scholarly journals THE FIRST DETAILED ANALYSIS ON THE ASTROPHYSICAL PROPERTIES OF THE ECCENTRIC BINARY V990 HER

2021 ◽  
Vol 57 (2) ◽  
pp. 363-379
Author(s):  
E. Kiran ◽  
V. Bakiş ◽  
H. Bakiş ◽  
Ö. L. Değirmenci
Keyword(s):  
Binary System ◽  
Detailed Analysis ◽  
Internal Structure ◽  
Orbital Period ◽  
Spectroscopic Data ◽  
Main Sequence ◽  
Physical Parameters ◽  
Apsidal Motion ◽  
Structure Constants ◽  
First Time

We present accurate physical parameters of the eccentric binary system V990 Her which has an orbital period of P=8.193315±0.000003 days using its photometric and spectroscopic data. The physical parameters of the components were derived as Teff1=8000±200 K, Teff2=7570±200 K, M1=2.01±0.07 Mʘ, M2=1.83±0.03 Mʘ, R1=2.22±0.02 Rʘ, R2=2.12±0.01 Rʘ, log(L1/Lʘ)=1.25±0.04, log(L2/Lʘ)=1.12±0.05. Our findings revealed that both components are slightly evolved from the zero-age main sequence with an age of 6.3×108 years. We estimated an apsidal motion with a period of U=14683±2936 years in the system and the internal structure constants of the components were derived for the first time.

scholarly journals Eclipsing spotted giant star with K2 and historical photometry

2018 ◽  
Vol 620 ◽  
pp. A189 ◽  
Author(s):  
K. Oláh ◽  
S. Rappaport ◽  
T. Borkovits ◽  
T. Jacobs ◽  
D. Latham ◽  
...  
Keyword(s):  
Binary System ◽  
Main Sequence ◽  
Rapid Evolution ◽  
Magnetic Activity ◽  
Primary Component ◽  
Physical Parameters ◽  
Giant Star ◽  
Eclipsing Binary ◽  
Giant Stars ◽  
Active Stars

Context. Stars can maintain their observable magnetic activity from the pre-main sequence (PMS) to the tip of the red giant branch. However, the number of known active giants is much lower than active stars on the main sequence (MS) since the stars spend only about 10% of their MS lifetime on the giant branch. Due to their rapid evolution it is difficult to estimate the stellar parameters of giant stars. A possibility for obtaining more reliable stellar parameters for an active giant arises when it is a member of an eclipsing binary system. Aims. We have discovered EPIC 211759736, an active spotted giant star in an eclipsing binary system during the Kepler K2 Campaign 5. The eclipsing nature allows us to much better constrain the stellar parameters than in most cases of active giant stars. Methods. We have combined the K2 data with archival HATNet, ASAS, and DASCH photometry, new spectroscopic radial velocity measurements, and a set of follow-up ground-based BVRCIC photometric observations, to find the binary system parameters as well as robust spot models for the giant at two different epochs. Results. We determined the physical parameters of both stellar components and provide a description of the rotational and long-term activity of the primary component. The temperatures and luminosities of both components were examined in the context of the Hertzsprung–Russell diagram. We find that both the primary and the secondary components deviate from the evolutionary tracks corresponding to their masses in the sense that the stars appear in the diagram at lower masses than their true masses. Conclusions. We further evaluate the proposition that traditional methods generally result in higher masses for active giants than what is indicated by stellar evolution tracks in the HR diagram. A possible reason for this discrepancy could be a strong magnetic field, since we see greater differences in more active stars.

Physical Parameters for a Contact Binary AY Aquarius

2014 ◽  
Vol 979 ◽  
pp. 20-22 ◽  
Author(s):  
Wiraporn Maithong ◽  
Chatchai Kruea-In ◽  
Somsawat Rattanasoon
Keyword(s):  
Binary System ◽  
Physical Properties ◽  
Orbital Period ◽  
Physical Parameters ◽  
Contact Binary

The physical parameters study of contact binary system AY Aquarius, the observations were done in 12th September 2011 at The Cerro Tololo Inter-American Observatory (CTIO), Chile. The Prompt4 0.4 - meter Ritchey-Chretien reflecting telescope and CCD Apogee Alta 10241024 pixels with standard visual and red filters of UBV were used. The orbital period of the contact binary system is about 0.28199 days. The photometry was analyzed by MaxIm program and used Wilson-Devinney technique to calculate the physical properties.

scholarly journals Apsidal motion in the massive binary HD 152248

2020 ◽  
Vol 642 ◽  
pp. A221
Author(s):  
S. Rosu ◽  
A. Noels ◽  
M.-A. Dupret ◽  
G. Rauw ◽  
M. Farnir ◽  
...  
Keyword(s):  
Binary System ◽  
Internal Structure ◽  
Turbulent Diffusion ◽  
Structure Constant ◽  
Orbital Plane ◽  
Apsidal Motion ◽  
Stellar Rotation ◽  
Single Star ◽  
Internal Mixing ◽  
The Impact

