scholarly journals Spectral and photometric analysis of the eclipsing binary ε Aurigae prior to and during the 2009-2011 eclipse

2017 ◽  
Author(s):  
P. Chadima ◽  
M. Šlechta ◽  
P. Škoda ◽  
P. Harmanec ◽  
P. D. Bennett ◽  
...  
Keyword(s):  
Spectral Lines ◽  
Primary Star ◽  
Photometric Variability ◽  
Eclipsing Binary ◽  
Photometric Observations ◽  
Plausible Values ◽  
Ubv Photometry ◽  
Dominant Period ◽  
First Contact ◽  
Rule Out

A series of 353 red electronic spectra (from three observatories, mostly from 6300 to 6700 )A obtained between 1994 and 2010, and of 171 UBV photometric observations (from two observatories) of the 2010 eclipse, were analyzed in an effort to better understand ε Aur, the well-known, but still enigmatic eclipsing binary with the longest known orbital period (~27 yrs). The main results follow. (1) We attempted to recover a spectrum of the companion by disentangling the observed spectra of the ε Aur binary failed, but we were able to disentangle the spectrum of telluric lines and obtain a mean spectrum of the F-type primary star. The latter was then compared to a grid of synthetic spectra for a number of plausible values of Teff and log g, but a reasonably good match was not found. However, we conclude that the observed spectrum is that of a low gravity star. (2) We examined changes in the complex Halpha line profiles over the past 16 years, with particular emphasis on the 2009-2011 eclipse period, by subtracting a mean out-of-eclipse Halpha profile (appropriately shifted in radial velocity) from the observed spectra. We find that the dark disk around the unseen companion has an extended "atmosphere" that manifests itself via blueshifted and redshifted Halpha "shell" absorptions seen projected against the F star. Significantly, the Halpha shell line first appeared three years before first contact of the optical eclipse when the system was not far past maximum separation. (3) Analyses of radial velocities and central intensities of several strong, unblended spectral lines, as well as UBV photometry, demonstrated that these observables showed apparent multiperiodic variability during eclipse. The dominant period of 66.21d was common to all the observables, but with different phase shifts between these variables. This result strongly supports our earlier suggestion that the photometric variability seen during eclipse is intrinsic to the F star, and therefore, the idea of a central brightening due to a hole in the disk should be abandoned. Although variability on similar timescales is also seen in the spectrum and in photometry out of eclipse, we were unable to find a coherent periodicity in these data. Nevertheless, theseresults appear to rule out regular stellar pulsations as the cause of this variability. Based on spectra obtained at the Dominion Astrophysical Observatory, Ondrejov Observatory and Castanet-Tolosan Observatory and on UBV photometry gathered at the Hvar Observatory and Hopkins Phoenix Observatory.Tables 1 and 2 are only available at the CDS via anonymous ftp to cdarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/530/A146

scholarly journals The Rapidly Rotating Giants of the FK Comae-type

1981 ◽  
Vol 93 ◽  
pp. 177-178 ◽  
Author(s):  
B. W. Bopp ◽  
S. M. Rucinski
Keyword(s):  
Radial Velocity ◽  
Spectral Lines ◽  
Photometric Variability ◽  
Double Peaks ◽  
Photometric Observations ◽  
Hα Emission ◽  
Low Mass ◽  
Photometric Period ◽  
Asymmetrically Distributed ◽  
Erratic Behavior

We present new spectroscopic and photometric observations and discuss a small but important group of rapidly rotating G - K giants (FK Com=HD 117555, UZ Lib=BD−8°3999, HD 199178 possibly others) which are photometrically variable, show slightly redshifted and variable Ca II H and K emission and variable Hα emission, show rotationally broadened spectral lines (50–100 km/s), and yet show no large radial velocity variations. Possible explanations of the properties of these stars are discussed and coalescence of a W UMa binary system seems to be the most probable evolutionary state.The most extreme of the group, FK Com is discussed in detail. Its type, G2IIIa (Keenan, priv.comm.) implying MV=−1 (the IR indices are consistent with a giant) suggests a reduction of log g (relative to Sun) −1.5 to −2.5; this can be only marginally reconciled with the dimensions of about 5 Ro resulting from the photometric period 2.4 d. and Vrot sin i about 100 km/s. The photometric variability (0.05 in I, 0.07 in R) is most probably due to spots asymmetrically distributed in longitude. The brightness minima observed by Chugainov in 1966 and 1974 and the new minimum observed in 1979 (JD 2443949.025) can be phased with one period 2.3995±0.0002 d. The erratic behavior of rotationally broadened spectral lines precludes obtaining a radial velocity orbit but an upper limit of 25 km/s for any periodic variations implies that the secondary must be a very low mass object. The strong Hα emission is variable in relative intensity of its double peaks but has a constant full width in excess of 20 A. The full half width at base implies rotational velocities of the order of 570 km/s; the half separation of peaks implies 300 km/s. Existence of an excretion disc of the type suggested by Webbink is possible.

