On the post-common-envelope central star of the planetary nebula NGC 2346

Brown, A.; Jones, David; Boffin, H. M. J.; Winckel, H. Van

doi:10.1093/mnras/sty2986

Cited by 16 publications

(16 citation statements)

References 37 publications

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“…The companions' radii were derived using R2/R = (M2/M ) 0.8 (Torres et al 2010), which can be shown to be reasonably close to the measured values when such values exist, even accounting for the fact that post-CE companions tend to be larger than their mass would dictate due to irradiation by the primary (De Marco et al 2008), or by recent accretion during the CE phase (Jones et al 2015). In at least one case, V651 Mon, Brown et al (2019) strongly suspects that the secondary is on the subgiant branch and therefore quite a bit larger than our assumption. The final separation, a f , is that derived from the observed period, this could be somewhat smaller than the one after the CE event because of magnetic braking (Zorotovic et al 2011a), though not enough to shift the data points in our logarithmic plots.…”

Section: The Observational and Reconstructed Datamentioning

confidence: 63%

“…In addition, the nebula can be used to suggest, though not guarantee, that the giant was on the asymptotic giant branch (AGB) rather than on the red giant branch (RGB) at the time of the CE, something that is less certain for other binaries where Mc 0.47 M (see below). All the PN we use are those listed in De Marco et al (2011) with the addition of 10 objects: UU Sge and KV Vel, V664 Cas and A 65 (as listed by Davis et al 2010), HaTr7 andESO 330-9 (Hillwig et al 2017), M3-1 (Jones et al 2019), Hen 2-155 (Jones et al 2015), Sp 1 (Hillwig et al 2016b) and V651 Mon (as recently revised by Brown et al 2019, note that for this object the companion may not be a main sequence star but instead a subgiant, if so then the secondary would be much closer to filling its Roche radius than we have listed in Table A2). Finally, we include all the sdO and sdB objects listed by Davis et al (2010) and most of those listed by Schreiber & Gänsicke (2003), with the exclusion of MT Ser and V477 Lyr.…”

Section: The Observational and Reconstructed Datamentioning

confidence: 99%

“…The PN shape is indistinct as the nebula is large but faint, in line with an RGB origin. V651 Mon (better known by its nebular name, NGC2346) has a mass of 0.46 M , right at the limit and with a large uncertainty (Brown et al 2019). Although we have carried out a post-RGB reconstruction as also advised by Brown et al (2019), this PN is distinctly bipolar and looks a lot more like a bona fide PN, throwing some further uncertainty on the quantities reconstructed for this object.…”

Section: Post-ce Binaries With Planetary Nebulaementioning

confidence: 99%

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Speaking with one voice: simulations and observations discuss the common envelope α parameter

Iaconi

Marco

2019

Monthly Notices of the Royal Astronomical Society

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We present a comparative study between the results of most hydrodynamic simulations of the common envelope binary interaction to date and observations of post common envelope binaries. The goal is to evaluate whether this dataset indicates the existence of a formula that may predict final separations of post-common envelope systems as a function of precommon envelope parameters. Some of our conclusions are not surprising while others are more subtle. We find that: (i) Values of the final orbital separation derived from common envelope simulations must at this time be considered upper limits. Simulations that include recombination energy do not seem to have systematically different final separations; these and other simulations imply α CE < 0.6 − 1.0. At least one simulation, applicable to doubledegenerate systems, implies α CE < 0.2. (ii) Despite large reconstruction errors, the post-RGB observations reconstructed parameters are in agreement with some of the simulations. The post-AGB observations behave instead as if they had a systematically lower value of α CE . The lack of common envelope simulations with low mass AGB stars leaves us with no insight as to why this is the case. (iii) The smallest mass companion that survives the common envelope with intermediate mass giants is 0.05-0.1 M . (iv) Observations of binaries with separations larger than ∼10 R , tend to have high M 2 /M 1 mass ratios and may go through a relatively long phase of unstable Roche lobe mass transfer followed by a weakened common envelope (or with no common envelope at all). (v) The effect of the spatial resolution and of the softening length on simulation results remains poorly quantified.

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Section: The Observational and Reconstructed Datamentioning

confidence: 63%

Section: The Observational and Reconstructed Datamentioning

confidence: 99%

Section: Post-ce Binaries With Planetary Nebulaementioning

confidence: 99%

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Speaking with one voice: simulations and observations discuss the common envelope α parameter

Iaconi

Marco

2019

Monthly Notices of the Royal Astronomical Society

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“…In the right panel we show a comparison with the rotational periods of pulsating white dwarfs (light green with dashed contours, values taken from Kawaler 2004;Hermes et al 2017a) and apparently single magnetic white dwarfs (bold yellow lines, values taken from Ferrario et al 2015). We note that there are also a few longer period magnetic white dwarfs (Putney & Jordan 1995;Bergeron et al 1997;Schmidt et al 1999;Kawka & Vennes 2012) and PCE binary central stars (Miszalski et al 2018a,b;Brown et al 2019), which we omit from Fig. 8 for better visibility.…”

Section: Periodsmentioning

confidence: 96%

Mysterious, Variable, and Extremely Hot: White Dwarfs Showing Ultra-High Excitation Lines I. Photometric Variability

