Iras-allsky

Serendipitous discovery of a dusty disc around WDJ181417.84-735459.83

March 2021 • 2021MNRAS.501.3916G

Authors • Gonz├ílez Egea, E. • Raddi, R. • Koester, D. • Rogers, L. K. • Marocco, F. • Cooper, W. J. • Beamin, J. C. • Burningham, B. • Day-Jones, A. • Forbrich, J. • Pinfield, D. J.

Abstract • Spectroscopic observations of white dwarfs reveal that many of them are polluted by exoplanetary material, whose bulk composition can be uniquely probed this way. We present a spectroscopic and photometric analysis of the DA white dwarf WDJ181417.84-735459.83, an object originally identified to have a strong infrared (IR) excess in the 2MASS and WISE catalogues that we confirmed to be intrinsic to the white dwarf, and likely corresponding to the emission of a dusty disc around the star. The finding of Ca, Fe, and Mg absorption lines in two X-SHOOTER spectra of the white dwarf, taken 8 years apart, is further evidence of accretion from a dusty disc. We do not report variability in the absorption lines between these two spectra. Fitting a blackbody model to the IR excess gives a temperature of 910 ┬▒ 50 K. We have estimated a total accretion flux from the spectroscopic metal lines of $|\dot{\rm M}| = 1.784 \times 10^{9}\,$g s-1.

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Federico Marocco

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