High resolution CoudeEchelle spectra of IX Per has been obtained at TÜBİTAK National Observatory... more High resolution CoudeEchelle spectra of IX Per has been obtained at TÜBİTAK National Observatory (TUG) of Turkey. IX Per has been known to be a single lined (SB1) spectroscopic binary having chromospheric activity. However, analyzed spectra of IX Per by KOREL disentangling ...
Evidence of secular dynamical evolution for detached active binary orbits are presented. First or... more Evidence of secular dynamical evolution for detached active binary orbits are presented. First order decreasing rates of orbital angular momentum (OAM), systemic mass ($M=M_{1}+M_{2}$) and orbital period of detached active binaries have been determined as $\dot J/J = -3.48 \times 10^{-10}$yr$^{-1}$, $\dot M/M = -1.30 \times 10^{-10}$yr$^{-1}$ and $\dot P/P = -3.96\times 10^{-10}$yr$^{-1}$ from the kinematical ages of 62 field detached systems. The ratio of $d \log J/ d \log M = 2.68$ implies that either there are mechanisms which amplify AM loss $\delta=2.68$ times with respect to isotropic AM loss of hypothetical isotropic winds or there exist external causes contributing AM loss in order to produce this mean rate of decrease for orbital periods. Various decreasing rates of OAM ($d \log J / dt$) and systemic mass ($d \log M/ dt$) determine various speeds of dynamical evolutions towards a contact configuration. According to average dynamical evolution with $\delta = 2.68$, the fract...
Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromosp... more Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of log Jo - log P, log M - log P and log Jo-log M were formed from 119 CAB and 102 W UMa stars. The log Jo-log M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log Jo - log M diagram. Since orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio q, the rates of orbital angular momentum loss (dlog Jo/dt) and mass loss (dlog M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log Jo - log M diagram. Evolution of q for a mass...
Monthly Notices of the Royal Astronomical Society, 2020
Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 syst... more Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 ≤ Z ≤ 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dust maps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes |b| ≤ 5° were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC–Teff relation, which is valid in the range 3100–36 000 K. De-reddened (B − V)0 colours, on the other hand, allowed us to calibrate two intrinsic colour–effective temperature relations; the linear one is valid...
Publications of the Astronomical Society of Australia, 2013
Physical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented... more Physical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented. Located at a distance of ~1.1 kpc from the Sun, the system was found to have two components with identical masses (M 1,2 = 1.92 M⊙), radii (R 1,2 = 1.76 R⊙), and luminosities (log L 1,2 = 1.1 L⊙) revolving in a circular orbit. Modeling the components with theoretical evolutionary tracks and isochrones implies a young age (t = 280 Myr) for the system, which is bigger than the synchronization time scale but smaller than the circularization time scale. Nevertheless, synthetic spectrum models revealed components’ rotation velocity of V rot12 = 70 km s−1, that is about three times higher than their synchronization velocity. No evidence is found for an age difference between the components.
A modelling of the sunspot deficit in solar irradiance measurements in 3 spectral wavelengths and... more A modelling of the sunspot deficit in solar irradiance measurements in 3 spectral wavelengths and the total flux as observed by the VIRGO experiment on SOHO has been performed for several periods of 1996 in a pixel-by-pixel manner using high resolution photoheliograms taken at Kanzelhöhe Observatory. The calculation of the irradiance contributions of the other features of active regions is
The last solar activity minimum in 1996 was characterized by several periods without any sunspots... more The last solar activity minimum in 1996 was characterized by several periods without any sunspots or faculae visible on the solar disk. Between these extremely quiet intervals, from time to time a single active region emerged and developed. The passage of these individual active regions across the visible solar hemisphere was accompanied by a pronounced variation in the solar irradiance
Publications of the Astronomical Society of Australia, 2014
The transformation equations from BVRc to g′r′i′ magnitudes and vice versa for the giants were es... more The transformation equations from BVRc to g′r′i′ magnitudes and vice versa for the giants were established from a sample of 80 stars collected from Soubiran et al. (2010) with confirmed surface gravity (2 ⩽ logg (cm s− 2) ⩽ 3) at effective temperatures 4000 < Teff (K) < 16000. The photometric observations, all sample stars at g′r′i′ and 65 of them at BVRc , were obtained at TÜBİTAK National Observatory (TUG) 1m (T100) telescope, on the Taurus Mountains in Turkey. The MV absolute magnitudes of the giant stars were estimated from the absolute magnitude-temperature data for the giant stars by Sung et al. (2013) using the Teff from the intrinsic colours considered in this study. The transformation equations could be considered to be valid through the ranges of the following magnitudes and colours involved: 7.10 < V 0 < 14.50, 7.30 < g′0…
High resolution CoudeEchelle spectra of IX Per has been obtained at TÜBİTAK National Observatory... more High resolution CoudeEchelle spectra of IX Per has been obtained at TÜBİTAK National Observatory (TUG) of Turkey. IX Per has been known to be a single lined (SB1) spectroscopic binary having chromospheric activity. However, analyzed spectra of IX Per by KOREL disentangling ...
