Absolute parameters of 509 main-sequence stars selected from the components of detached-eclipsing spectroscopic binaries in the Solar neighbourhood are used to study mass-luminosity, mass-radius and mass-effective temperature relations (MLR, MRR and MTR). The MLR function is found better if expressed by a six-piece classical MLR (L ∝ M α ) rather than a fifth or a sixth degree polynomial within the mass range of 0.179 M/M ⊙ 31. The break points separating the mass-ranges with classical MLR do not appear to us to be arbitrary. Instead, the data indicate abrupt changes along the mass axis in the mean energy generation per unit of stellar mass. Unlike the MLR function, the MRR and MTR functions cannot be determined over the full range of masses. A single piece MRR function is calibrated from the radii of stars with M 1.5M ⊙ , while a second single piece MTR function is found for stars with M > 1.5M ⊙ . The missing part of the MRR is computed from the MLR and MTR, while the missing part of the MTR is computed from the MLR and MRR. As a result, we have interrelated MLR, MRR and MTR, which are useful in determining the typical absolute physical parameters of main-sequence stars of given masses. These functions are also useful to esc The Authors 2 Eker et al. timate typical absolute physical parameters from typical T ef f values. Thus, we were able to estimate the typical absolute physical parameters of mainsequence stars observed in the Sejong Open Cluster survey, based on that survey's published values for T ef f . Since typical absolute physical parameters of main sequence stars cannot normally be determined in such photometric surveys, the interrelated functions are shown to be useful to compute such missing parameters from similar surveys.
The mass-luminosity (M − L), mass-radius (M − R) and mass-effective temperature (M − T ef f ) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to ≤ 3% and luminosities accurate to ≤ 30% (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7M ⊙ within the mass range studied of 0.38 − 32M ⊙ . Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical (L ∝ M α ), are shown to be preferable to a single linear, quadratic or cubic equation representing as an alternative MLR. Stellar radius evolution within the main-sequence for stars with M > 1M ⊙ is clearly evident on the M − R diagram, but it is not the clear on the M − T ef f diagram based on published temperatures. Effective temperatures can be calculated directly using the well-known Stephan-Boltzmann law by employing the accurately known values of M and R with the newly defined MLRs. With the calculated temperatures, stellar temperature evolution within the main-sequence for stars with M > 1M ⊙ is clearly visible on the M − T ef f diagram.Our study asserts that it is now possible to compute the effective temperature of a mainsequence star with an accuracy of ∼ 6%, as long as its observed radius error is adequately small (< 1%) and its observed mass error is reasonably small (< 6%).A calibration sample was formed by selecting main-sequence stars with the most accurate masses, radii and effective temperatures from Table 2 of "The Catalogue of Stellar Parameters ..." by Eker et al. (2014), which is already reprocessed and homogenized. In the first step, our preliminary criteria involved finding stars where both mass and radius with errors of less than or equal to 3%, and luminosities with errors less than or equal to 30% were available. Among 514 stars (257 binaries), 296 stars were found fulfilling the criteria.In the second step, 25 stars outside of the main sequence were removed.The process of removing non-main-sequence stars was completed by using the mass-radius diagram. Compared to effective temperatures and luminosities, which can only be inferred indirectly, masses and radii provide much more reliable indicators of stellar properties, and a highly improved diagnostic tool for analyzing stellar evolution. Fig. 1 shows 271 main-sequence stars selected for the calibration sample and 25 non main-sequence stars on the M − R diagram. Theoretical ZAMS (Zero Age Main Sequence) and TAMS (Terminal Age Main Sequence) lines for metallicity zero from Bertelli et al. (2008Bertelli et al. ( , 2009 were used as border lines to secure the stars within the main-sequence band.Although metallicity data is missing in the catalogue of Eker et al. (2014), the thin-disk field stars in ...
We study the kinematics of 129 W UMa binaries and we discuss its implications on the contact binary evolution. The sample is found to be heterogeneous in the velocity space. That is, kinematically younger and older contact binaries exist in the sample. A kinematically young (0.5 Gyr) subsample (moving group) is formed by selecting the systems that satisfy the kinematical criteria of moving groups. After removing the possible moving group members and the systems that are known to be members of open clusters, the rest of the sample is called the field contact binary (FCB) group. The FCB group is further divided into four groups according to the orbital period ranges. Then, a correlation is found in the sense that shorter‐period less‐massive systems have larger velocity dispersions than the longer‐period more‐massive systems. Dispersions in the velocity space indicate a 5.47‐Gyr kinematical age for the FCB group. Compared with the field chromospherically active binaries (CABs), presumably detached binary progenitors of the contact systems, the FCB group appears to be 1.61 Gyr older. Assuming an equilibrium in the formation and destruction of CAB and W UMa systems in the Galaxy, this age difference is treated as an empirically deduced lifetime of the contact stage. Because the kinematical ages (3.21, 3.51, 7.14 and 8.89 Gyr) of the four subgroups of the FCB group are much longer than the 1.61‐Gyr lifetime of the contact stage, the pre‐contact stages of the FCB group must dominantly be producing the large dispersions. The kinematically young (0.5 Gyr) moving group covers the same total mass, period and spectral ranges as the FCB group. However, the very young age of this group does not leave enough room for pre‐contact stages, and thus it is most likely that these systems were formed in the beginning of the main sequence or during the pre‐main‐sequence contraction phase, either by a fission process or most probably by fast spiralling in of two components in a common envelope.
The catalogue of chromospherically active binaries (CABs) has been revised and updated. With 203 new identifications, the number of CAB stars is increased to 409. The catalogue is available in electronic format where each system has a number of lines (suborders) with a unique order number. The columns contain data of limited numbers of selected cross references, comments to explain peculiarities and the position of the binarity in case it belongs to a multiple system, classical identifications (RS Canum Venaticorum, BY Draconis), brightness and colours, photometric and spectroscopic data, a description of emission features (Ca II H and K, H α , ultraviolet, infrared), X-ray luminosity, radio flux, physical quantities and orbital information, where each basic entry is referenced so users can go to the original sources.
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