Physical Parameters of W UMa Type Contact Binaries and Their Stability of Mass Transfer

In this study,we determined the physical parameters of W UMa type contact binaries and their stability of mass transfer with different stellar mass ranges over a broad space by applying the basic dynamical evolution equations of the W UMa type contact binaries using accretor and donor masses between 0.079 and 2.79 M_(⊙).In these systems,we have studied the three subclasses of W UMa systems of A-,B-and W-type contact binaries using the initial and final mass ranges and we investigated different stellar and orbital parameters for the subclasses of W UMa systems.We examined the stability of the W UMa type contact binaries using the orbital parameters such as critical mass ratio,Roche lobe radius of the donor star and mass ratio of these systems.Thus,we computed the observed and calculated physical parameters of A-,B-and W-type W UMa systems.Moreover,we determined the combined and color temperatures to classify the three subclasses of the systems.Also,we presented the result of the internal stellar structure and evolution of W UMa type contact binaries by using the polytropic model.

Photometric Properties and Stellar Parameters of the Rapidly Rotating Magnetic Early-B Star HD 345439

We first present the multicolor photometry results of the rapidly rotating magnetic star HD 345439 using the Nanshan One-meter Wide-field Telescope.From the photometric observations,we derive a rotational period of 0.7699±0.0014 day.The light curves of HD 345439 are dominated by the double asymmetric S-wave feature that arises from the magnetic clouds.Pulsating behaviors are not observed in Sector 41 of the Transiting Exoplanet Survey Satellite.No evidence is found of the occurrence of centrifugal breakout events neither in the residual flux nor in the systematic variations at the extremum of the light curve.Based on the hypothesis of the Rigidly Rotating Magnetosphere model,we restrict the magnetic obliquity angleβand the rotational inclination angle i so that they satisfy the approximate relationβ+i≈105°.The color excess,extinction,and luminosity are determined to be E_((B-V))=0.745±0.016 mag,A_(V)=2.31±0.05 mag,and log(L/L_(⊙))=3.82±0.1 dex,respectively.Furthermore,we derive the effective temperature as T_(eff)=22±1 kK and the surface gravity as log g=4.00±0.22.The mass M=-7.24_(-1.24)^(+1.75)M_(⊙),radius R=4.44_(-1.93)^(+2.68)R_(⊙),and age τ_(age)=23.62_(-21.97)^(+4.24) Myr are estimated from the Hertzsprung-Russell diagram.

A Catalog and Statistical Analysis for Magnetic Stars

Magnetic fields are significant in the structure and evolution of stars. We present a comprehensive catalog of 1784known magnetic stars, detailing their identifications, HD numbers, precise locations, spectral types and averaged quadratic effective magnetic fields among other important information. The group comprises 177 O-type stars, 551B-type stars, 520 A-type stars, 91 F-type stars, 53 G-type stars, 61 K-type stars, 31 M-type stars and an additional300 stars whose spectral classification remains indeterminate. Our analysis examines the statistical properties of these magnetic stars. The relative integrated distribution function and number distribution function for all magnetic stars of the same spectral type can be effectively approximated using an exponential function of the averaged quadratic effective magnetic field. The analysis further reveals that A and B-type stars possess the strongest mean magnetic fields, indicating an easier detection of their magnetic fields.