scholarly journals Confronting Stellar Evolution Models for Active and Inactive Solar-Type Stars: The Triple System V1061 Cygni

2006 ◽  
Vol 2 (S240) ◽  
pp. 658-665
Author(s):  
Guillermo Torres ◽  
Claud H. Sandberg Lacy ◽  
Laurence A. Marschall ◽  
Holly A. Sheets ◽  
Jeff A. Mader
Keyword(s):  
Stellar Evolution ◽  
Triple System ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Chromospheric Activity ◽  
Intermediate Data ◽  
Photometric Observations ◽  
K Current ◽  
Solar Type ◽  
The Masses

AbstractWe present spectroscopic and photometric observations of the chromospherically active (X-ray strong) eclipsing binary V1061 Cyg (P = 2.35 days) showing that it is in reality a hierarchical triple system. We combine these observations with Hipparcos intermediate data (abscissa residuals) to derive the outer orbit with a period of 15.8 yr. We determine accurate values for the masses, radii, and effective temperatures of the eclipsing binary components, as well as for the mass and temperature of the third star. For the primary we obtain M = 1.282 ± 0.015 M⊙, R = 1.615 ± 0.017 R⊙, Teff = 6180 ± 100 K, for the secondary M = 0.9315 ± 0.0068 M⊙, R = 0.974 ± 0.020 R⊙, Teff = 5300 ± 150 K, and for the tertiary M = 0.925 ± 0.036 M⊙ and Teff = 5670 ± 100 K. Current stellar evolution models agree well with the properties of the primary star, but show a large discrepancy in the radius of the secondary in the sense that the observed value is about 10% larger than predicted (a 5σ effect). We also find the secondary temperature to be ∼200 K cooler than indicated by the models. These discrepancies are quite remarkable considering that the secondary is only 7% less massive than the Sun, which is the calibration point of all stellar models. Similar differences with theory have been seen before for lower mass stars. We identify chromospheric activity as the likely cause of the effect. Inactive stars agree very well with the models, while active ones such as the secondary of V1061 Cyg appear systematically too large and too cool. Both of these differences are understood in terms of the effects of magnetic fields commonly associated with chromospheric activity.

The Eclipsing Binary WX Eridani

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.

scholarly journals Long-Term Multicolour Photometry of the Young Stellar Objects FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cygni

2015 ◽  
Vol 32 ◽  
Author(s):  
S. I. Ibryamov ◽  
E. H. Semkov ◽  
S. P. Peneva
Keyword(s):  
Gulf Of Mexico ◽  
Young Stellar Objects ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Photometric Variability ◽  
The North ◽  
Dense Molecular Cloud ◽  
Photometric Observations ◽  
All Optical

AbstractResults from long-term multicolour optical photometric observations of the pre-main-sequence stars FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cyg collected during the period from 1997 June to 2014 December are presented. The objects are located in the dense molecular cloud L935, named ‘Gulf of Mexico’, in the field between the North America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to define the reasons for the observed brightness variations. The presented paper is a part of our long-term photometric study of the young stellar objects in the region of ‘Gulf of Mexico’.

scholarly journals An Accretion-Disc Model for the Algol-Type Eclipsing Binary System AV Del

2011 ◽  
Vol 28 (1) ◽  
pp. 38-45 ◽  
Author(s):  
S. M. R. Ghoreyshi ◽  
J. Ghanbari ◽  
F. Salehi
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Outer Radius ◽  
Accretion Disc ◽  
Physical Parameters ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Disc Model ◽  
The Absolute

AbstractThis study inspects the light and radial-velocity curves of the eclipsing binary AV Del. In comparison with other studies already done, the study shows that the absolute elements, fundamental orbital and physical parameters of the system can be determined using the Wilson-Devinney code. Using these parameters, the configuration of the system is presented. Then, an accretion disc model for the system is introduced by using the shellspec code. The results indicate that AV Del is a semi-detached system in which an optically thick accretion disc is surrounding the primary star. The outer radius of the disc is 8.0 R⊙, corresponding to a distance of 1.1 R⊙ from the surface of the secondary. Also, the temperature of the disc is calculated to be T = 5700 K.

scholarly journals Photometric detection of internal gravity waves in upper main-sequence stars

