Towards a Network of Faint DA White Dwarfs as High-Precision Spectrophotometric Standards

TL;DR

This paper proposes establishing a network of faint DA white dwarfs as high-precision spectrophotometric standards to support wide-field surveys, demonstrating initial success and methodological robustness.

Contribution

It introduces a new network of faint DA white dwarfs as spectrophotometric standards, with methods for modeling and calibration applicable across multiple observatories and instruments.

Findings

Successful initial modeling of white dwarf spectra

Equivalent results from different modeling approaches

Practical framework for establishing standard star network

Abstract

We present initial results from a program aimed at establishing a network of hot DA white dwarfs to serve as spectrophotometric standards for present and future wide-field surveys. These stars span the equatorial zone and are faint enough to be conveniently observed throughout the year with large-aperture telescopes. Spectra of these white dwarfs are analyzed to generate a non-local-thermodynamic-equilibrium (NLTE) model atmosphere normalized to HST colors, including adjustments for wavelength-dependent interstellar extinction. Once established, this standard star network will serve ground-based observatories in both hemispheres as well as space-based instrumentation from the UV to the near IR. We demonstrate the effectiveness of this concept and show how two different approaches to the problem using somewhat different assumptions produce equivalent results. We discuss lessons learned and the resulting corrective actions applied to our program.