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 ...

Estimates of galaxy distances based on indicators that are independent of cosmological redshift are fundamental to astrophysics. Researchers use them to establish the extragalactic distance scale, to underpin estimates of the Hubble constant, and to study peculiar velocities induced by gravitational attractions that perturb the motions of galaxies with respect to the "Hubble flow" of universal expansion. In 2006 the NASA/IPAC Extragalactic Database (NED) began making available a comprehensive compilation of redshift-independent extragalactic distance estimates. A decade later, this compendium of distances (NED-D) now contains more than 100,000 individual estimates based on primary and secondary indicators, available for more than 28,000 galaxies, and compiled from over 2000 references in the refereed astronomical literature. This paper describes the methodology, content, and use of NED-D, and addresses challenges to be overcome in compiling such distances. Currently, 75 different distance indicators are in use. We include a figure that facilitates comparison of the indicators with significant numbers of estimates in terms of the minimum, 25th percentile, median, 75th percentile, and maximum distances spanned. Brief descriptions of the indicators, including examples of their use in the database, are given in an appendix.

Numerous research topics rely on an improved cosmic distance scale (e.g., cosmology, gravitational waves) and the NASA/IPAC Extragalactic Database of Distances (NED-D) supports those efforts by tabulating multiple redshift-independent distances for 12,000 galaxies (e.g., Large Magellanic Cloud (LMC) zero-point). Six methods for securing a mean estimate distance (MED) from the data are presented (e.g., indicator and Decision Tree). All six MEDs yield surprisingly consistent distances for the cases examined, including for the key benchmark LMC and M106 galaxies. The results underscore the utility of the NED-D MEDs in bolstering the cosmic distance scale and facilitating the identification of systematic trends.

Using SDSS DR15 to its full extent, we derived fundamental plane distances to over 317 000 early-type galaxies up to a redshift of 0.4. In addition to providing the largest sample of fundamental plane distances ever calculated, as well as a well calibrated group catalogue covering the entire SDSS spectroscopic footprint as far a redshift of 0.5, we present several improvements reaching beyond the traditional definition of the fundamental plane. In one approach, we adjusted the distances by removing systematic biases and selection effects in redshift-magnitude space, thereby greatly improving the quality of measurements. Alternatively, by expanding the traditional fundamental plane by additional terms, we managed to remove systematic biases caused by the selection of our SDSS spectroscopic galaxy sample as well as notably reducing its scatter. We discuss the advantages and caveats of these various methods and calibrations in detail. We found that improving the fundamental plane distance estimates beyond the established methods requires a delicate balancing act between various systematic biases and gains, but managed to reduce the uncertainty of our distance measurements by about a factor of two compared to the traditional fundamental plane.

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EU scientific visa is a success in Ireland From experience in Ireland, I contend that Europe's scientific visa and the EURAXESS services can solve most of the Who discovered Universe expansion?

In this study, the distributions of the double-lined detached binaries (DBs) on the planes of mass-luminosity, mass radius and mass-effective temperature have been studied. We improved the classical mass-luminosity relation based on the database of DBs by Eker et al. (2004a). With accurate observational data available to us, a method for improving effective temperatures for eclipsing binaries with accurate masses and radii were suggested.