The Leadership Formula: P*M*D

Popper, Micha; Amit, Karin; Gal, Reuven; Mishkal-Sinai, Moran; Lisak, Alon

doi:10.21236/ada472601

Cited by 172 publications

(259 citation statements)

References 55 publications

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“…As pointed out by Popper (1998a), and also seen in Fig. 1 1 , AD Boo is of particular interest for having components with the greatest differences in mass and radius among well-studied binaries in its mass range.…”

Section: Introductionmentioning

confidence: 71%

“…1 1 , AD Boo is of particular interest for having components with the greatest differences in mass and radius among well-studied binaries in its mass range. Hence, it may provide stringent tests of stellar models, but the masses obtained in two recent analyses of the system disagree by slightly more than their stated errors (Lacy 1997a;Popper 1998a). Moreover, in both studies the radii were based on reanalyses of the relatively old B, V light curves (normal points) by Zhai et al (1982), which have an accuracy of only about 0.02 mag and show out-of-eclipse variations by about 0.075 mag.…”

Section: Introductionmentioning

confidence: 98%

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Absolute dimensions of eclipsing binaries. XXVI.

Clausen¹,

Torres

Bruntt

et al. 2008

A&A

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Context. Accurate mass, radius, and abundance determinations from binaries provide important information on stellar evolution, fundamental to central fields in modern astrophysics and cosmology. Aims. We aim to determine absolute dimensions and abundances for the three F-type main-sequence detached eclipsing binaries AD Boo, VZ Hya, and WZ Oph and to perform a detailed comparison with results from recent stellar evolutionary models. Methods. uvby light curves and uvbyβ standard photometry were obtained with the Strömgren Automatic Telescope at ESO, La Silla, radial velocity observations at CfA facilities, and supplementary high-resolution spectra with ESO's FEROS spectrograph. State-ofthe-art methods were applied for the analyses: the EBOP and Wilson-Devinney binary models, two-dimensional cross-correlation and disentangling, and the VWA abundance analysis tool. Results. Masses and radii that are precise to 0.5-0.7% and 0.4-0.9%, respectively, have been established for the components, which span the ranges of 1.1 to 1.4 M and 1.1 to 1.6 R . The [Fe/H] abundances are from -0.27 to +0.10, with uncertainties between 0.07 and 0.15 dex. We find indications of a slight α-element overabundance of [α/Fe] ∼ +0.1 for WZ Oph. The secondary component of AD Boo and both components of WZ Oph appear to be slightly active. Yale-Yonsai and Victoria-Regina evolutionary models fit the components of AD Boo and VZ Hya almost equally well, assuming coeval formation, at ages of about 1.75/1.50 Gyr (AD Boo) and 1.25/1.00 Gyr (VZ Hya). BaSTI models, however, predict somewhat different ages for the primary and secondary components. For WZ Oph, the models from all three grids are significantly hotter than observed. A low He content, decreased envelope convection coupled with surface activity, and/or higher interstellar absorption would remove the discrepancy, but its cause has not been definitively identified. Conclusions. We have demonstrated the power of testing and comparing recent stellar evolutionary models using eclipsing binaries, provided their abundances are known. The strongest limitations and challenges are set by T eff and interstellar absorption determinations, and by their effects on and correlation with abundance results.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 98%

Absolute dimensions of eclipsing binaries. XXVI.

Clausen¹,

Torres

Bruntt

et al. 2008

A&A

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“…Popper & Dumont (1977) obtained BV light curves at the Palomar and Kitt Peak observatories, which were later analysed by Popper & Etzel (1981). Preliminary absolute dimensions were included by Popper in his critical review of stellar masses (Popper 1980), and soon after he presented spectroscopic elements and improved absolute dimensions (Popper 1983). He reached component masses accurate to about 1% and radii accurate to 4% (primary) and 7% (secondary).…”

Section: Bk Pegmentioning

confidence: 99%

“…In order to perform abundance determinations and also improve the spectroscopic elements by Popper (1983), we have obtained 13 high-resolution (R = 45 000) spectra with the FIES fibre echelle spectrograph at Nordic Optical Telescope, La Palma during five consecutive nights in August 2007; see Table 3. For the basic reduction of the spectra, we have applied the IRAF based FIEStool package 2 .…”

