Astrometric and photometric verification of faint blue white dwarfs in the Gaia catalogue of nearby stars

Abstract

The Gaia catalogue of nearby stars (GCNS) divided all objects with parallaxes $>$10mas into GCNS-selected and GCNS-rejected 100pc samples. Below the white dwarf (WD) sequence in the complete GCNS color-magnitude diagram (CMD), at $Gabs>14.7+4.7(G-RP)$, there appear 60 GCNS-selected faint blue white dwarfs (FBWDs). However this CMD region is also populated by 411 GCNS-rejected objects, mainly from crowded regions towards the Galactic centre and the Magellanic Clouds. The WD catalog of Gentile Fusillo et al. (2021) lists only 47 GCNS-selected but also 8 GCNS-rejected objects. I confirm 59 of the GCNS-selected but none of the GCNS-rejected objects as FBWDs from visual inspection and a proper motion check using additional optical sky surveys. Hence FBWDs form an additional branch in the CMD. Compared to the full GCNS-selected 100pc sample, FBWDs have relatively high proper motions and tangential velocities. They represent interesting targets for studies of ultracool or infrared-faint, and possibly also ultramassive WDs.

5 pages, 1 figure, the file gedr3_sel_59_FBWDs.fits (not included in the RNAAS paper) contains a table of 59 confirmed FBWDs with their selected Gaia EDR3 parameters

References in corpus (6)

• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• The 100 pc White Dwarf Sample in the SDSS Footprint
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• Quasar and galaxy classification in Gaia Data Release 2
• The Most Massive White Dwarfs in the Solar Neighborhood
• The extended Gaia-PS1-SDSS (GPS1+) proper motion catalog

Cited by in corpus (4)

• Carbon-oxygen ultra-massive white dwarfs in general relativity
• White Dwarf Stars in the Big Data Era
• Search of nearby resolved neutron stars among optical sources
• Effects of light-mass fermionic dark matter on the equilibrium and stability of white dwarfs