A near-IR spectrum of the DO white dwarf RE J0503-285

P D Dobbie,A J Levan,I Hubeny,R Napiwotzki,M A Barstow,M R Burleigh

doi:10.1051/0004-6361:20053215

P D Dobbie, A J Levan + Show 4 more

Open Access

https://doi.org/10.1051/0004-6361:20053215

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Abstract

We present a near-IR spectroscopic analysis of the intriguing DO white dwarf RE J0503-285. The IR spectrum fails to reveal evidence of the presence of a spatially unresolved, cool, late-type companion. Hence we have placed an approximate limit on the spectral-type and mass of a putative companion (later than M8, ). This result rules out ongoing interaction between the white dwarf and a close companion with as responsible for the discrepancies between the observed photospheric abundances and model predictions. As the possibility remains that there is a cooler companion lying beyond the detection threshold of this study we use our modelling to estimate the improvement in sensitivity offered by a Spitzer observation.

Highlights

In accord with a theoretical prediction made several decades ago (Schatzman 1958), the atmospheres of white dwarfs are observed to be dominated either by hydrogen (DAs) or by helium (DO/DBs)
If a thermal pulse occurs as the star evolves off the AGB, much of the remaining hydrogen is incinerated and nuclear processed material from deeper layers (e.g. C and O) is dredged up to the surface leading to a hydrogen deficient object (e.g. Iben et al 1983; Herwig et al 1999)
The flux levels of the data were scaled to (1) achieve the best possible agreement between the blue and the red spectrum of the white dwarf in the overlap region between 1.53−1.64 μm and (2) obtain the best possible agreement between the spectral data and the J, H and KS photometric fluxes for RE J0503-285 derived from the 2MASS All Sky Data Release Point Source Catalogue magnitudes (Skrutskie et al 1997) where zero magnitude fluxes were taken from Zombeck (1990)

Summary

Introduction

In accord with a theoretical prediction made several decades ago (Schatzman 1958), the atmospheres of white dwarfs are observed to be dominated either by hydrogen (DAs) or by helium (DO/DBs). No convincing evidence of the presence of iron is found in any of the spectral datasets obtained to date, setting an upper limit on its abundance of Fe/H

Data acquisition

Data reduction

Model DO white dwarf spectra

The search for a cool companion

A limit on the mass of a pututive companion to RE J0503-285

Possible future work