Slowly cooling white dwarfs in M13 from stable hydrogen burning

Chen, Jianxing; Ferraro, F. R.; Cadelano, Mario; Salaris, Maurizio; Lanzoni, B.; Pallanca, Cristina; Althaus, Leandro Gabriel; Dalessandro, E.

doi:10.1038/s41550-021-01445-6

Cited by 17 publications

(22 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, residual nuclear burning down to advanced evolutionary stages of WD evolution is allowed. The role played by residual H burning is not negligible (see Chen et al 2021, for recent observational evidence of quiescent thermonuclear activity occurring in cooling WDs) and by the time evolution reaches the ZZ Ceti domain, it has yielded a substantial reduction of the H content with which the WD enters its cooling branch.…”

Section: New Wd Evolutionary Modelsmentioning

confidence: 99%

New DA white dwarf models for asteroseismology of ZZ Ceti stars

Althaus

Córsico

2022

A&A

Self Cite

View full text Add to dashboard Cite

Context. Asteroseismology is a powerful tool used to infer the evolutionary status and chemical stratification of white dwarf stars and to gain insights into the physical processes that lead to their formation. This is particularly true for the variable hydrogen-rich atmosphere (DA) white dwarfs, known as DAV or ZZ Ceti stars. They constitute the most numerous class of pulsating white dwarfs. Aims. We present a new grid of white dwarf models that take into account advances made over the last decade in modeling and input physics of both the progenitor and the white dwarf stars. As a result, it is possible to avoid several shortcomings present in the set of white dwarf models employed in the asteroseismological analyses of ZZ Ceti stars that we carried out in our previous works. Methods. We generate white dwarf stellar models appropriate for ZZ Ceti stars with masses from ∼0.52 to ∼0.83 M⊙, resulting from the whole evolution of initially 1.5–4.0 M⊙ mass star models. These new models are derived from a self-consistent way with the changes in the internal chemical distribution that result from the mixing of all the core chemical components induced by mean molecular-weight inversions, from 22Ne diffusion, Coulomb sedimentation, and from residual nuclear burning. In addition, the expected nuclear-burning history and mixing events along the progenitor evolution are accounted for, in particular the occurrence of third dredge-up, which determines the properties of the core and envelope of post-AGB and white dwarf stars, as well as the white dwarf initial-final mass relation. The range of hydrogen envelopes of our new ZZ Ceti models extends from the maximum residual hydrogen content predicted by the progenitor history, log(MH/M⊙)∼ − 4 to −5, to log(MH/M⊙) = − 13.5, thus allowing for the first stellar models that would enable the search for seismological solutions for ZZ Ceti stars with extremely thin hydrogen envelopes – if, indeed, they do exist in nature. We computed the adiabatic gravity(g)-mode pulsation periods of these models. Calculations of our new evolutionary and pulsational ZZ Ceti models were performed with the LPCODE stellar evolution code and the LP-PUL stellar pulsation code. Results. Our new hydrogen-burning post-AGB models predict chemical structures for ZZ Ceti stars that are substantially different from those we used in our previous works, particularly in connection with the chemical profiles of oxygen and carbon near the stellar centre. We also discuss the implications of these new models for the pulsational spectrum of ZZ Ceti stars. Specifically, we find that the pulsation periods of g modes and the mode-trapping properties of the new models differ significantly from those characterizing the ZZ Ceti models of our previous works, particularly for long periods. Conclusions. The improvements in the modeling of ZZ Ceti stars we present here lead to substantial differences in the predicted pulsational properties of ZZ Ceti stars, which are expected to impact the asteroseismological inferences of these stars. This is extremely relevant in view of the abundant amount of photometric data from current and future space missions, resulting in discoveries of numerous ZZ Ceti stars.

show abstract

Section: New Wd Evolutionary Modelsmentioning

confidence: 99%

New DA white dwarf models for asteroseismology of ZZ Ceti stars

Althaus

Córsico

2022

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, unlike ω Cen, M13 is not known to host extreme He-rich stars that can form He-core WDs from single stellar evolution. Chen et al (2021) suggested that the bright WDs in M13 are the result of slow cooling due to the residual hydrogen burning on the C/O WD surface. Hence, it is possible that some of the FUV-detected WDs in ω Cen are such slowly cooling C/O WDs.…”

