Scientists found 3 pre-white dwarfs (WDs) with helium-dominated atmospheres.
They calculated the effective temperature and surface gravity by comparing the He II line profiles of different stars.
Tübingen Model-Atmosphere Package tool was used for spectral analysis and to compute nonlocal thermodynamic equilibrium, plane-parallel, line-blanketed atmosphere models in radiative and hydrostatic equilibrium. It is based on the Accelerated Lambda Iteration method.
Kiel (Teff– log(g)) diagram was used to analyse the stars. The masses of stars were determined via comparison with evolutionary tracks using linear interpolation or Extrapolation and use of very late thermal pulse (VLTP)- a stage of evolution that occurs when a star re-ignites helium after leaving the Asymptotic Giant Branch (AGB) and still has a hydrogen-burning shell. By using these parameters, stellar radii was calculated by,
Luminosity was calculated by,
Gaia parallax distances can be used to derive masses, radii, and luminosities.
They used a spectral energy distribution (SED) graph that shows how much energy a star emits at different wavelengths. It's usually represented as luminosity per unit wavelength or frequency.
Source:
https://arxiv.org/html/2412.15984v1
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