Radiation-driven winds of hot luminous stars

Hoffmann, T. L.; Pauldrach, A. W. A.; Kaschinski, C. B.

doi:10.1051/0004-6361/201220881

Cited by 4 publications

(14 citation statements)

References 33 publications

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“…However, radiation-hydrodynamical models of Pauldrach et al (2004) argued that (i) the dependence of stellar luminosity with mass is smaller than expected and (ii) the central stars of some well-studied PN had luminosities 4.2 < log(L/L ) < 4.5 and masses right at the Chandrasaekhar limit. The reliability of their wind models have been reinforced by Kaschinski et al (2012) and Hoffmann et al (2016). Because of this quite disturbing finding any independent determination of the distance to the objects in question would be of utmost relevance not only for accurate determinations of stellar properties but also for checking the complicated physics underlying stellar wind models.…”

Section: Introductionmentioning

confidence: 99%

Expansion patterns and parallaxes for planetary nebulae

Schönberner

Balick

Jacob

2018

A&A

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Aims. We aim to determine individual distances to a small number of rather round, quite regularly shaped planetary nebulae by combining their angular expansion in the plane of the sky with a spectroscopically measured expansion along the line of sight. Methods. We combined up to three epochs of Hubble Space Telescope imaging data and determined the angular proper motions of rim and shell edges and of other features. These results are combined with measured expansion speeds to determine individual distances by assuming that line of sight and sky-plane expansions are equal. We employed 1D radiation-hydrodynamics simulations of nebular evolution to correct for the difference between the spectroscopically measured expansion velocities of rim and shell and of their respective shock fronts. Results. Rim and shell are two independently expanding entities, driven by different physical mechanisms, although their model-based expansion timescales are quite similar. We derive good individual distances for 15 objects, and the main results are as follows: (i) distances derived from rim and shell agree well; (ii) comparison with the statistical distances in the literature gives reasonable agreement; (iii) our distances disagree with those derived by spectroscopic methods; (iv) central-star “plateau” luminosities range from about 2000 L⊙ to well below 10 000 L⊙, with a mean value at about 5000 L⊙, in excellent agreement with other samples of known distance (Galactic bulge, Magellanic Clouds, and K648 in the globular cluster M 15); (v) the central-star mass range is rather restricted: from about 0.53 to about 0.56 M⊙, with a mean value of 0.55 M⊙. Conclusions. The expansion measurements of nebular rim and shell edges confirm the predictions of radiation-hydrodynamics simulations and offer a reliable method for the evaluation of distances to suited objects.

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Section: Introductionmentioning

confidence: 99%

Expansion patterns and parallaxes for planetary nebulae

Schönberner

Balick

Jacob

2018

A&A

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“…These variations stem from the linear dependence of the terminal velocity on the escape speed (Castor et al 1975, Lamers et al 1995, Crowther et al 2006). If real CSPN radii are larger than assumed here, as indicated by their larger luminosities derived from observations (Table 6) and from evolutionary models (Miller Bertolami 2016), then the predicted terminal velocities are in fact slightly lower than what was derived from observations (as shown by Pauldrach et al 2004, Kaschinski et al 2012, Hoffmann et al 2016). However, this problem is not strong because the increase in the luminosity by 0.3 dex would imply the decrease in the wind terminal velocity by just 20%.…”

Section: Comparison With Observationsmentioning

confidence: 60%

“…4 we compare our predicted wind mass-loss rates with observational and theoretical results for hydrogen-rich CSPNe as a function of effective temperature. For a reliable determination of mass-loss rates from observations, the inclusion of smallscale inhomogeneities (clumping) is important (Hoffmann et al 2016). The estimates of Pauldrach et al (2004) neglect the influence of clumping on the line profiles, while Herald & Bianchi (2011), Kudritzki et al (2006), and Hultzsch et al (2007) account for clumping.…”