Evidence of secular dynamical evolution for detached active binary orbits are presented. First or... more Evidence of secular dynamical evolution for detached active binary orbits are presented. First order decreasing rates of orbital angular momentum (OAM), systemic mass ($M=M_{1}+M_{2}$) and orbital period of detached active binaries have been determined as $\dot J/J = -3.48 \times 10^{-10}$yr$^{-1}$, $\dot M/M = -1.30 \times 10^{-10}$yr$^{-1}$ and $\dot P/P = -3.96\times 10^{-10}$yr$^{-1}$ from the kinematical ages of 62 field detached systems. The ratio of $d \log J/ d \log M = 2.68$ implies that either there are mechanisms which amplify AM loss $\delta=2.68$ times with respect to isotropic AM loss of hypothetical isotropic winds or there exist external causes contributing AM loss in order to produce this mean rate of decrease for orbital periods. Various decreasing rates of OAM ($d \log J / dt$) and systemic mass ($d \log M/ dt$) determine various speeds of dynamical evolutions towards a contact configuration. According to average dynamical evolution with $\delta = 2.68$, the fract...
Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromosp... more Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of log Jo - log P, log M - log P and log Jo-log M were formed from 119 CAB and 102 W UMa stars. The log Jo-log M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log Jo - log M diagram. Since orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio q, the rates of orbital angular momentum loss (dlog Jo/dt) and mass loss (dlog M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log Jo - log M diagram. Evolution of q for a mass...
Monthly Notices of the Royal Astronomical Society, 2020
Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 syst... more Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 ≤ Z ≤ 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dust maps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes |b| ≤ 5° were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC–Teff relation, which is valid in the range 3100–36 000 K. De-reddened (B − V)0 colours, on the other hand, allowed us to calibrate two intrinsic colour–effective temperature relations; the linear one is valid...
Publications of the Astronomical Society of Australia, 2013
Physical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented... more Physical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented. Located at a distance of ~1.1 kpc from the Sun, the system was found to have two components with identical masses (M 1,2 = 1.92 M⊙), radii (R 1,2 = 1.76 R⊙), and luminosities (log L 1,2 = 1.1 L⊙) revolving in a circular orbit. Modeling the components with theoretical evolutionary tracks and isochrones implies a young age (t = 280 Myr) for the system, which is bigger than the synchronization time scale but smaller than the circularization time scale. Nevertheless, synthetic spectrum models revealed components’ rotation velocity of V rot12 = 70 km s−1, that is about three times higher than their synchronization velocity. No evidence is found for an age difference between the components.
A modelling of the sunspot deficit in solar irradiance measurements in 3 spectral wavelengths and... more A modelling of the sunspot deficit in solar irradiance measurements in 3 spectral wavelengths and the total flux as observed by the VIRGO experiment on SOHO has been performed for several periods of 1996 in a pixel-by-pixel manner using high resolution photoheliograms taken at Kanzelhöhe Observatory. The calculation of the irradiance contributions of the other features of active regions is
The last solar activity minimum in 1996 was characterized by several periods without any sunspots... more The last solar activity minimum in 1996 was characterized by several periods without any sunspots or faculae visible on the solar disk. Between these extremely quiet intervals, from time to time a single active region emerged and developed. The passage of these individual active regions across the visible solar hemisphere was accompanied by a pronounced variation in the solar irradiance
Publications of the Astronomical Society of Australia, 2014
The transformation equations from BVRc to g′r′i′ magnitudes and vice versa for the giants were es... more The transformation equations from BVRc to g′r′i′ magnitudes and vice versa for the giants were established from a sample of 80 stars collected from Soubiran et al. (2010) with confirmed surface gravity (2 ⩽ logg (cm s− 2) ⩽ 3) at effective temperatures 4000 < Teff (K) < 16000. The photometric observations, all sample stars at g′r′i′ and 65 of them at BVRc , were obtained at TÜBİTAK National Observatory (TUG) 1m (T100) telescope, on the Taurus Mountains in Turkey. The MV absolute magnitudes of the giant stars were estimated from the absolute magnitude-temperature data for the giant stars by Sung et al. (2013) using the Teff from the intrinsic colours considered in this study. The transformation equations could be considered to be valid through the ranges of the following magnitudes and colours involved: 7.10 < V 0 < 14.50, 7.30 < g′0…
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