FAQ


Why is MY paper, which contains VERY important results, not included in the database?

We apologize to all authors who feel their work has not been considered. In the first version of the database, we included about one hundred papers picked solely from my memory (we had to start somewhere). I have surely forgot many important papers. The absence of a paper in MWDD does not in any way represent a judgement on the quality of any study. Simply let us know (or even better, create the .csv file for that paper and send it to us, see Database description) and the paper will be linked with MWDD.

See: How to include a new paper in MWDD


How were the WD candidates (CND) selected?

Our white dwarf candidate sample is based on the Gaia Data Release 2. We first selected objects within 100 pc of the Sun, allowing for the error on the parallax measurement. To clean the sample, we used the recommendations described in Lindegren et al. (2018) to remove non-Gaussian outliers in color and absolute magnitude. As noted by Lindegren et al. (2018), these criteria may filter out binary systems, in particular white dwarf + main-sequence binaries. We also limit our sample to objects with >10σ significant parallax, GBP, and GRP photometry. Finally, we perform a cut in the (GBP-GRP)–MG plane to select our white dwarf candidates. The ADQL query used to define our sample is provided below:

SELECT * FROM gaiadr2.gaia_source
WHERE (parallax + parallax_error) > 10.
AND parallax_over_error > 10.
AND visibility_periods_used > 5
AND phot_bp_rp_excess_factor < 1.3+0.06*power(phot_bp_mean_mag-phot_rp_mean_mag,2) 
AND phot_bp_rp_excess_factor > 1.0+0.015*power(phot_bp_mean_mag-phot_rp_mean_mag,2)
AND astrometric_chi2_al/(astrometric_n_good_obs_al - 5) < 1.44*greatest(1,exp(-0.4*(phot_g_mean_mag-19.5)))
AND (phot_g_mean_mag + 5.0*log10(parallax/100.0)) > (3.333*(phot_bp_mean_mag - phot_rp_mean_mag) + 8.333)

More questions to come


















The Montreal White Dwarf Database is produced and maintained by Prof. Patrick Dufour (Université de Montréal) and Dr. Simon Blouin (LANL). Please send database updates, corrections, suggestions or bug reports to patrick.dufour@umontreal.ca.