BRITE photometry of the massive post-RLOF system HD149 404

Context. HD 149 404 is an evolved non-eclipsing O-star binary that has previously undergone a Roche lobe overflow interaction. Aims. Understanding some key properties of the system requires a determination of the orbital inclination and of the dimensions of the components. Methods. The BRITE-Heweliusz satellite was used to collect photometric data of HD 149 404. Additional photometry was retrieved from the SMEI archive. These data were analysed using a suite of period search tools. The orbital part of the lightcurve was modelled with the nightfall binary star code. The Gaia-DR2 parallax of HD 149 404 was used to provide additional constraints. Results. The periodograms reveal a clear orbital modulation of the lightcurve with a peak-to-peak amplitude near 0.04 mag. The remaining non-orbital part of the variability is consistent with red noise. The lightcurve folded with the orbital period reveals ellipsoidal variations, but no eclipses. The minimum when the secondary star is in inferior conjunction is deeper than the other minimum due to mutual reflection effects between the stars. Combined with the Gaia-DR2 parallaxes, the photometric data indicate an orbital inclination in the range of 23°–31° and a Roche lobe filling factor of the secondary larger than or equal to 0.96. Conclusions. The luminosity of the primary star is consistent with its present-day mass, whereas the more evolved secondary appears overluminous for its mass. We confirm that the primary’s rotation period is about half the orbital period. Both features most probably stem from the past Roche lobe overflow episode.

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Fluorescence and Chromospheric Activity of V471 Tau

International Astronomical Union Colloquium ◽

10.1017/s0252921100001366 ◽

2002 ◽

Vol 187 ◽

pp. 167-172

Author(s):

T.R. Vaccaro ◽

R.E. Wilson

Keyword(s):

Light Curve ◽

Radial Velocity ◽

Orbital Period ◽

White Dwarf ◽

Binary Star ◽

Star Model ◽

Orbital Inclination ◽

Orbital Parameters ◽

Maximum Emission ◽

Chromospheric Activity

AbstractThe red dwarf + white dwarf eclipsing binary V471 Tau shows a variable Hα feature that varies from absorption during eclipse to maximum emission during white dwarf transit. In 1998 we obtained simultaneous BVRI photometry and Hα spectroscopy, with thorough phase coverage of the 12.5 hour orbital period. A binary star model was used with our light curve, radial velocity, and Hα data to refine stellar and orbital parameters. Combined absorption-emission profiles were generated by the model and fit to the observations, yielding a red star radius of 0.94R⊙. Orbital inclination 78° is required with this size and other known parameters. The model includes three spots 1,000 K cooler than the surrounding photosphere. The variable Hα profile was modeled as a chromospheric fluorescing region (essentially on the surface of the red star) centered at the substellar point. Additional emission seen outside our modeled profiles may be large co-rotating prominences that complicate the picture.

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The Eclipses of the Close Binary Star BE UMa

International Astronomical Union Colloquium ◽

10.1017/s0252921100039464 ◽

1996 ◽

Vol 158 ◽

pp. 471-472

Author(s):

Janet H. Wood ◽

E. L. Robinson ◽

E.-H. Zhang

Keyword(s):

Light Curve ◽

High Speed ◽

Binary Star ◽

Light Curves ◽

Close Binary ◽

Primary Star ◽

Secondary Star ◽

Different Depths ◽

The Mean ◽

Close Binary Star

BE UMa is a close binary star, not transferring mass, with an extremely hot primary star irradiating the inner face of the cool secondary star. The light curve shows a large-amplitude, sinusoidal variation with a period of 2.29 d, and an eclipse that is centered on the minimum of the variation [1], [3]. According to [1], the eclipse is partial, not total. However, it has been argued [2] that the eclipse was really flat bottomed and thus total. This has important repercussions for the deduced model of the system. To resolve this issue we obtained simultaneous UBVR photometry of BE UMa using the Stiening 4-channel, high-speed photometer on the 82-inch telescope at McDonald Observatory. The mean light curves are shown in Fig. 1. The eclipse in all colours is round bottomed and partial. The different depths are caused by the different contribution from the red secondary star in each bandpass.

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The EBLM project – VII. Spin–orbit alignment for the circumbinary planet host EBLM J0608-59 A/TOI-1338 A

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2071 ◽

2020 ◽

Vol 497 (2) ◽

pp. 1627-1633 ◽

Cited By ~ 1

Author(s):

Vedad Kunovac Hodžić ◽

Amaury H M J Triaud ◽

David V Martin ◽

Daniel C Fabrycky ◽

Heather M Cegla ◽

...