Reindl,

Schaffenroth,

Filiz

et al. 2021

Preprint

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Context. About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. O viii) in their optical spectra when entering the white dwarf cooling sequence. This is something that has never been observed in any other astrophysical object, and challenges our understanding of the late stages of stellar evolution since decades. The recent discovery of a both spectroscopic and photometric variable UHE white dwarf led to the speculation that the UHE lines might be created in a shock-heated circumstellar magnetosphere. Aims. We aim to gain a better understanding of these mysterious objects by studying the photometric variability of the whole population of UHE white dwarfs, and white dwarfs showing only the He ii line problem, as both phenomena are believed to be connected. Methods. We investigate (multi-band) light curves from several ground-and space-based surveys of all 16 currently known UHE white dwarfs (including one newly discovered) and eight white dwarfs that show only the He ii line problem. Results. We find that 75 +8 −13 % of the UHE white dwarfs, and 75 +9 −19 % of the He ii line problem white dwarfs are significantly photometrically variable, with periods ranging from a 0.22 d to 2.93 d and amplitudes from a few tenth to a few hundredth mag. The high variability rate is in stark contrast to the variability rate amongst normal hot white dwarfs (we find 9 +4 −2 %), marking UHE and He ii line problem white dwarfs as a new class of variable stars. The period distribution of our sample agrees with both the orbital period distribution of post-common envelope binaries and the rotational period distribution of magnetic white dwarfs if we assume that the objects in our sample will spin-up as a consequence of further contraction. Conclusions. We found further evidence that UHE and He ii line problem white dwarfs are indeed related, as concluded from their overlap in the Gaia HRD, similar photometric variability rates, light curve shapes and amplitudes, as well as period distributions. The lack of increasing photometric amplitudes towards longer wavelengths, as well as the non-detection of optical emission lines arising from the highly irradiated face of a hypothetical secondary in the optical spectra of our stars, makes it seem unlikely that an irradiated late type companion is the origin of the photometric variability. Instead, we believe that spots on the surfaces of these stars and/or geometrical effects of circumstellar material might be responsible.

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“…Models such as the Grazing Envelope Evolution proposed by Soker (2015) and Shiber et al (2017), in which the companion grazes the envelope of the RGB or AGB star while both the orbital separation and the giant radius shrink simultaneously over the course of tens to hundreds of years, could perhaps help explain the phenomenon. A model along these lines could, for instance, provide some insight in the case of NGC 2346, a particularly massive SD system with a relatively long post-CE orbital period in which the primary is believed to be a post-RGB star (Brown et al 2019). At any rate, CE interaction would probably need to last long enough to allow for a considerable amount of the primary's envelope mass to get diluted into the ISM beyond detectability, in order for the presumed envelope mass at the time of a later "full" CE ejection to be reconciled with the mass of the observed nebulae.…”

Section: Samplementioning

confidence: 99%

The ionised and molecular mass of post-common-envelope planetary nebulae. The missing mass problem

Santander-García,

Jones,

Alcolea

et al. 2021

Preprint

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Context. Most planetary nebulae (PNe) show beautiful, axisymmetric morphologies despite their progenitor stars being essentially spherical. Close binarity is widely invoked to help eject an axisymmetric nebula, after a brief phase of engulfment of the secondary within the envelope of the Asymptotic Giant Branch (AGB) star, known as the common envelope (CE). The evolution of the AGB would thus be interrupted abruptly, its still quite massive envelope being rapidly ejected to form the PN, which a priori would be more massive than a PN coming from the same star, were it single. Aims. We aim at testing this hypothesis by investigating the ionised and molecular masses of a sample consisting of 21 post-CE PNe, roughly one fifth of the known total population of these objects, and comparing them to a large sample of 'regular' (i.e. not known to arise from close-binary systems) PNe. Methods. We have gathered data on the ionised and molecular content of our sample from the literature, and carried out molecular observations of several previously unobserved objects. We derive the ionised and molecular masses of the sample by means of a systematic approach, using tabulated, dereddened Hβ fluxes for finding the ionised mass, and 12 CO J=2−1 and J=3−2 observations for estimating the molecular mass. Results. There is a general lack of molecular content in post-CE PNe. Our observations only reveal molecule-rich gas around NGC 6778, distributed into a low-mass, expanding equatorial ring lying beyond the ionised broken ring previously observed in this nebula. The only two other objects showing molecular content (from the literature) are NGC 2346 and NGC 7293. Once we derive the ionised and molecular masses, we find that post-CE PNe arising from Single-Degenerate (SD) systems are just as massive, on average, as the 'regular' PNe sample, whereas post-CE PNe systems arising from Double-Degenerate (DD) systems are considerably more massive, and show substantially larger linear momenta and kinetic energy than SD systems and 'regular' PNe. Reconstruction of the CE of four objects, for which a wealth of data on the nebulae and complete orbital parameters are available, further suggests that the mass of SD nebulae actually amounts to a very small fraction of the envelope of their progenitor stars. This leads to the uncomfortable question of where the rest of the envelope is and why we cannot detect it in the stars' vicinity, thus raising serious doubts on our understanding of these intriguing objects.

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On the post-common-envelope central star of the planetary nebula NGC 2346

Cited by 16 publications

References 37 publications

Speaking with one voice: simulations and observations discuss the common envelope α parameter

Speaking with one voice: simulations and observations discuss the common envelope α parameter

Mysterious, Variable, and Extremely Hot: White Dwarfs Showing Ultra-High Excitation Lines I. Photometric Variability

The ionised and molecular mass of post-common-envelope planetary nebulae. The missing mass problem

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