Pulsation in the white dwarf HE 1017−1352: confirmation of the class of hot DAV stars

Romero, A. D.; Amaral, Larissa Antunes; Kurtz, D. W.; Shibahashi, Hiromoto

doi:10.1093/mnrasl/slaa106

Cited by 6 publications

(6 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Shibahashi (2005) predicted their existence, following which three cases were found (Kurtz et al 2013;Kurtz et al 2008). Some uncertainty whether these stars constitute a new class of pulsating white dwarfs persists, but the recent discovery of a fourth such star, HE 1017-1352, by Romero et al (2020) strengthens the case. For the latter star there are TESS data for which the pulsation signal, while not at the 1/1000 level of False Alarm probability, is consistent with the robust detections from ground-based photometry.…”

Section: B7 Dqv Hot Dav and Ultra-massive Dav Starsmentioning

confidence: 97%

Asteroseismology across the HR diagram

Kurtz¹

2022

Preprint

View full text Add to dashboard Cite

Asteroseismology has grown from its beginnings three decades ago to a mature field teeming with discoveries and applications. This phenomenal growth has been enabled by space photometry with precision 10 − 100 times better than ground-based observations, with nearly continuous light curves for durations of weeks to years, and by large scale ground-based surveys spanning years designed to detect all timevariable phenomena. The new high precision data are full of surprises, deepening our understanding of the physics of stars.• This review explores asteroseismic developments from the last decade primarily as a result of light curves from the Kepler and TESS space missions for: massive upper main-sequence OBAF stars, pre-mainsequence stars, peculiar stars, classical pulsators, white dwarfs and subdwarfs, and tidally interacting close binaries. • The space missions have increased the numbers of pulsators in many classes by an order of magnitude. • Asteroseismology measures fundamental stellar parameters and stellar interior physics -mass, radius, age, metallicity, luminosity, distance, magnetic fields, interior rotation, angular momentum transfer, convective overshoot, core burning stage -supporting disparate fields such as galactic archeology, exoplanet host stars, supernovae progenitors, gamma ray and gravitational wave precursors, close binary star origins and evolution, and standard candles. • Stars are the luminous tracers of the universe. Asteroseismology significantly improves models of stellar structure and evolution on which all inference from stars depends.

show abstract

Section: B7 Dqv Hot Dav and Ultra-massive Dav Starsmentioning

confidence: 97%

Asteroseismology across the HR diagram

Kurtz¹

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…This procedure is repeated N/2 times, where N is the number of points in the light curve. For each run, we compute the maximum amplitude of the FT. From the distribution of maxima, we take the 0.999 percentile as the detection limit (Romero et al 2020). The internal uncertainties in frequency and amplitude were computed using a Monte Carlo method with 100 simulations with PERIOD04, while uncertainties in the periods were obtained through error propagation.…”

Section: Light Curve Analysis: Looking For Periodicitiesmentioning

confidence: 99%

The double low-mass white dwarf eclipsing binary system J2102–4145 and its possible evolution

Antunes Amaral,

Munday,

Vučković

et al. 2024

A&A

View full text Add to dashboard Cite

In recent years, about 150 low-mass white dwarfs (WDs), typically with masses below $0.4M_ odot $, have been discovered. The majority of these low-mass WDs are observed in binary systems as they cannot be formed through single-star evolution within Hubble time. In this work, we present a comprehensive analysis of the double low-mass WD eclipsing binary system J2102-4145. Our investigation encompasses an extensive observational campaign, resulting in the acquisition of approximately 28 hours of high-speed photometric data across multiple nights using NTT/ULTRACAM, SOAR/Goodman, and SMARTS-1m telescopes. These observations have provided critical insights into the orbital characteristics of this system, including parameters such as inclination and orbital period. To disentangle the binary components of J2102-4145, we employed the GRID spectral fitting method with GMOS/Gemini-South and X-Shooter data. Additionally, we used the PHOEBE package for light curve analysis on NTT/ULTRACAM high-speed time-series photometry data to constrain the binary star properties. Our analysis unveils remarkable similarities between the two components of this binary system. For the primary star, we determine $T_ eff,1 $ K, $ g_1 = 7.36 $R_1=0.0211 and $M_1 = 0.375 odot $, while, the secondary star is characterised by $T_ eff,2 $ K, $ g_2 = 7.32 $\,R$_ and $M_2 = 0.314 odot $. Furthermore, we found a notable discrepancy between $T_ eff $ and $R$ of the less massive WD, compared to evolutionary sequences for WDs from the literature, which has significant implications for our understanding of WD evolution. We discuss a potential formation scenario for this system which might explain this discrepancy and explore its future evolution. We predict that this system will merge in sim 800\,Myr, evolving into a helium-rich hot subdwarf star and later into a hybrid He/CO WD.

show abstract

“…Pulsations. Both DA and DB white dwarfs with temperatures close to that of Janus have been observed to pulsate 54,55 . At these temperatures (or slightly colder ones), two mechanisms are known that can drive pulsations: on one hand, the V777 Her (or DBV) instability strip lays between ∼ 20, 000 and ∼ 30, 000 K and is caused by partial He ionisation in the atmosphere of DB white dwarfs; on the other hand, it has been suggested that, in transitioning white dwarfs at the red end of the DB gap, pulsational instabilities can be driven by radiative heat exchange in the superadiabatic atmospheric layer 56,57 .…”

Section: White Dwarf Modelsmentioning

confidence: 99%

A rotating white dwarf with two faces

Caiazzo

Burdge

Ferrario

et al. 2022

Preprint

View full text Add to dashboard Cite

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterised by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink toward the centre, and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen, or, if the hydrogen content is low, helium. Helium-atmosphere white dwarfs account for about 20% of all white dwarfs; however, several mechanisms can compete with gravitational settling to change their surface composition as they cool, and the fraction of white dwarfs with helium atmospheres is not constant at all temperatures. This fraction is known to increase by a factor ~2.5 below a temperature of about 30,000 K; therefore, some white dwarfs that appear to have a hydrogen-dominated atmosphere above that temperature are bound to transition to a helium-dominated atmosphere as they cool below it. Here we report observations of ZTF J203349.8+322901.1, or ``Janus'', a white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. The peculiar double-faced nature of Janus is most likely caused by a small magnetic field, which creates an inhomogeneity in temperature, pressure, or mixing strength over the surface. We appear to have caught a white dwarf as it is undergoing the transition from a hydrogen-dominated to a helium-dominated atmosphere. If this is the case, Janus might be the most extreme member of a class of magnetic transitioning white dwarfs and could help shed light on the physical mechanisms behind white dwarf spectral evolution.

show abstract

Pulsation in the white dwarf HE 1017−1352: confirmation of the class of hot DAV stars

Cited by 6 publications

References 19 publications

Asteroseismology across the HR diagram

Asteroseismology across the HR diagram

The double low-mass white dwarf eclipsing binary system J2102–4145 and its possible evolution

A rotating white dwarf with two faces

Contact Info

Product

Resources

About