Paparazzi lightning: 68 million images of white dwarfs from space

Conference presentation, 20 min. October 2019: White Dwarfs as probes of fundamental physics and tracers of planetary, stellar & galactic evolution, IAU Symposium 357, Hilo, HI, USA.

Transcript

1. http://jjherm.es @jotajotahermes J.J. Hermes Paparazzi lightning: 68 million images of white dwarfs from space with help from Boris Gänsicke, Steve Kawaler, Sandra Greiss, Pier-Emmanuel Tremblay, Nicola Pietro Gentile Fusillo, Roberto Raddi, Keaton J. Bell, Erik Dennihy, Bart Dunlap, Chris Clemens, Mike Montgomery, Don Winget, Tom Marsh, Seth Redfield, Mukremin Kilic, Matt Burleigh, Ian Braker, Stéphane Charpinet, Noemi Giammichele, Judi Provencal, et al.
2. Accounting for 68 million WD images in Kepler & K2 All K2 selection was done without Gaia DR2 (Hundreds more candidate WDs were observed by programs led by Matt Burleigh, Steve Kawaler, Mukremin Kilic, John Lewis, and Seth Redfield but turned out to be non-WDs) JJ Hermes, Boston University | IAU 357: WD Tracers | 2 2212 unique WDs with long- cadence (30-min) exposures: 7.1 million frames 572 unique WDs with short- cadence (1-min) exposures: 61.5 million frames All numbers up to Campaign 18
3. JJ Hermes, Boston University | IAU 357: WD Tracers | 3 Hermes et al. 2020, in prep. The 2212 WDs observed by Kepler/K2 as seen by Gaia 7.5 log( g ) = 9 8.5 8.0 Grey: Only photometry Black: 72% of WDs with spectra
4. JJ Hermes, Boston University | IAU 357: WD Tracers | 4 The 2212 WDs observed by Kepler/K2 as seen by Gaia 7.5 9 8.5 8.0 Hermes et al. 2020, in prep. Red: WD+MS from SDSS
5. The 2212 WDs observed by Kepler/K2 as seen by Gaia JJ Hermes, Boston University | IAU 357: WD Tracers | 5 7.5 8.5 8.0 Hermes et al. 2020, in prep. Blue: SC Pulsations Orange: Spots 9
6. How pulsating and spotted WDs look from space 0.0 0.5 1.0 1.5 2.0 Rotational Phase °3 °2 °1 0 1 Relative Flux (%) 1 0 -1 -2 -3 EC 14012-1446 (EPIC 212395381, Campaign 6), g=15.7 mag SDSSJ0344+1705 (EPIC 210609259, Campaign 4), g=17.7 mag 2.04-day, stable signal Relative Flux (%) Rotational Phase JJ Hermes, Boston University | IAU 357: WD Tracers | 6 0.0 0.5 1.0 1.5 2.0
7. JJ Hermes, Boston University | IAU 357: WD Tracers | 7 Rotation rates fall directly from K2 data of pulsators Assume Ck,l =0.47 in all cases for modes l =1 Hermes et al. 2017 k2wd.org
8. Isolated pulsating WDs rotate between 0.5-2.2 days JJ Hermes, Boston University | IAU 357: WD Tracers | 8 1 d 2 d 4 d None of the stars are currently in binaries: representative of single-star evolution of mostly 1-3 M¤ stars Hermes et al. 2017 k2wd.org
9. Magnetic spotted WDs can reach extreme rotation rates JJ Hermes, Boston University | IAU 357: WD Tracers | 9 1 d 2 d 4 d
10. A strongly magnetic WD observed in K2 Long-cadence (30-min) exposures showed a significant peak in FT at 3 ppt = 0.3% 5 hr 2 hr 1 hr SDSS ν Nyq JJ Hermes, Boston University | IAU 357: WD Tracers | 10 SDSSJ082547.52+174818.4 g=18.9 mag DC in Nicola’s DR10 catalog K2 Campaign 5
11. A strongly magnetic WD rotating at 18 min! JJ Hermes, Boston University | IAU 357: WD Tracers | 11 0.0 0.5 1.0 1.5 2.0 Rotational Phase °6 °4 °2 0 2 4 6 Relative Flux (%) ν Nyq 2ν Nyq 3ν Nyq 18.04410 min dark spot 2 hr 30 min 20 min Folded SOAR High-speed photometry from SOAR shows this was a superNyquist signal at 18 min! K2 Campaign 5 SOAR, 5-pt smoothed
12. A confluence of failures: the fastest-rotating isolated WD JJ Hermes, Boston University | IAU 357: WD Tracers | 12 1. Kepler broke, giving us the K2 mission along the ecliptic (Only 46 WDs observed in original Kepler mission.)
13. A confluence of failures: the fastest-rotating isolated WD JJ Hermes, Boston University | IAU 357: WD Tracers | 13 2. In K2 Campaign 10, CCD Module 4 failed one week into the campaign ν Nyq 1% FAP Reding et al., in prep.
14. A confluence of failures: the fastest-rotating isolated WD JJ Hermes, Boston University | IAU 357: WD Tracers | 14 Reding et al., in prep. A 315.96 s (5.3 min) signal! 3. On 24 April 2018, the SOAR Goodman slit mask motor burned out, forcing us to do photometry instead of spectroscopy. ν Nyq 3 ν Nyq 7 ν Nyq 11 ν Nyq
15. The fastest-rotating isolated WD has modulated emission! JJ Hermes, Boston University | IAU 357: WD Tracers | 15 Spectrum changes occur along the 315.96 s (5.3 min) spin period! 5.1 MG Joins GD 356 as a DAe! SOAR Reding et al., in prep.
16. Magnetic spotted WDs: Failed SN Ia, mergers JJ Hermes, Boston University | IAU 357: WD Tracers | 16 7.5 log( g ) = 9 8.5 8.0 18-min spot
17. Magnetic spotted WDs: Failed SN Ia, mergers JJ Hermes, Boston University | IAU 357: WD Tracers | 17 7.5 log( g ) = 9 8.5 8.0 18-min spot 5-min spot
18. Tons of science from 68 million images of WDs from space JJ Hermes, Boston University | IAU 357: WD Tracers e.g. Anomalously fast-rotating WDs are often strongly magnetic and likely connect to failed SN Ia The stars have set on K2, which observed >2000 WDs TESS picks up the torch: we are monitoring >3500 WDs with GRP < 16.5 mag