massive white dwarfs in general relativity
Structure and evolution of ultra-massive white dwarfs in general relativity Open
We present the first set of constant rest-mass ultra-massive oxygen/neon white dwarf cooling tracks with masses larger than 1.29 Msun which fully take into account the effects of general relativity on their structural and evolutionary prop…
View article: Slowly Cooling White Dwarfs in NGC 6752
Slowly Cooling White Dwarfs in NGC 6752 Open
Recently, a new class of white dwarfs (“slowly cooling WDs”) has been identified in the globular cluster M13. The cooling time of these stars is increased by stable thermonuclear hydrogen burning in their residual envelope. These WDs are t…
View article: Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields?
Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields? Open
Ultra-massive white dwarfs ($1.05\, \rm M_\odot \lesssim M_{WD}$) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-mas…
View article: Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields?
Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields? Open
Ultra-massive white dwarfs ($ 1.05 \rm M_\odot \lesssim M_{WD}$) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-mass…