The Emergence of a Neutral Wind Region in the Orbital Plane of Symbiotic Binaries during Their Outbursts

Skopal, A.

doi:10.3847/1538-3881/acd193

Cited by 3 publications

(2 citation statements)

References 85 publications

(138 reference statements)

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“…The fact that this region consists of the neutral wind from the giant (see above) is confirmed by the significant difference in N H values measured around the superior and the inferior conjunction of the giant. This is because of measuring N H in the direction to the WD, while the source of neutral hydrogen is associated with the red giant (see Skopal, 2023). Also, the model of N H values from Fig.…”

Section: Emergence Of a Neutral Region In The Orbital Plane During Z ...mentioning

confidence: 99%

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Exploring outbursts of accreting white dwarfs in symbiotic binaries -- basic concept

Skopal

2024

caosp

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In this contribution I summarize the main characteristics and effects that are observed during outbursts of symbiotic stars: properties of the hot-and warm-type outbursts, enhanced mass outflow occasionally followed by ejection of bipolar jets, and the emergence of a neutral near-orbital-plane region. The results presented were largely obtained using small telescopes, supplemented by observations from the archives of terrestrial and space observatories.

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Section: Emergence Of a Neutral Region In The Orbital Plane During Z ...mentioning

confidence: 99%

“…Owing to the high densities of the giant's wind in the orbital plane, the hydrogen recombination process occurs within minutes to days. As a result, a neutral wind region emerges in the orbital plane during outbursts of SySts (see Skopal, 2023).…”

Section: Emergence Of a Neutral Region In The Orbital Plane During Z ...mentioning

confidence: 99%

Exploring outbursts of accreting white dwarfs in symbiotic binaries -- basic concept

Skopal

2024

caosp

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Density asymmetry and wind velocities in the orbital plane of the symbiotic binary EG Andromedae

Shagatova¹,

Skopal²,

Kundra³

et al. 2023

A&A

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Context. Non-dusty late-type giants without a corona and large-scale pulsations represent objects that do not fulfil the conditions under which standard mass-loss mechanisms can be applied efficiently. Despite the progress during the past decades, the driving mechanism of their winds is still unknown. Aims. One of the crucial constraints of aspiring wind-driving theories can be provided by the measured velocity and density fields of outflowing matter. The main goal of this work is to match the radial velocities of absorbing matter with a depth in the red giant (RG) atmosphere in the S-type symbiotic star EG And. Methods. We measured fluxes and radial velocities of ten Fe I absorption lines from spectroscopic observations with a resolution of ≈30 000. At selected orbital phases, we modelled their broadened profiles, including all significant broadening mechanisms. Results. The selected Fe I absorption lines at 5151–6469 Å originate at a radial distance ≈1.03 RG radii from its centre. The corresponding radial velocity is typically ≈1 km s−1, which represents a few percent of the terminal velocity of the RG wind. The high scatter of the radial velocities of several km s−1 in the narrow layer of the stellar atmosphere points to the complex nature of the near-surface wind mass flow. The average rotational velocity of 11 km s−1 implies that the rotation of the donor star can contribute to observed focusing the wind towards the orbital plane. The orbital variability of the absorbed flux indicates the highest column densities of the wind in the area between the binary components, even though the absorbing neutral material is geometrically more extended from the opposite side of the giant. This wind density asymmetry in the orbital plane region can be ascribed to gravitational focusing by the white dwarf companion. Conclusions. Our results suggest that both gravitational and rotational focusing contribute to the observed enhancement of the RG wind towards the orbital plane, which makes mass transfer by the stellar wind highly efficient.

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Wind-mass transfer in S-type symbiotic binaries

Skopal,

Shagatova

2023

A&A

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Context. Observational indications of wind-mass transfer from an evolved giant to its distant white dwarf (WD) companion in symbiotic binaries are rare. Here, we present a way to examine the neutral wind from the giant in symbiotic binaries, which is temporarily observable throughout the orbital plane during outbursts. Aims. We find that the mass-loss rate from giants in the orbital plane of S-type symbiotic binaries is high, indicating a high wind-mass-transfer efficiency in these systems. Methods. We modeled hydrogen column densities in the orbital plane between the observer and the WD for all suitable eclipsing S-type symbiotic binaries during outbursts in any orbital phase. Results. The mass-loss rate from the giant in the orbital plane is on the order of 10−6 M⊙ yr−1, which is a factor of ∼10 higher than rates derived from nebular emission produced by the ionized wind from normal giants in symbiotic stars. This finding suggests a substantial focusing of the giant’s wind toward the orbital plane and, thus, its effective transfer onto the WD companion. Conclusions. Our finding suggests that wind focusing on the orbital plane may be a common property of winds from giants in S-type symbiotic stars. Such wind-focusing resolves a long-standing problem of the large energetic output from their burning WDs and deficient fueling by the giant via a standard Bondi–Hoyle accretion. It also allows the WD to grow faster in mass, which lends support to the possibility that S-type symbiotic binaries are progenitors of Type Ia supernovae.

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The Emergence of a Neutral Wind Region in the Orbital Plane of Symbiotic Binaries during Their Outbursts

Cited by 3 publications

References 85 publications

Exploring outbursts of accreting white dwarfs in symbiotic binaries -- basic concept

Exploring outbursts of accreting white dwarfs in symbiotic binaries -- basic concept

Density asymmetry and wind velocities in the orbital plane of the symbiotic binary EG Andromedae

Wind-mass transfer in S-type symbiotic binaries

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