Main-Sequence Effective Temperatures From a Revised Mass–luminosity Relation Based on Accurate Properties

Abstract

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 ...

What Sets the Radial Locations of Warm Debris Disks?

“…McDonald et al (2012) assumed a 10% uncertainty on the photometry they used to derive L å , so we also assumed a 10% uncertainty on L å . Combining this with the intrinsic 25%-38% scatter in the L å values Eker et al (2015) used to derive their relations yields a ∼6%-10% uncertainty on our M å values. For the targets not listed in McDonald et al (2012; denoted with an "a" after the target name in Table 1), we inferred their stellar properties from their V K -color using the tabulated values maintained online 3 by E. Mamajek as an expanded and updated version of Table5 in Pecaut and Mamajek (2013).…”

“…We then obtained the stellar mass (M å ) from L å using the (broken) power-law relation by Eker et al (2015). McDonald et al (2012) assumed a 10% uncertainty on the photometry they used to derive L å , so we also assumed a 10% uncertainty on L å .…”

A Hot Companion to a Blue Straggler in NGC 188 as Revealed by the Ultra-Violet Imaging Telescope (Uvit) on Astrosat

“…We estimated the radii of the component stars, using the relation R/R = (T /T ) 2 (L/L ) (0.5) , the luminosity is estimated from the absolute magnitude, bolometric correction and a distance of 2kpc. For the BSS, we also estimated the Luminosity using the relation given in table 3 of Eker et al (2015) and Padova models. The BSS is found to have a radius of ∼ 1.1 -1.6R , and the Luminosity of ∼ 1.4 -2.8L , whereas the hot component is found to have a radius of ∼ 0.6R , and a Luminosity of ∼ 30L .…”

Optical–infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

“…Note that ξ * is of order unity for main sequence stars with M * 2M ⊙ (e.g., Torres et al 2010;Eker et al 2015).…”