Context. Apsidal motion in massive eccentric binaries offers precious information about the internal structure of the stars. This is especially true for twin binaries consisting of two nearly identical stars. Aims. We make use of the tidally induced apsidal motion in the twin binary HD 152248 to infer constraints on the internal structure of the O7.5 III-II stars composing this system. Methods. We build stellar evolution models with the code Clés assuming different prescriptions for the internal mixing occurring inside the stars. We identify the models that best reproduce the observationally determined present-day properties of the components of HD 152248, as well as their internal structure constants, and the apsidal motion rate of the system. We analyse the impact on the results of some poorly constrained input parameters in the models, including overshooting, turbulent diffusion, and metallicity. We further build “single” and “binary” GENEC models that account for stellar rotation to investigate the impacts of binarity and rotation. We discuss some effects that could bias our interpretation of the apsidal motion in terms of the internal structure constant. Results. The analysis of the Clés models reveals that reproducing the observed k2 value and rate of apsidal motion simultaneously with the other stellar parameters requires a significant amount of internal mixing (either turbulent diffusion, overshooting, or rotational mixing) or enhanced mass-loss. The results obtained with the GENEC models suggest that a single-star evolution model is sufficient to describe the physics inside this binary system. We suggest that, qualitatively, the high turbulent diffusion required to reproduce the observations could be partly attributed to stellar rotation. We show that higher-order terms in the apsidal motion are negligible. Only a very severe misalignment of the rotation axes with respect to the normal to the orbital plane could significantly impact the rate of apsidal motion, but such a high misalignment is highly unlikely in such a binary system. Conclusions. We infer an age estimate of 5.15 ± 0.13 Myr for the binary system and initial masses of 32.8 ± 0.6 M⊙ for both stars.

Origin of Very-Short Orbital-Period Binary Systems

1983 ◽  
Vol 72 ◽  
pp. 263-267
Author(s):  
Shigeki Miyaji
Keyword(s):  
Binary System ◽  
Globular Cluster ◽  
Orbital Period ◽  
Binary Systems ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Close Binaries ◽  
X Ray ◽  
Evolutionary Scenario ◽  
Orbital Periods

Recent observations of four close binaries have established that there is a group of very-short orbital-period (VSOP) binaries whose orbital periods are less than 60 minutes. The VSOP binaries consist of both x-ray close binaries (4U1626-67; Middleditch et al. 1981 and 4U1916 -0.5; White and Swank 1982) and cataclysmic variables (AM CVn; Faulkner et al. 1972 and G61-29; Nather et al. 1981). Their orbital periods are too short to have a main-sequence companion. However, four binaries, none of them belongs to any globular cluster, are too abundant to be explained by capturing mechanism of a white dwarf. Therefore it seemed to be worth to present an evolutionary scenario from an original binary system which can be applied for all of VSOP binaries.

scholarly journals On the Internal Structure of Main-Sequence Stars

1982 ◽  
Vol 69 ◽  
pp. 37-46 ◽  
Author(s):  
Alvaro Giménez ◽  
José M. García-Pelayo
Keyword(s):  
Internal Structure ◽  
Strong Correlation ◽  
Main Sequence ◽  
Theoretical Models ◽  
Eclipsing Binaries ◽  
Main Sequence Stars ◽  
Structure Constants

We present the main results of a study of the observed internal structure constants, k2, for a wide set of eclipsing binaries. From the analysis of the variations in relative positions of the eclipses and the comparison with different theoretical models, we could deduce that the discrepancy, previously reported by several authors between theory and observations, is no longer supported. Moreover, a strong correlation has been found between the evolution of the parameter k2 and the gravity at the surface of the star, g.

scholarly journals The Origin of Millisecond Pulsar Velocities

1996 ◽  
Vol 160 ◽  
pp. 51-52
Author(s):  
Thomas M. Tauris
Keyword(s):  
Neutron Star ◽  
Binary System ◽  
Orbital Period ◽  
Main Sequence ◽  
Space Velocity ◽  
Computer Code ◽  
Millisecond Pulsar ◽  
Final State ◽  
Pulsar Velocity ◽  
Orbital Periods

We have developed a computer code (Tauris & Bailes 1996) to follow the evolution of a binary system from the zero-age main sequence to its “final” state as a binary millisecond pulsar (BMSP), at all stages keeping careful track of the mass and orbital separation of the two stars.To help determine the origin of millisecond pulsars, we compute the space velocities predicted by various models of their formation. It is difficult to produce a millisecond pulsar velocity greater than 270 km s−1with any model, unless the formation of the neutron star is accompanied by some form of asymmetric kick. We obtain average 3-D system velocities of 〈vrecoil〉= 99.6, 137.6 and 160.7 km s−1using Gaussian kicks of 〈vkick〉=0, 200 and 450 km s−1(σ=0, 100 and 200 km s - 1, respectively). Our computations show that, in general, we expect those systems with shorter orbital periods to have larger velocities than those with longer periods, but any relation between the final orbital period and space velocity is fairly weak, especially if asymmetries are involved.

scholarly journals The Wolf-Rayet Eclipsing Binary HD 5980 in the Small Magellanic Cloud