Section: Comparison With Observationsmentioning

confidence: 99%

Stellar wind models of central stars of planetary nebulae

Krtička

Kubát

Krtičková

2020

A&A

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1 Ústav teoretické fyziky a astrofyziky, Masarykova univerzita, Kotlářská 2, CZ-611 37 Brno, Czech Republic 2 Astronomický ústav, Akademie vědČeské republiky, Fričova 298, CZ-251 65 Ondřejov, Czech Republic Received ABSTRACTContext. Fast line-driven stellar winds play an important role in the evolution of planetary nebulae, even though they are relatively weak. Aims. We provide global (unified) hot star wind models of central stars of planetary nebulae. The models predict wind structure including the mass-loss rates, terminal velocities, and emergent fluxes from basic stellar parameters. Methods. We applied our wind code for parameters corresponding to evolutionary stages between the asymptotic giant branch and white dwarf phases for a star with a final mass of 0.569 M ⊙ . We study the influence of metallicity and wind inhomogeneities (clumping) on the wind properties. Results. Line-driven winds appear very early after the star leaves the asymptotic giant branch (at the latest for T eff ≈ 10 kK) and fade away at the white dwarf cooling track (below T eff = 105 kK). Their mass-loss rate mostly scales with the stellar luminosity and, consequently, the mass-loss rate only varies slightly during the transition from the red to the blue part of the Hertzsprung-Russell diagram. There are the following two exceptions to the monotonic behavior: a bistability jump at around 20 kK, where the massloss rate decreases by a factor of a few (during evolution) due to a change in iron ionization, and an additional maximum at about T eff = 40 − 50 kK. On the other hand, the terminal velocity increases from about a few hundreds of km s −1 to a few thousands of km s −1 during the transition as a result of stellar radius decrease. The wind terminal velocity also significantly increases at the bistability jump. Derived wind parameters reasonably agree with observations. The effect of clumping is stronger at the hot side of the bistability jump than at the cool side. Conclusions. Derived fits to wind parameters can be used in evolutionary models and in studies of planetary nebula formation. A predicted bistability jump in mass-loss rates can cause the appearance of an additional shell of planetary nebula.

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“…The systemic velocity of the orbit (70.45±0.13 km s −1 ) is in excellent agreement with the the systemic velocity of the nebula ( Bianchi (2011) assume a canonical 0.6 M . We do not favour any particular value for the primary mass given the complexities associated with the model atmosphere analyses of the central star of NGC 2392 (see Hoffmann et al 2016 for a detailed review and discussion). We can also determine whether the primary may experience Roche lobe overflow based on the orbital parameters.…”

Section: Results and Analysismentioning

confidence: 93%

The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392

Miszalski

Manick²,

Winckel³

et al. 2019

Publ. Astron. Soc. Aust.

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The Chandra X-ray Observatory has detected relatively hard X-ray emission from the central stars of several planetary nebulae (PNe). A subset have no known late-type companions, making it very difficult to isolate which of several competing mechanisms may be producing the X-ray emission. The central star of NGC 2392 is one of the most vexing members, with substantial indirect evidence for a hot white dwarf (WD) companion. Here we report on the results of a radial velocity (RV) monitoring campaign of its central star with the HERMES échelle spectrograph of the Flemish 1.2 m Mercator telescope. We discover a single-lined spectroscopic binary with an orbital period of 1.902208 ± 0.000013 d and a RV semi-amplitude of 9.96 ± 0.13 km s −1 . The high degree of nebula ionisation requires a WD companion (M 0.6M ), which the mass-function supports at orbital inclinations 7 deg, in agreement with the nebula orientation of 9 deg. The hard component of the X-ray spectrum may be explained by the companion accreting mass from the wind of the Roche lobe filling primary, while the softer component may be due to colliding winds. A companion with a stronger wind than the primary could produce the latter and would be consistent with models of the observed diffuse X-ray emission detected in the nebula. The diffuse X-rays may also be powered by the jets of up to 180 km s −1 and active accretion would imply that they could be the first active jets of a post-common-envelope PN, potentially making NGC 2392 an invaluable laboratory to study jet formation physics. The 1.9 d orbital period rules out a double-degenerate merger leading to a Type Ia supernova and the weak wind of the primary likely also precludes a single-degenerate scenario. We suggest that a hard X-ray spectrum, in the absence of a late-type companion, could be a powerful tool to identify accreting WD companions.

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Radiation-driven winds of hot luminous stars

Abstract: Radiation-driven winds of hot luminous stars XVIII. The unreliability of stellar and wind parameter determinations from optical vs. UV spectral analysis of selected central stars of planetary nebulae and the possibility of some CSPNs as single-star supernova Ia progenitors

Cited by 4 publications

References 33 publications

Expansion patterns and parallaxes for planetary nebulae

Expansion patterns and parallaxes for planetary nebulae

Stellar wind models of central stars of planetary nebulae

The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392

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