<i>Hubble</i>Space Telescope ultraviolet spectroscopy of the hottest known helium-rich pre-white dwarf KPD 0005+5106

Werner, K.; Rauch, T.

doi:10.1051/0004-6361/201527212

Cited by 10 publications

(4 citation statements)

References 34 publications

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“…Additionally, the He-rich pre-white dwarf KPD 0005+5106 has the abundances expected for a double degenerate merger. This both confirms that it is the descendant of an RCB star and reinforces the merger model for their origin (Werner & Rauch 2015). Observations of R Coronae Borealis, the prototype of its class, during a photometric minimum revealed a possible planetary nebula around the star (Clayton et al 2011).…”

Section: Introductionsupporting

confidence: 57%

An All-Sky Search For R Coronae Borealis Stars in ASAS-SN

Shields,

Jayasinghe,

Stanek

et al. 2018

Preprint

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We report the discovery of 19 new R Coronae Borealis (RCB) star and DY Per candidates with light curves from the All-Sky Automated Survey for Supernovae (ASAS-SN). We examined both an existing set of 1602 near/mid-IR selected candidates and an additional 2615 candidates selected to have near/mid-IR SEDs consistent with those of known R Coronae Borealis stars. We visually inspected the light curves for the characteristic variability of these systems.

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Section: Introductionsupporting

confidence: 57%

An All-Sky Search For R Coronae Borealis Stars in ASAS-SN

Shields,

Jayasinghe,

Stanek

et al. 2018

Preprint

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“…O(He) stars form a small group of 10 members in the T eff = 80 000-200 000 K range, log g = 5.0-6.7, and they have helium-dominated atmospheres with much less C and O content than PG1159 stars, typically below 1% (Reindl et al 2014b(Reindl et al , 2016De Marco et al 2015;Werner & Rauch 2015). Although they occupy the same region in the log g -T eff diagram as the PG1159 stars, the majority of them, that is, those not surrounded by a planetary nebula, are believed to be the merger product of two WDs.…”

Section: Introductionmentioning

confidence: 99%

Non-local thermodynamic equilibrium spectral analysis of five hot, hydrogen-deficient pre-white dwarfs

Werner¹,

Reindl

Dorsch

et al. 2022

A&A

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Hot, compact, hydrogen-deficient pre-white dwarfs (pre-WDs) with effective temperatures of Teff > 70 000 K and a surface gravity of 5.0 < logg < 7.0 are rather rare objects despite recent and ongoing surveys. It is believed that they are the outcome of either single star evolution (late helium-shell flash or late helium-core flash) or binary star evolution (double WD merger). Their study is interesting because the surface elemental abundances reflect the physics of thermonuclear flashes and merger events. Spectroscopically they are divided in three different classes, namely PG1159, O(He), or He-sdO. We present a spectroscopic analysis of five such stars that turned out to have atmospheric parameters in the range Teff = 70 000–80 000 K and logg = 5.2–6.3. The three investigated He-sdOs have a relatively high hydrogen mass fraction (10%) that is unexplained by both single (He core flash) and binary evolution (He-WD merger) scenarios. The O(He) star JL 9 is probably a binary helium-WD merger, but its hydrogen content (6%) is also at odds with merger models. We found that RL 104 is the ‘coolest’ (Teff = 80 000 K) member of the PG1159 class in a pre-WD stage. Its optical spectrum is remarkable because it exhibits C IV lines involving Rydberg states with principal quantum numbers up to n = 22. Its rather low mass (0.48−0.02+0.03 M⊙) is difficult to reconcile with the common evolutionary scenario for PG1159 stars due to it being the outcome of a (very) late He-shell flash. The same mass-problem faces a merger model of a close He-sdO plus CO WD binary that predicts PG1159-like abundances. Perhaps RL 104 originates from a very late He-shell flash in a CO/He WD formed by a merger of two low-mass He-WDs.

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“…Those CSPNe, as well as the PG 1159 stars with identified WD cores, will be counted among the spectroscopically identified WDs. KPD0005+5106, however, for example, is a known pre-WD object (Werner & Rauch 2015) with O(He) spectral type whose origin is still debated. It will be counted among the helium sdOs in this work.…”

Section: Wds Post-agbs and Cspnementioning

confidence: 99%

A 500 pc volume-limited sample of hot subluminous stars

Dawson,

Geier,

Heber

et al. 2024

A&A

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We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the Gaia space mission data release 3 (DR3). The sample comprises a total of 397 members, with 305 ($ 77<!PCT!>$) identified as hot subdwarf stars, including 83 newly discovered systems. Of these, we observe that 178 ($ are hydrogen-rich sdBs, 65 are sdOBs ($ 21<!PCT!>$), 32 are sdOs ($ 11<!PCT!>$), and 30 are He-sdO/Bs ($ 10<!PCT!>$). Among them, 48 ($ 16<!PCT!>$) exhibit an infrared excess in their spectral energy distribution fits, suggesting a composite binary system. The hot subdwarf population is estimated to be 90<!PCT!> complete, assuming that most missing systems are these composite binaries located within the main sequence (MS) in the Gaia colour-magnitude diagram (CMD). The remaining sources in the sample include cataclysmic variables (CVs), blue horizontal branch stars (BHBs), hot white dwarfs (WDs), and MS stars. We derived the mid-plane density $ $ and scale height $ h z $ for the non-composite hot subdwarf star population using a hyperbolic sechant profile (sech$^2$). The best-fit values are $ $ stars/pc3 and $ h z 62$ pc. When accounting for the composite-colour hot subdwarfs and their estimated completeness, the mid-plane density increases to $ $ stars/pc3. This corrected space density is an order of magnitude lower than predicted by population synthesis studies, supporting previous observational estimates.

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HubbleSpace Telescope ultraviolet spectroscopy of the hottest known helium-rich pre-white dwarf KPD 0005+5106

Cited by 10 publications

References 34 publications

An All-Sky Search For R Coronae Borealis Stars in ASAS-SN

An All-Sky Search For R Coronae Borealis Stars in ASAS-SN

Non-local thermodynamic equilibrium spectral analysis of five hot, hydrogen-deficient pre-white dwarfs

A 500 pc volume-limited sample of hot subluminous stars

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