On a Method of Determining the Absolute Dimensions of an Algol Variable Star

Roberts, Alex. W.

doi:10.1093/mnras/66.3.123

Cited by 9 publications

(5 citation statements)

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“…Another more plausible scenario to account for such a huge amplitude is that the variability we are detecting is the consequence of the O'Connell effect (O'Connell 1951;Milone 1968;Johnston et al 2019), whereby ellipsoidally-modulated binaries are frequently found to present uneven maxima in their light curves. It had previously been suggested that this could be the result of a so-called "periastron effect" in which the binaries are somewhat eccentric and experience an increased irradiation effect close to periastron (Roberts 1906), however it quickly became clear that in most cases the brighter maxima does not coincide with periastron (Dugan 1916), or that their orbits were essentially circular (O'Connell 1936), thus ruling out this hy-pothesis. It is now generally thought that the effect is likely due to a hot or cool spot (or spots) on one of the component stars, perhaps via accretion streams which would naturally lead to hot spots (Wilsey & Beaky 2009).…”

Section: Pg 1034+001mentioning

confidence: 99%

Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1

Aller

Lillo-Box

Jones

et al. 2020

A&A

196

110

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Context. It is now clear that binarity plays a crucial role in many aspects of planetary nebulae (PNe), particularly the striking morphologies that they show. To date, there are ∼ 60 bCSPNe known. However, both theory and observation indicates that this represents only the tip of the iceberg, with the Galactic PN population hosting orders of magnitude more. Aims. We are involved in a search for new bCSPNe to enhance the statistical validation of the key role of binarity in the formation and shaping of PNe. New discoveries of bCSPNe and their characterization have important implications not only in understanding PN evolution but also in understanding binary evolution and the poorly-understood common-envelope phase. Methods. We used data from the TESS satellite to search for variability in the eight CSPNe that belong to the two-minute cadence preselected targets in Cycle 1, which have available pipeline-extracted light curves. We identified strong periodicities and analysed them in the context of the binary scenario. Results. All the CSPNe but one (Abell 15) show clear signs of periodic variability in TESS. The cause of this variability can be attributed to different effects, some of them requiring the presence of a companion star. We find simple sinusoidal modulations in several of the systems, compatible to irradiation effects. In addition, two of the central stars (PG 1034+001 and NGC 5189) also show photometric variations due to ellipsoidal variations and other signs of variability probably caused by star spots and/or relativistic Doppler-beaming. Especially interesting is the case of the well-studied Helix Nebula, in which we constructed a series of binary models to explain the modulations we see in the light curve. We find that the variability constrains the possible companion to be very low-mass main-sequence star or sub-stellar object. We also identify with a great detail the individual pulsation frequencies of NGC 246.

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Section: Pg 1034+001mentioning

confidence: 99%

Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1

Aller

Lillo-Box

Jones

et al. 2020

A&A

196

110

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“…At the quadrature phases (f = 0.25, 0.75 for circular orbits), we see the stars side-by-side, so a difference in brightness implies that one hemisphere of a component emits a different amount of radiation than the other hemisphere. Roberts (1906) first discussed the O'Connell effect, where he attributed it to stars in an eccentric orbit becoming tidally distorted near periapsis. His theory did not explain the presence of the O'Connell effect in systems with circular orbits, however, and is no longer considered a likely cause of the O'Connell effect in most systems.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Kepler Eclipsing Binaries Displaying a Significant O’Connell Effect

Knote

Caballero-Nieves

Gokhale

et al. 2022

ApJS

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The O’Connell effect—the presence of unequal maxima in eclipsing binaries—remains an unsolved riddle in the study of close binary systems. The Kepler space telescope produced high-precision photometry of nearly 3000 eclipsing binary systems, providing a unique opportunity to study the O’Connell effect in a large sample and in greater detail than in previous studies. We have characterized the observational properties—including temperature, luminosity, and eclipse depth—of a set of 212 systems (7.3% of Kepler eclipsing binaries) that display a maxima flux difference of at least 1%, representing the largest sample of O’Connell effect systems yet studied. We explored how these characteristics correlate with each other to help understand the O’Connell effect’s underlying causes. We also describe some system classes with peculiar light-curve features aside from the O’Connell effect (∼24% of our sample), including temporal variation and asymmetric minima. We found that the O’Connell effect size’s correlations with period and temperature are inconsistent with Kouzuma's starspot study. Up to 20% of systems display the parabolic eclipse timing variation signal expected for binaries undergoing mass transfer. Most systems displaying the O’Connell effect have the brighter maximum following the primary eclipse, suggesting a fundamental link between which maximum is brighter and the O’Connell effect’s physical causes. Most importantly, we find that the O’Connell effect occurs exclusively in systems where the components are close enough to significantly affect each other, suggesting that the interaction between the components is ultimately responsible for causing the O’Connell effect.

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“…It was suggested to be caused by tidal effects and an increase in mutual radiation at periastron between stars moving in eccentric orbits (the so-called periastron effect in close eclipsing binaries) by Roberts (1906) long time ago. However, O'Connell (1951) pointed out that the effect had no connection with orbital eccentricity but caused by the circumstellar dust and gas.…”

Section: Introductionmentioning

confidence: 99%

The first photometric analysis of the W-subtype contact binary UCAC4 436-062932 with O’Connell effect

et al. 2016

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Two sets of light curves in V R c I c bands for a newly discovered binary system UCAC4 436-062932 are obtained and analyzed using the Wilson-Devinney (W-D) code. The two sets of light curves get almost consistent results. The determined mass ratio is about q = 2.7 and the less massive component is nearly 250K hotter than the more massive one. The solutions conclude that UCAC4 436-062932 is a W-subtype shallow contact (with a contact degree of f = 20 %) binary system. Since the O'Connell effect appears on one set of the light curves, theories proposed to explain the effect are discussed. We assume that spot model may be the more plausible one to the O'Connell effect appeared on the asymmetric light curves of the binary system UCAC4 436-062932. Therefore, we add a cool spot on the surface of the more massive star (component with lower effective temperature) and get a quite approving results for the light curve fitting. It will provide evidence to support the spot model in the explanatory mechanism of O'Connell effect.

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On a Method of Determining the Absolute Dimensions of an Algol Variable Star

Cited by 9 publications

References 0 publications

Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1

Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1

Characteristics of Kepler Eclipsing Binaries Displaying a Significant O’Connell Effect

The first photometric analysis of the W-subtype contact binary UCAC4 436-062932 with O’Connell effect

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