Keyword(s):

Rotation Period ◽

Primary Component ◽

High Resolution Spectroscopy ◽

Spin Orbit ◽

Primary Star ◽

Secondary Star ◽

Short Period ◽

Low Mass ◽

Detached Binaries ◽

Binary Orbit

ABSTRACT A dozen short-period detached binaries are known to host transiting circumbinary planets. In all circumbinary systems so far, the planetary and binary orbits are aligned within a couple of degrees. However, the obliquity of the primary star, which is an important tracer of their formation, evolution, and tidal history, has only been measured in one circumbinary system until now. EBLM J0608-59/TOI-1338 is a low-mass eclipsing binary system with a recently discovered circumbinary planet identified by TESS. Here, we perform high-resolution spectroscopy during primary eclipse to measure the projected stellar obliquity of the primary component. The obliquity is low, and thus the primary star is aligned with the binary and planetary orbits with a projected spin–orbit angle β = 2${_{.}^{\circ}}$8 ± 17${_{.}^{\circ}}$1. The rotation period of 18.1 ± 1.6 d implied by our measurement of vsin i⋆ suggests that the primary has not yet pseudo-synchronized with the binary orbit, but is consistent with gyrochronology and weak tidal interaction with the binary companion. Our result, combined with the known coplanarity of the binary and planet orbits, is suggestive of formation from a single disc. Finally, we considered whether the spectrum of the faint secondary star could affect our measurements. We show through simulations that the effect is negligible for our system, but can lead to strong biases in vsin i⋆ and β for higher flux ratios. We encourage future studies in eclipse spectroscopy test the assumption of a dark secondary for flux ratios ≳1 ppt.

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The single-sided pulsator CO Camelopardalis

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa989 ◽

2020 ◽

Vol 494 (4) ◽

pp. 5118-5133 ◽

Cited By ~ 2

Author(s):

D W Kurtz ◽

G Handler ◽

S A Rappaport ◽

H Saio ◽

J Fuller ◽

...

Keyword(s):

Binary Stars ◽

Binary Star ◽

Spectral Energy Distribution ◽

Radial Velocities ◽

Close Binary ◽

Theoretical Modelling ◽

Spectral Energy ◽

Primary Star ◽

Pulsating Stars ◽

Secondary Star

ABSTRACT CO Cam (TIC 160268882) is the second ‘single-sided pulsator’ to be discovered. These are stars where one hemisphere pulsates with a significantly higher amplitude than the other side of the star. CO Cam is a binary star comprised of an Am δ Sct primary star with Teff = 7070 ± 150 K, and a spectroscopically undetected G main-sequence secondary star. The dominant pulsating side of the primary star is centred on the L1 point. We have modelled the spectral energy distribution combined with radial velocities, and independently the TESS light curve combined with radial velocities. Both of these give excellent agreement and robust system parameters for both stars. The δ Sct star is an oblique pulsator with at least four low radial overtone (probably) f modes with the pulsation axis coinciding with the tidal axis of the star, the line of apsides. Preliminary theoretical modelling indicates that the modes must produce much larger flux perturbations near the L1 point, although this is difficult to understand because the pulsating star does not come near to filling its Roche lobe. More detailed models of distorted pulsating stars should be developed. These newly discovered single-sided pulsators offer new opportunities for astrophysical inference from stars that are oblique pulsators in close binary stars.

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Optical observations and cyclops post-shock region modelling of the polar V348 Pav

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2445 ◽

2019 ◽

Vol 489 (3) ◽

pp. 4032-4042 ◽

Cited By ~ 1

Author(s):

Alexandre S Oliveira ◽

Claudia V Rodrigues ◽

Matheus S Palhares ◽

Marcos P Diaz ◽

Diogo Belloni ◽

...

Keyword(s):

Circular Polarization ◽

Orbital Period ◽

Rotation Period ◽

Line Emission ◽

Radial Velocities ◽

Optical Observations ◽

Proper Solution ◽

Radial Velocity Curve ◽

Orbital Inclination ◽

Post Shock

ABSTRACT Post-shock regions (PSR) of polar cataclysmic variables (CVs) produce most of their luminosity and give rise to high circular polarization in optical wavelengths and strong variability on the white dwarf (WD) rotation period, which are distinctive features of these systems. To investigate the polar candidate V348 Pav, we obtained a comprehensive observational set including photometric, polarimetric, and spectroscopic data, which was used to constrain the post-shock properties of the system. The object presents high circular polarization (∼30 per cent) and high He ii 4686 Å to H β line ratio, confirming it is a polar. From both radial velocities and light curves, we determined an orbital period of 79.98 min, close to the orbital period minimum of CVs. The H β radial velocity curve has a semi-amplitude of 141.4 ± 1.5 km s−1. Doppler tomography showed that most of the spectral line emission in this system is originated in the region of the companion star facing the WD, possibly irradiated by the emission related to the PSR. We modelled the PSR using the cyclops code. The PSR density and temperature profiles, obtained by a proper solution of the hydrothermodynamic equations, were used in a 3D radiative transfer solution that takes into account the system geometry. We could reproduce the V348 Pav B, V, R, and I photometric and polarimetric data using a model with a WD magnetic field of ∼28 MG, a WD mass of ∼0.85 M$\odot$, and a low (∼25°) orbital inclination. These values for the WD mass and orbital inclination are consistent with the measured radial velocities.

