Spectral energy distributions and colours of hot subluminous stars

TL;DR

This paper demonstrates how to construct and analyze spectral energy distributions and colours of hot subluminous B stars to identify companions and determine atmospheric parameters, leveraging multi-wavelength photometric data.

Contribution

It introduces a methodology for using spectral energy distributions and colours to study hot subdwarf stars and their companions, with applications to large survey data.

Findings

Analyzed two benchmark sdB stars with high-quality data.

Presented preliminary results for 142 sdB binaries.

Discussed future prospects with ongoing all-sky surveys.

Abstract

Photometric surveys at optical, ultraviolet, and infrared wavelengths provide ever growing datasets as major surveys proceed. Colour-colour diagrams are useful tools to identify classes of stars and to provide large samples. Combining all photometric measurements of a star into a spectral energy distribution will allow quantitative analyses to be carried out. We demonstrate how to construct and exploit spectral energy distributions and colours for sublumious B (sdB) stars. The aim is to identify cool companions to hot subdwarfs and to determine atmospheric parameters of apparently single sdB stars as well as composite spectrum sdB binaries. We analyse two sdB stars with high-quality photometric data which serve as our benchmarks, the apparently single sdB HD 205805 and the sdB + K5 binary PG 0749+658, briefly present preliminary results for the sample of 142 sdB binaries with known orbits, and discuss future prospects from ongoing all-sky optical space- (Gaia) and ground-based (e.g. SkyMapper) as well as NIR surveys.