Section: Spectroscopymentioning

confidence: 99%

“…Spectroscopic orbits have been derived from a re-analysis of the radial velocities by Popper (1983) and an analysis of the new radial velocities listed in Table 4. We have used the method of Lehman-Filhés implemented in the sbop 5 program (Etzel 2004), which is a modified and expanded version of an earlier code by Wolfe et al (1967).…”

Section: Spectroscopic Elementsmentioning

confidence: 99%

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Absolute dimensions of eclipsing binaries

Clausen¹,

Frandsen

Bruntt

et al. 2010

A&A

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Context. Double-lined, detached eclipsing binaries are our main source for accurate stellar masses and radii. In this paper we focus on the 1.15-1.70 M interval where convective core overshoot is gradually ramped up in theoretical evolutionary models. Aims. We aim to determine absolute dimensions and abundances for the F-type detached eclipsing binary BK Peg, and to perform a detailed comparison with results from recent stellar evolutionary models, including a sample of previously studied systems with accurate parameters. Methods. uvby light curves and uvbyβ standard photometry were obtained with the Strömgren Automatic Telescope, ESO, La Silla, and high-resolution spectra were acquired with the FIES spectrograph at the Nordic Optical Telescope, La Palma. Results. The 5. d 49 period orbit of BK Peg is slightly eccentric (e = 0.053). The two components are quite different with masses and radii of (1.414±0.007 M , 1.988±0.008 R ) and (1.257±0.005 M , 1.474±0.017 R ), respectively. The measured rotational velocities are 16.6 ± 0.2 (primary) and 13.4 ± 0.2 (secondary) km s −1 . For the secondary component this corresponds to (pseudo)synchronous rotation, whereas the primary component seems to rotate at a slightly lower rate. We derive an iron abundance of [Fe/H] = −0.12 ± 0.07 and similar abundances for Si, Ca, Sc, Ti, Cr and Ni. The stars have evolved to the upper half of the main-sequence band. YonseiYale and Victoria-Regina evolutionary models for the observed metal abundance reproduce BK Peg at ages of 2.75 and 2.50 Gyr, respectively, but tend to predict a lower age for the more massive primary component than for the secondary. We find the same age trend for three other upper main-sequence systems in a sample of well studied eclipsing binaries with components in the 1.15-1.70 M range. We also find that the Yonsei-Yale models systematically predict higher ages than the Victoria-Regina models. The sample includes BW Aqr, and as a supplement we have determined a [Fe/H] abundance of −0.07 ± 0.11 for this late F-type binary. Conclusions. We propose to use BK Peg, BW Aqr, and other well-studied 1.15-1.70 M eclipsing binaries to fine-tune convective core overshoot, diffusion, and possibly other ingredients of modern theoretical evolutionary models.

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One of the first members of RS CVn‐type systems: MM Herculis

Taș¹,

Evren²

2013

Astron Nachr

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We present the long-term multi-colour photometry of MM Her which is one of the first members of the RS CVn-type of eclipsing binary systems. We took advantage of its photometry-spanning 33 years to evaluate its long-term variation, which is caused by the evolution of the activity structures located on the surface of the cooler component. In this study we found that the long-term variation in the brightness, colour, and amplitude of seasonal light curves over the years could be represented by two periods: one of which is of around 22.5 years, and is similar to all in this regard, but the other is a period value of about 9.5 years for the brightness variation, and of about 7.5 years for the variation in colour and amplitude. The analysis of the spot minimum phases gives a migration period of approximately 7.8 years. We also presented a new light curve analysis solution, and improved its light elements in this study.

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The Leadership Formula: PMD

Cited by 172 publications

References 55 publications

Absolute dimensions of eclipsing binaries. XXVI.

Absolute dimensions of eclipsing binaries. XXVI.

Absolute dimensions of eclipsing binaries

One of the first members of RS CVn‐type systems: MM Herculis

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