153 DA1 (38,500 K) Bohlin, Colina & Finley 1995 HZ 43 DA1 (50,000 K) Nearby (3”) dM The HST White Dwarf Standards … JWST will likely use four primary white dwarfs as absolute flux standards … dark energy studies with Type Ia supernovae pushing towards <1% flux calibration “the primary reference standards that are recommended for all ultraviolet and optical absolute calibrations from 1000 to 10,000 Å”
(just two >3 months) K2 through Campaign 10: >1100 WDs observed 43 pulsating WDs K2 through Campaign 16: >2000 WDs (if our GO proposal is !), >90 pulsating WDs (~280 known today) K1 K2, today K2, by mid-2018 K2 is providing a growing empirical test of white dwarf flux stability!
all spectroscopically confirmed WDs in Kepler/K2 are flux constant to <1% on 30-min to 10-day timescales 5/252 spectroscopic WDs >1% var. 9/424 with WD colors/proper motions Kp < 19.0 mag Cut: Pulsating WDs (SC) & known SDSS WD+dM (sdss-wdms.org) Zhichao Xue & Brad Schaefer are exploring white dwarf stability at mmag levels
a hot (>31,000 K) DB: PG 0112+104 No spectroscopic evidence for Zeeman splitting Hermes et al. 2017, arXiv: 1612.07807 (Spots Appear on Weakly Magnetic WDs, As Well) 10.17404 hr surface rotation period (peak-to-peak amplitude <0.3%)
and pulsations beware weakly magnetic WDs >25,000 K summary slide (like eating dinner for dinner) >97% of isolated WDs are constant to <1% on 30-min to 10-d timescales reflection, eclipses, spots, pulsations, outbursts surface spots visible even with <10 kG magnetic fields