Interacting Winds in Eclipsing Symbiotic Systems – The Case Study of EG Andromedae

Calabrò, Emanuele

doi:10.1007/s12036-014-9208-x

Cited by 4 publications

(7 citation statements)

References 29 publications

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“…These data show little or no evidence for a wind from the hot component. Coupled with the sub-Eddington luminosity of the hot component, L h /L edd 10 −3 , the UV and EUV data preclude models where colliding winds produce an emission line region between the two stars (e.g., Tomov 1995;Walder 1995;Calabrò 2014).…”

Section: Structure Of the Emission Line Regionmentioning

confidence: 99%

“…At optical minimum, the red giant occults the hot secondary and the strong emission lines (Stencel 1984;Vogel 1991;Crowley et al 2008). Despite a high quality orbit from optical and infrared absorption lines (Fekel et al 2000), it is not clear whether the optical variability is due to ellipsoidal variations (Wilson & Vaccaro 1997), illumination of the red giant photosphere or wind (Skopal et al 2007;Skopal 2008;Skopal et al 2012), or colliding winds from the primary and secondary stars (Walder 1995;Tomov 1995;Calabrò 2014).…”

Section: Introductionmentioning

confidence: 99%

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Eg Andromedae: A New Orbit and Additional Evidence for a Photoionized Wind

Kenyon

Garcia²

2016

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We analyze a roughly 20 yr set of spectroscopic observations for the symbiotic binary EG And. Radial velocities derived from echelle spectra are best-fit with a circular orbit having orbital period P = 483.3 ± 1.6 d and semi-amplitude K = 7.34 ± 0.07 km s −1 . Combined with previous data, these observations rule out an elliptical orbit at the 10σ level. Equivalent widths of H I Balmer emission lines and various absorption features vary in phase with the orbital period. Relative to the radius of the red giant primary, the apparent size of the H II region is consistent with a model where a hot secondary star with effective temperature T h ≈ 75,000 K ionizes the wind from the red giant.

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Section: Structure Of the Emission Line Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Eg Andromedae: A New Orbit and Additional Evidence for a Photoionized Wind

Kenyon

Garcia²

2016

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“…For EG And, some authors (e.g. Tomov 1995;Ikeda & Tamura 2004;Calabrò 2014) attempted to explain this variability within the theory of colliding winds in interacting binaries suggested by Girard & Willson (1987) and Luo et al (1990). However, the fact that a fraction of the giant's wind has to be transferred to and accreted onto the WD excludes the presence of colliding winds, at least at/around the orbital plane (see also Walder & Folini 2000;Kenyon & Garcia 2016).…”

Section: Introductionmentioning

confidence: 99%

Wind mass transfer in S-type symbiotic binaries III. Confirmation of a wind focusing in EG Andromedae from the nebular [OIII]λ5007 line

Shagatova,

Skopal,

Shugarov

et al. 2020

Preprint

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Context. The structure of the wind from the cool giants in symbiotic binaries carries important information for understanding the wind mass transfer to their white dwarf companions, its fuelling, and thus the path towards different phases of symbiotic-star evolution. Aims. In this paper, we indicate a non-spherical distribution of the neutral wind zone around the red giant (RG) in the symbiotic binary star, EG And. We concentrate in particular on the wind focusing towards the orbital plane and its asymmetry alongside the orbital motion of the RG. Methods. We achieved this aim by analysing the periodic orbital variations of fluxes and radial velocities of individual components of the Hα and [O iii] λ5007 lines observed on our high-cadence medium (R ∼ 11 000) and high-resolution (R ∼ 38 000) spectra.Results. The asymmetric shaping of the neutral wind zone at the near-orbital-plane region is indicated by: (i) the asymmetric course of the Hα core emission fluxes along the orbit; (ii) the presence of their secondary maximum around the orbital phase ϕ = 0.1, which is possibly caused by the refraction effect; and (iii) the properties of the Hα broad wing emission originating by Raman scattering on H 0 atoms. The wind is substantially compressed from polar directions to the orbital plane as constrained by the location of the [O iii] λ5007 line emission zones in the vicinity of the RG at/around its poles. The corresponding mass-loss rate from the polar regions of 10 −8 M ⊙ yr −1 is a factor of 10 lower than the average rate of ≈10 −7 M ⊙ yr −1 derived from nebular emission of the ionised wind from the RG. Furthermore, it is two orders of magnitude lower than that measured in the near-orbital-plane region from Rayleigh scattering. Conclusions. The startling properties of the nebular [O iii] λ5007 line in EG And provides an independent indication of the wind focusing towards the orbital plane -the key to understanding the efficient wind mass transfer in symbiotic binary stars.

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“…The apical coordinates of a quasar can be related to its astronomical coordinates the right ascension α and the declination δ (that are known from the ICRF2 catalogue) by means of some equations derived from spherical astronomy [20,21]:…”

Section: The Apical Coordinate Systemmentioning

confidence: 99%

“…In particular, the spacecraft's velocity value V j + 1 at the time (j + 1) and the related aberrated coordinates can be obtained from the spacecraft's velocity V j and the aberrated coordinates at the time (j) by means of measurements of three quasars at least and some expressions derived from spherical astronomy [20,21]. The apical and aberrated coordinates of the velocities V 1 (j = 1) and V 2 are pointed out in Figure 3.…”

Section: The Aberrated Apical Coordinates At Relativistic Velocitiesmentioning

confidence: 99%

Spacecraft Guidance Sensing at Relativistic Velocities

Calabrò¹

2020

Advances in Spacecraft Attitude Control

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In this chapter a solution to the problem of planning an interstellar voyage at relativistic velocities by automatic control was proposed. To this aim, position and velocity of a relativistic interstellar spacecraft can be found by means of automatic measurements onboard of the aberrated angular distances between three quasars, at least. Indeed, this set can represent a reliable inertial reference frame due to the circumstance that quasars can be considered fixed in the space due to their large distances from Earth. To this aim, the so-called apical latitude and longitude of some quasars can be obtained from their right ascension α and declination δ in astronomical catalogues, using some mathematical expressions to provide the aberrated coordinates of a relativistic spacecraft during an interstellar space mission. The algorithm used in this study showed that the accuracy of determining the aberrated apical coordinates of a spacecraft increases significantly using quasars with aberrated apical latitude values lower than 45°in the direction of motion, suggesting that one or more normal-sized telescopes aboard the spacecraft can use quasars within a cone with angular aperture of about 45°, providing aberrated apical latitudes of the spacecraft with errors ranging from 10 À7 to 10 À9 .

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Interacting Winds in Eclipsing Symbiotic Systems – The Case Study of EG Andromedae

Cited by 4 publications

References 29 publications

Eg Andromedae: A New Orbit and Additional Evidence for a Photoionized Wind

Eg Andromedae: A New Orbit and Additional Evidence for a Photoionized Wind

Wind mass transfer in S-type symbiotic binaries III. Confirmation of a wind focusing in EG Andromedae from the nebular [OIII]λ5007 line

Spacecraft Guidance Sensing at Relativistic Velocities

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