Section: Discussion and Summarymentioning

confidence: 99%

Globular Cluster UVIT Legacy Survey (GlobULeS). III. Omega Centauri in Far-ultraviolet

Prabhu

Subramaniam

Sahu

et al. 2022

ApJL

Self Cite

View full text Add to dashboard Cite

We present the first comprehensive study of the most massive globular cluster, Omega Centauri, in the far-ultraviolet (FUV), extending from the center to ∼28% of the tidal radius using the Ultraviolet Imaging Telescope on board AstroSat. A comparison of the FUV-optical color–magnitude diagrams with available canonical models reveals that horizontal branch (HB) stars bluer than the knee (hHBs) and the white dwarfs (WDs) are fainter in the FUV by ∼0.5 mag than model predictions. They are also fainter than their counterparts in M13, another massive cluster. We simulated HB with at least five subpopulations, including three He-rich populations with a substantial He enrichment of Y up to 0.43 dex, to reproduce the observed FUV distribution. We find the He-rich younger subpopulations to be radially more segregated than the He-normal older ones, suggesting an in situ enrichment from older generations. The ω Cen hHBs span the same T eff range as their M13 counterparts, but some have smaller radii and lower luminosities. This may suggest that a fraction of ω Cen hHBs are less massive than those of M13, similar to the result derived from earlier spectroscopic studies of outer extreme HB stars. The WDs in ω Cen and M13 have similar luminosity–radius–T eff parameters, and 0.44–0.46 M ⊙ He-core WD model tracks evolving from progenitors with Y = 0.4 dex are found to fit the majority of these. This study provides constraints on the formation models of ω Cen based on the estimated range in age, [Fe/H], and Y (in particular) for the HB stars.

show abstract

“…In searching for the optical companion to PSR J1835 −3259A and PSR J1835−3259B, we adopted the so-called "UV-route," a photometric procedure specifically optimized for the identification of blue and hot objects in crowded fields such as hot horizontal branch stars, blue straggler stars, and WDs and widely used by our group in previous papers (see Ferraro & Paresce 1993;Ferraro et al 1997aFerraro et al , 1997bFerraro et al , 2001aFerraro et al , 2003bDalessandro et al 2013b). Specifically, in this paper we followed the approach described in Cadelano et al (2019Cadelano et al ( , 2020; see also Raso et al 2017Raso et al , 2020Chen et al 2021Chen et al , 2022.…”

Section: Data Reductionmentioning

confidence: 99%

A Young White Dwarf Orbiting PSR J1835−3259B in the Bulge Globular Cluster NGC 6652

Chen

Cadelano

Pallanca

et al. 2023

ApJ

Self Cite

View full text Add to dashboard Cite

We report on the discovery of the companion star to the millisecond pulsar PSR J1835−3259B in the Galactic globular cluster NGC 6652. Taking advantage of deep photometric archival observations acquired through the Hubble Space Telescope in near-UV and optical bands, we identified a bright and blue object at a position compatible with that of the radio pulsar. The companion is located along the helium-core white dwarf cooling sequence, and the comparison with binary evolution models provides a mass of 0.17 ± 0.02 M ⊙, a surface temperature of 11,500 ± 1900 K, and a very young cooling age of only 200 ± 100 Myr. The mass and the age of the companion are compatible with a progenitor star of about 0.87 M ⊙, which started transferring mass to the primary during its evolution along the subgiant branch and stopped during the early red giant branch phase. Combining together the pulsar mass function and the companion mass, we found that this system is observed at an almost edge-on orbit and hosts a neutron star with a mass of 1.44 ± 0.06 M ⊙, thus suggesting a highly nonconservative mass accretion phase. The young age of the WD companion is consistent with the scenario of a powerful, relatively young MSP indicated by the earlier detection of gamma-rays from this system.

show abstract

Slowly cooling white dwarfs in M13 from stable hydrogen burning

Cited by 17 publications

References 47 publications

New DA white dwarf models for asteroseismology of ZZ Ceti stars

New DA white dwarf models for asteroseismology of ZZ Ceti stars

Globular Cluster UVIT Legacy Survey (GlobULeS). III. Omega Centauri in Far-ultraviolet

A Young White Dwarf Orbiting PSR J1835−3259B in the Bulge Globular Cluster NGC 6652

Contact Info

Product

Resources

About