scholarly journals Fundamental properties of the pre-main sequence eclipsing stars of MML 53 and the mass of the tertiary

2019 ◽  
Vol 623 ◽  
pp. A23 ◽  
Author(s):  
Y. Gómez Maqueo Chew ◽  
L. Hebb ◽  
H. C. Stempels ◽  
A. Paat ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Close Binary ◽  
Formation Mechanisms ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Secondary Star ◽  
The Third ◽  
Eclipsing Stars ◽  
Systemic Velocity ◽  
Outer Component ◽  
The Masses

We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (with PEB = 2.097892 d), and for the first time, confirm the bound-nature of the third star (in a P3 ∼ 9 yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880 ± 100 K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M1 = 1.0400 ± 0.0067 M⊙ and M2 = 0.8907 ± 0.0058 M⊙), their radii within 4.5% (R1 = 1.283 ± 0.043 R⊙ and R2 = 1.107 ± 0.049 R⊙), and the temperature of the secondary star (Teff, 2 = 4379 ± 100 K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7 M⊙ (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16 ± 2 Myr). At this age, the tightening of the MML 53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars’ evolution. The eclipsing components of MML 53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04 M⊙ primary star of MML 53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsing stars of MML 53 are found to be larger but not cooler than predicted by non-magnetic models, it is not clear what is the mechanism that is causing the radius inflation given that activity, spots and/or magnetic fields slowing their contraction, require the inflated stars to be cooler to remain in thermal equilibrium.

scholarly journals Fundamental properties of the pre-main sequence eclipsing stars of MML 53 and the mass of the tertiary

2019 ◽  
Vol 623 ◽  
pp. A23
Author(s):  
Y. Gómez Maqueo Chew ◽  
L. Hebb ◽  
H. C. Stempels ◽  
A. Paat ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Close Binary ◽  
Formation Mechanisms ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Secondary Star ◽  
The Third ◽  
Eclipsing Stars ◽  
Systemic Velocity ◽  
Outer Component ◽  
The Masses

We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (with PEB = 2.097892 d), and for the first time, confirm the bound-nature of the third star (in a P3 ∼ 9 yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880 ± 100 K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M1 = 1.0400 ± 0.0067 M⊙ and M2 = 0.8907 ± 0.0058 M⊙), their radii within 4.5% (R1 = 1.283 ± 0.043 R⊙ and R2 = 1.107 ± 0.049 R⊙), and the temperature of the secondary star (Teff, 2 = 4379 ± 100 K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7 M⊙ (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16 ± 2 Myr). At this age, the tightening of the MML 53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars’ evolution. The eclipsing components of MML 53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04 M⊙ primary star of MML 53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsing stars of MML 53 are found to be larger but not cooler than predicted by non-magnetic models, it is not clear what is the mechanism that is causing the radius inflation given that activity, spots and/or magnetic fields slowing their contraction, require the inflated stars to be cooler to remain in thermal equilibrium.

scholarly journals The Eclipses of the Close Binary Star BE UMa

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.

scholarly journals The single-sided pulsator CO Camelopardalis

2020 ◽  
Vol 494 (4) ◽  
pp. 5118-5133 ◽  
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.

scholarly journals WASP 0639-32: a new F-type subgiant/K-type main-sequence detached eclipsing binary from the WASP project

2018 ◽  
Vol 615 ◽  
pp. A135 ◽  
Author(s):  
J. A. Kirkby-Kent ◽  
P. F. L. Maxted ◽  
A. M. Serenelli ◽  
D. R. Anderson ◽  
C. Hellier ◽  
...  
Keyword(s):  
Binary System ◽  
Main Sequence ◽  
Mass Density ◽  
Helium Abundance ◽  
Eclipsing Binary ◽  
Abundance Estimate ◽  
Secondary Star ◽  
Free Parameters ◽  
Effective Temperatures ◽  
The Masses

Aims. Our aim is to measure the masses and radii of the stars in a newly-discovered detached eclipsing binary system to a high precision (≈1%), enabling the system to be used for the calibration of free parameters in stellar evolutionary models. Methods. Photometry from the Wide Angle Search for Planets (WASP) project was used to identify 1SWASP J063930.33-322404.8 (TYC 7091-888-1, WASP 0369-32 hereafter) as a detached eclipsing binary system with total eclipses and an orbital period of P = 11.66 days. Lightcurve parameters for WASP 0639-32 are obtained using the EBOP lightcurve model, with standard errors evaluated using a prayer-bead algorithm. Radial velocities were measured from 11 high-resolution spectra using a broadening function approach, and an orbit was fitted using SBOP. Observed spectra were disentangled and an equivalent width fitting method was used to obtain effective temperatures and metallicities for both stars. A Bayesian framework is used to explore a grid of stellar evolution models, where both helium abundance and mixing length are free to vary, and use observed parameters (mass, density, temperature, and metallicity) for each star to obtain the age and constrain the helium abundance of the system. Results. The masses and radii are found to be M1 = 1.1544 ± 0.0043 M⊙, R1 = 1.833 ± 0.023 R⊙, and M2 = 0.7833 ± 0.0028 M⊙, R2 = 0.7286 ± 0.0081 R⊙ for the primary and secondary, respectively. The effective temperatures were found to be T1 = 6330 ± 50 K and T2 = 5400 ± 80 K for the primary and secondary star, respectively. The system has an age of 4.2−0.1+0.8 Gyr, and a helium abundance in the range 0.251–0.271. Conclusions. WASP 0639-32 is a rare example of a well-characterised detached eclipsing binary system containing a star near the main-sequence turn-off point. This makes it possible to measure a precise age for the stars in this binary system and to estimate their helium abundance. Further work is needed to explore how this helium abundance estimate depends on other free parameters in the stellar models.