2020 ◽  
Vol 640 ◽  
pp. A36 ◽  
Author(s):  
D. M. Bowman ◽  
S. Burssens ◽  
S. Simón-Díaz ◽  
P. V. F. Edelmann ◽  
T. M. Rogers ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Massive Stars ◽  
Pressure Fluctuations ◽  
Tangential Velocity ◽  
Chemical Species ◽  
Internal Gravity Waves ◽  
Spectral Lines ◽  
Photometric Variability ◽  
Near Surface ◽  
Photometric Detection

Context. Massive stars are predicted to excite internal gravity waves (IGWs) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. These IGWs are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationally. Aims. We aim to characterise the photometric detection of IGWs across a large number of O and early-B stars in the Hertzsprung–Russell diagram, and explain the ubiquitous detection of stochastic variability in the photospheres of massive stars. Methods. We combined high-precision time-series photometry from the NASA Transiting Exoplanet Survey Satellite with high-resolution ground-based spectroscopy of 70 stars with spectral types O and B to probe the relationship between the photometric signatures of IGWs and parameters such as spectroscopic mass, luminosity, and macroturbulence. Results. A relationship is found between the location of a star in the spectroscopic Hertzsprung–Russell diagram and the amplitudes and frequencies of stochastic photometric variability in the light curves of massive stars. Furthermore, the properties of the stochastic variability are statistically correlated with macroturbulent velocity broadening in the spectral lines of massive stars. Conclusions. The common ensemble morphology for the stochastic low-frequency variability detected in space photometry and its relationship to macroturbulence is strong evidence for IGWs in massive stars, since these types of waves are unique in providing the dominant tangential velocity field required to explain the observed spectroscopy.

scholarly journals Discovery of β Cep pulsations in the eclipsing binary V453 Cygni

2020 ◽  
Vol 497 (1) ◽  
pp. L19-L23 ◽  
Author(s):  
John Southworth ◽  
D M Bowman ◽  
A Tkachenko ◽  
K Pavlovski
Keyword(s):  
Physical Properties ◽  
Satellite Data ◽  
Binary Stars ◽  
Mass Measurement ◽  
Physical Processes ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Period Orbit ◽  
Orbital Frequency ◽  
Short Period

ABSTRACT V453 Cyg is an eclipsing binary containing 14 and 11 $\, {\rm M}_\odot$ stars in an eccentric short-period orbit. We have discovered β Cep-type pulsations in this system using Transiting Exoplanet Survey Satellite data. We identify seven significant pulsation frequencies, between 2.37 and 10.51 d−1, in the primary star. These include six frequencies that are separated by yet significantly offset from harmonics of the orbital frequency, indicating they are tidally perturbed modes. We have determined the physical properties of the system to high precision: V453 Cyg A is the first β Cep pulsator with a precise mass measurement. The system is a vital tracer of the physical processes that govern the evolution of massive single and binary stars.

scholarly journals The TESS light curve of the eccentric eclipsing binary 1SWASP J011351.29+314909.7 – no evidence for a very hot M-dwarf companion

2020 ◽  
Vol 498 (1) ◽  
pp. L15-L19
Author(s):  
Matthew I Swayne ◽  
Pierre F L Maxted ◽  
Vedad Kunovac Hodžić ◽  
Amaury H M J Triaud
Keyword(s):  
Light Curve ◽  
Effective Temperature ◽  
Binary Star ◽  
Mass Star ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Low Mass ◽  
Stellar Models ◽  
Eclipsing Binary Star ◽  
M Dwarf

ABSTRACT A 2014 study of the eclipsing binary star 1SWASPJ011351.29+314909.7 (J0113+31) reported an unexpectedly high effective temperature for the M-dwarf companion to the 0.95-M⊙ primary star. The effective temperature inferred from the secondary eclipse depth was ∼600 K higher than the value predicted from stellar models. Such an anomalous result questions our understanding of low-mass stars and might indicate a significant uncertainty when inferring properties of exoplanets orbiting them. We seek to measure the effective temperature of the M-dwarf companion using the light curve of J0113+31 recently observed by the Transiting Exoplanet Survey Satellite (TESS). We use the pycheops modelling software to fit a combined transit and eclipse model to the TESS light curve. To calculate the secondary effective temperature, we compare the best-fitting eclipse depth to the predicted eclipse depths from theoretical stellar models. We determined the effective temperature of the M dwarf to be Teff,2 = 3208 ± 43 K, assuming log g2 = 5, [Fe/H] = −0.4, and no alpha-element enhancement. Varying these assumptions changes Teff,2 by less than 100 K. These results do not support a large anomaly between observed and theoretical low-mass star temperatures.

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