Detection and Preliminary Characterisation of Polluted White Dwarfs from Gaia EDR3 and LAMOST

Kavli Affiliate: Sara Seager

| First 5 Authors: Mariona Badenas-Agusti, Andrew Vanderburg, Simon Blouin, Patrick Dufour, Javier ViaƱa

| Summary:

We present a catalogue of 62 polluted white dwarfs observed by the 9th
Low-Resolution Data Release of the Large Sky Area Multi-Object Fiber
Spectroscopic Telescope (LAMOST LRS DR9v1; R$approx$1,800) and the Early Data
Release 3 (EDR3) of the Gaia Mission. Among these stellar remnants, 30 are new
discoveries with previously unknown traces of calcium pollution. To generate
our catalogue, we used a database of 4,324 unique Gaia EDR3 white dwarf
candidates with LAMOST LRS DR9v1 observations, many of which have been
spectroscopically confirmed by other telescopes. For these stars, we developed
a quantitative method to detect calcium absorption in their spectra between
3,900-4,000$mathring {mathrm A}$, which we then validated through visual
inspection and multiple literature cross-checks. Our catalogue provides the
astrometric and photometric properties of the white dwarf candidates,
incorporates supplementary data (e.g. Montreal White Dwarf Database, MWDD;
PanSTARRS; the Hubble Space Telescope), and indicates the possibility of
calcium pollution in their atmospheres. For our final sample of polluted white
dwarfs, we also determine the main atmospheric properties of 23 sources with
effective temperatures $T_{rm eff}$$leq$25,000K and no existing calcium
abundances in the MWDD. Our analysis represents a first step towards measuring
the full atmospheric composition of these stars and learning about the bulk
properties of their accreted material. As we venture into the era of wide-field
spectroscopic surveys, our work highlights the importance of combining
large-scale databases for identifying and characterising new polluted white
dwarfs.

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