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.

scholarly journals On rare core collapse supernovae inside planetary nebulae

2020 ◽  
Vol 500 (3) ◽  
pp. 2850-2858
Author(s):  
Ealeal Bear ◽  
Noam Soker
Keyword(s):  
Mass Transfer ◽  
Binary System ◽  
Equal Mass ◽  
Core Collapse ◽  
Primary Star ◽  
Core Collapse Supernova ◽  
Secondary Star ◽  
The Third ◽  
Time Period ◽  
Binary Evolution

ABSTRACT We conduct simulations using mesa of the reverse formation of a white dwarf (WD)–neutron star (NS) binary system in which the WD forms before the NS. We conclude that a core collapse supernova (CCSN) explosion might occur inside a planetary nebula (PN) only if a third star forms the PN. In this WD–NS reverse binary evolution, the primary star evolves and transfers mass to the secondary star, forms a PN, and leaves a WD remnant. If the mass-transfer brings the secondary star to have a mass of $\gtrsim 8\, \mathrm{ M}_\odot$ before it develops a helium core, and if the secondary does not suffer an enhanced mass-loss before it develops a massive helium core, e.g. by mass-transfer, it explodes as a CCSN and leaves an NS remnant. The time period from the formation of the PN by the primary to the explosion of the secondary is $\gtrsim 10^6 {~\rm yr}$. By that time, the PN has long dispersed into the interstellar medium. In a binary system with nearly equal-mass components, the first mass-transfer episode takes place after the secondary star has developed a helium core and it ends its life forming a PN and a WD. The formation of a CCSN inside a PN (CCSNIP) requires the presence of a third star. The third star should be less massive than the secondary star but by no more than few ×0.01 M⊙. We estimate that the rate of CCSNIP is ≈10−4 times the rate of all CCSNe.

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.

150 Years of Das Kapital and No End in Sight. Unsystematic Remarks on a Never-Ending Story

2019 ◽  
Vol 29 (6) ◽  
pp. 23-46
Keyword(s):  
Political Economy ◽  
Formal Structure ◽  
Monetary Theory ◽  
Economic Crises ◽  
General Introduction ◽  
The Third ◽  
Social Forms ◽  
Adequate Understanding ◽  
Theory Of Value ◽  
The Masses

Michael Heinrich, one of the leading Marx scholars, provides a general introduction into Das Kapital with emphasis on the latest interpretations of it. The circumstances surrounding its writing and publication are shown to have interfered with an adequate appreciation of it. The formal structure and organization of the first volume are obstacles to readers and demand much from their education and intellect. The article summarizes the basic trajectories of Marx’s criticisms of political economy, including the critique of naturalizing social forms arising under capitalism and Marx’s original monetary theory of value. The author disentangles Marx’s Das Kapital from views mistakenly ascribed to it, such as the idea that value is determined solely by labor and the prediction of pauperization of the masses. First, Marx’s theory of value goes well beyond explaining prices under capitalism. Second, his main prophecy concerned the inevitable growth of inequality between the masters of capital and the employed classes and did not forecast impoverishment. The paper also points out that the sequence of publication of different volumes of Das Kapital caused lacunae in interpreting Marx’s oeuvre. For instance Engels’ efforts made the third volume more accessible to readers but also obscured the overall pattern of Marx’s thinking. the article shows that Das Kapital was a dynamic and fluctuating project to such an extent that Marx himself several times revisited his views of the causes of economic crises and falling profits and also intended to deal extensively with ecological issues. Reaching an adequate understanding of the theory contained in Das Kapital cannot depend on the manuscripts of those volumes alone. Marx’s notebooks, which have only recently published, are an indispensable aid to understanding it.

scholarly journals X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

2018 ◽  
Vol 619 ◽  
pp. A138
Author(s):  
V. Perdelwitz ◽  
S. Czesla ◽  
J. Robrade ◽  
T. Pribulla ◽  
J. H. M. M. Schmitt
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Binary Systems ◽  
Uv Light ◽  
Close Binary ◽  
Eclipsing Binary ◽  
X Ray ◽  
Uv Emission ◽  
Low Mass ◽  
Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

scholarly journals Long-Term Variability and Outburst Activity of FS Aurigae: Further Evidence for a Third Body in the System

2011 ◽  
Vol 7 (S282) ◽  
pp. 79-80
Author(s):  
V. Neustroev ◽  
G. Sjoberg ◽  
G. Tovmassian ◽  
S. Zharikov ◽  
T. Arranz Heras ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Close Binary ◽  
Third Body ◽  
Secondary Star ◽  
Long Term Monitoring ◽  
Binary Orbit ◽  
Term Monitoring

AbstractFS Aurigae is famous for a variety of uncommon and puzzling periodic photometric and spectroscopic variabilities which do not fit well into any of the established sub-classes of cataclysmic variables. Here we present preliminary results of long-term monitoring of the system, conducted during the 2010-2011 observational season. We show that the long-term variability of FS Aur and the character of its outburst activity may be caused by variations in the mass transfer rate from the secondary star as the result of eccentricity modulation of a close binary orbit induced by the presence of a third body on a circumbinary orbit.

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