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Discovery of a pre-cataclysmic binary with unusual chromaticity of the eclipsed white dwarf by the GPX survey

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa547 ◽

2020 ◽

Vol 493 (4) ◽

pp. 5208-5217 ◽

Cited By ~ 1

Author(s):

Vadim Krushinsky ◽

Paul Benni ◽

Artem Burdanov ◽

Igor Antokhin ◽

Eleonora Antokhina ◽

...

Keyword(s):

White Dwarf ◽

Main Sequence ◽

Accretion Rate ◽

Binary Star ◽

Mass Ratio ◽

Orbital Inclination ◽

Common Envelope ◽

Secondary Star ◽

Photometric Observations ◽

Spot Activity

ABSTRACT We report the discovery of a relatively bright eclipsing binary system, which consists of a white dwarf (WD) and a main-sequence K7 star with clear signs of chromospheric and spot activity. The light curve of this system shows ∼0.2 mag ellipsoidal variability with a period of 0.297549 d and a short total eclipse of the WD. Based on our analysis of the spectral and photometric data, we estimated the parameters of the system. The K7V star is tidally deformed but does not fill its Roche lobe (the filling factor is about 0.86). The orbital inclination is i = $73{_{.}^{\circ}}1 \pm 0{_{.}^{\circ}}2$, and the mass ratio is q = M2/M1 ≈ 0.88. The parameters of the K7V star are M2 ≈ 0.64 M⊙, R2 = 0.645 ± 0.012R⊙, and T2 ≈ 4070 K. The parameters of the WD are M1 ≈ 0.72 M⊙, R1 = 0.013 ± 0.003R⊙, and T1 = 8700 ± 1100 K. Photometric observations in different bands revealed that the maximum depth of the eclipse is in the SDSS r filter, which is unusual for a system of a WD and a late main-sequence star. We suspect that this system is a product of the evolution of a common-envelope binary star, and that the WD accretes the stellar wind from the secondary star (the so-called low-accretion-rate polar, hereafter LARP).

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Nature of Circinus X-1

Australian Journal of Physics ◽

10.1071/ph790043 ◽

1979 ◽

Vol 32 (2) ◽

pp. 43 ◽

Cited By ~ 3

Author(s):

RF Haynes ◽

David L Jauncey ◽

I Lerche ◽

PG Murdin

Keyword(s):

Binary Star ◽

Compact Star ◽

Rotation Period ◽

Optical Emission ◽

Period Change ◽

Optical Observations ◽

Star Model ◽

Primary Star ◽

X Ray ◽

Shock Fronts

X-ray, radio and optical observations have been used to derive a binary star model for CircinusX-1. Mass transfer between the primary star (Mp ~ 20Mo) and the compact companion star (Me ~ Mo) triggers one or more expanding shock fronts in the vicinity of the compact star. These shocks produce the observed radio emission. Variable optical emission arises both from the changing Roche lobe surface in the highly eccentric system (e ~ 0�8) and from degradation of shock-produced X-ray photons to the optical band by material overlying the expanding shock. The X-ray radiation results from matter in the accretion disc dribbling down on to the surface of the compact star. Mass replenishment at a rate of 5 x 10-8 to 5 X 10-10 Mo per orbit (16�6 day period) occurs near periastron passage. The variation of the X-ray emission arises from absorption in the stellar wind of the primary star. The model predicts an apsidal rotation period for the elliptical orbit of 7-400 yr, an orbital circularization time of ~ 500 yr and a period change of about 0�5 day per 10 yr.

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The Eclipsing Binary WX Eridani

International Astronomical Union Colloquium ◽

10.1017/s0252921100073656 ◽

1979 ◽

Vol 46 ◽

pp. 385

Author(s):

M.B.K. Sarma ◽

K.D. Abhankar

Keyword(s):

Light Curve ◽

Spectral Type ◽

Orbital Period ◽

Primary Component ◽

Light Curves ◽

Absorption Feature ◽

Primary Star ◽

Eclipsing Binary ◽

The Times ◽

Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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