1982 ◽  
Vol 99 ◽  
pp. 317-320
Author(s):  
Jacques Breysacher ◽  
Anthony F. J. Moffat ◽  
Virpi S. Niemelä
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Orbital Period ◽  
Spectroscopic Data ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Eccentric Orbit ◽  
Eclipsing Binary ◽  
Hii Region ◽  
Rayet Star

The Wolf-Rayet star HD 5980, which is probably associated with the bright HII region NGC 346 of the Small Magellanic Cloud, was found to be an eclipsing binary by Hoffmann, Stift and Moffat (1978). Breysacher and Perrier (1980) determined the orbital period, P=19.266±0.003d, of the system whose light curve reveals a strongly eccentric orbit (e=0.47 for i=80°). The behaviour of the light curve outside the eclipses shows that we are dealing with a rather complex binary system. An analysis of the spectroscopic data is presented here.

scholarly journals HD 93795: a late-B supergiant star with a square circumstellar nebula

2019 ◽  
Vol 492 (2) ◽  
pp. 2383-2392 ◽  
Author(s):  
V V Gvaramadze ◽  
A Y Kniazev ◽  
N Castro ◽  
I Y Katkov
Keyword(s):  
Spectral Analysis ◽  
Binary System ◽  
Emission Line ◽  
Main Sequence ◽  
Stellar Atmosphere ◽  
Optical Spectra ◽  
Large Telescope ◽  
Space Telescope ◽  
Supergiant Star ◽  
First Time

ABSTRACT We report the discovery of a square axisymmetric circumstellar nebula around the emission-line star HD 93795 in the archival Spitzer Space Telescope 24 $\rm{\mu m}$ data. We classify HD 93795 as a B9 Ia star using optical spectra obtained with the Southern African Large Telescope (SALT). A spectral analysis carried out with the stellar atmosphere code fastwind indicates that HD 93795 only recently left the main sequence and is evolving redward for the first time. We discuss possible scenarios for the origin of the nebula and suggest that HD 93795 was originally a binary system and that the nebula was formed because of the merger of the binary components. We also discuss a discrepancy between distance estimates for HD 93795 based on the Gaia data and the possible membership of this star of the Car OB1 association, and conclude that HD 93795 could be at the same distance as Car OB1.

scholarly journals Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue

2019 ◽  
Vol 622 ◽  
pp. A114 ◽  
Author(s):  
K. G. Hełminiak ◽  
A. Tokovinin ◽  
E. Niemczura ◽  
R. Pawłaszek ◽  
K. Yanagisawa ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Main Sequence ◽  
Eclipsing Binaries ◽  
Spectroscopic Binaries ◽  
Physical Parameters ◽  
Centre Of Mass ◽  
Velocity Measurements ◽  
Spectroscopic Binary ◽  
Quadruple System ◽  
First Time

Aims. We present results of the combined photometric and spectroscopic analysis of three detached eclipsing binaries, the secondary components of which are not visible or are very hard to identify in the optical spectra – ASAS J052743–0359.7, ASAS J065134–2211.5, and ASAS J073507–0905.7. The first one is the known visual binary ADS 4022, and we found that it is a quadruple system composed of two spectroscopic binaries, one of which shows eclipses. None of the systems have previously been recognized as a spectroscopic binary. Methods. We used the following telescopes/spectrographs to collect a number of high-resolution optical and IR spectra: Subaru/IRCS, CTIO-1.5 m/CHIRON, Euler/CORALIE, MPG-2.2 m/FEROS, OAO-188/HIDES, and TNG/HARPS-N. We used these data to calculate radial velocities (RVs) and later combined them with MITSuME and ASAS photometry. The Subaru/IRCS IR spectra were crucial for secure identification of the lines of the cooler components. Radial velocity measurements were made with the TODCOR technique, and RV curves were modelled with our own procedure V2FIT. Light-curve modelling was performed with JKTEBOP and PHOEBE codes. Temperatures and metallicities of two systems were estimated from spectra. For the ADS 4022 system we also used the archival WDS data and new SOAR observations in order to derive the orbit of the visual pair for the first time. Ages were estimated by comparing our results with PARSEC isochrones. Results. The eclipsing pair ASAS J052743–0359.7 A (P = 5.27 d) is composed of a 1.03(6) M⊙, 1.03(2) R⊙ primary and a 0.60(2) M⊙, 0.59(2) R⊙ secondary. The components of the P = 21.57 d non-eclipsing pair B likely have masses in between the two eclipsing components, and both pairs are on a ∼188 yr orbit around their common centre of mass. The system ASAS J065134-2211.5 (P = 8.22 d) consists of a 0.956(12) M⊙, 0.997(4) R⊙ primary and a 0.674(5) M⊙, 0.690(7) R⊙ secondary. Finally, ASAS J073507-0905.7 (P = 1.45 d), which consists of a 1.452(34) M⊙, 1.635(12) R⊙ primary and a 0.808(13) M⊙, 0.819(11) R⊙ secondary, is likely a pre-main sequence system. In all cases secondary eclipses are total.

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