Improved white dwarf cooling ages using asteroseismology and eclipsing binaries

70d4f7eb14525537a3fd6c15a33a8ac1?s=47 jjhermes
September 21, 2017

Improved white dwarf cooling ages using asteroseismology and eclipsing binaries

Conference presentation, 15 min. Sept. 2017: Ages^2: Taking Stellar Ages to the Next Power, Isola de Elba, Italy.

70d4f7eb14525537a3fd6c15a33a8ac1?s=128

jjhermes

September 21, 2017
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  1. 1.

    http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at

    Chapel Hill Improved white dwarf cooling ages using asteroseismology and eclipsing binaries
  2. 3.

    Star Trek writer James Blish put planet Vulcan in orbit

    around 40 Eri A The age of 40 Eri A is ~1.8 Gyr
  3. 4.

    Star Trek writer James Blish put planet Vulcan in orbit

    around 40 Eri A The age of 40 Eri A is ~1.8 Gyr 40 Eri, S. Smith
  4. 5.

    40 Eri, S. Smith Star Trek writer James Blish put

    planet Vulcan in orbit around 40 Eri A 40 Eri B: coeval white dwarf with total age ~1.8 Gyr I have evolved telepathy in less than 2 billion years…
  5. 6.

    Bond, Bergeron & Bédard 2017, arXiv: 1709.00478 0.573±0.018 M¤ 17,200±110

    K WD Cooling Age: ~122 Myr + Cluster-Calibrated Initial-to-Final Mass Relation (Kalirai’s talk): 1.8 M¤ Progenitor: ~1.7 Gyr MS age 40 Eri, S. Smith ~35 AU ~400 AU Thin H-layer Thick H-layer Precision mass-radius measurements can constrain envelope masses à Better cooling ages (Dynamical) (Parallax) 40 Eri B Total Age ~1.8 Gyr
  6. 7.

    WD+dM Eclipsing Binaries: <2% WD Masses, Radii High-precision study of

    16 detached WD+dM using X-shooter (double-lined velocities) + ULTRACAM (scaled radii) Steven Parsons et al. 2017, MNRAS, 470, 4473
  7. 8.

    WD+dM Eclipsing Binaries: <2% WD Masses, Radii No evidence for

    very thin H layers in 13 white dwarfs in close WD+dM binaries: All have <10-8 MH /M Parsons et al. 2017, MNRAS, 470, 4473 He-core models C/O-core models Thick H (10-4) Thin H (10-10)
  8. 9.

    Asteroseismology: Pulsations Constrain Envelope Masses Detailed study of two superficially

    similar pulsating WDs: GD 165 and Ross 548 Noemi Giammichele et al. 2015, ApJ, 815, 56 Time (s) Rel. Flux Rel. Flux Both white dwarfs have Teff ~ 12,100 K and are ~0.64 Msun but quite different pulsation properties
  9. 10.

    Asteroseismology: Pulsations Constrain Envelope Masses Thick H Layer: 10-4.23±0.15 MH

    /M He Layer: 10-1.70±0.13 MHe /M Giammichele et al. 2016, ApJS, 223, 10 Thin H Layer: 10-7.45±0.12 MH /M He Layer: 10-2.92±0.10 MHe /M
  10. 11.

    Asteroseismology: Pulsations Constrain Envelope Masses Thick H Layer: 10-4.23±0.15 MH

    /M He Layer: 10-1.70±0.13 MHe /M Giammichele et al. 2016, ApJS, 223, 10 Thin H Layer: 10-7.45±0.12 MH /M He Layer: 10-2.92±0.10 MHe /M Ross 548 (thinner envelopes) cools ~25% more slowly than GD 165 (assuming identical core composition)
  11. 12.

    Original Kepler Mission (4 years): Just 20 white dwarfs observed,

    6 pulsating WDs (just two >3 months) K2 through Campaign 13: >1200 white dwarf candidates observed 53 more pulsating WDs K2 has given us hundreds of candidate pulsating white dwarfs to observe
  12. 13.

    l = 2 l = 2 l = 1 l

    = 1 SDSSJ0106+0145, K2 Campaign 8 Hermes et al. 2017, ApJS, in press; k2wd.org K2 is giving us exceptional data for WD asteroseismology k k = Number of radial nodes l = Number of vertical nodes m = Number of horizontal + vertical nodes
  13. 14.

    Asteroseismology: Insights from the Aggregated Periods Chris Clemens, Bart Dunlap

    et al. 2017, in prep. 239 periods from 75 hot DAVs (mostly ground-based) Histogram of periods 0 5 10 15 20 25 30 50 100 150 200 250 300 350 400 450 500 0 5 10 15 20 25 30 50 100 150 200 250 300 350 400 450 Mode Amplitude (ppt) N Mode Period (s) Mode Period (s)
  14. 15.

    Asteroseismology: Insights from the Aggregated Periods If we only plot

    identified l=1 modes: 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l = 1 k = 1 l = 1 k = 2 l = 1 k = 3 Kepler makes mode identification relatively trivial Mode Period (s) N Clemens et al. 2017, in prep. SDSSJ0051+0339, g=17.6, K2 Campaign 8 k2wd.org k = 1 k = 2 k = 3 k = 4
  15. 16.

    Asteroseismology: Insights from the Aggregated Periods If we only plot

    identified l=1 modes: 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 Kepler makes mode identification relatively trivial Mode Period (s) N Clemens et al. 2017, in prep. l = 1 k = 1 l = 1 k = 2 l = 1 k = 3 k = 1 k = 2 k = 3 k = 4
  16. 17.

    Asteroseismology: Insights from the Aggregated Periods If we only plot

    identified l=1 modes: 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 Kepler makes mode identification relatively trivial Mode Period (s) N k = 1 k = 2 k = 3 k = 4 Clemens et al. 2017, in prep. l = 1 k = 1 l = 1 k = 2 l = 1 k = 3
  17. 18.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462
  18. 19.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. Drawing from a random distribution of models with a range of thick (10-4 MH /M ) to thin (10-10 MH /M ) hydrogen layer masses, using the measured spectroscopic Teff & masses for each pulsating WD Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 random MH simulation
  19. 20.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 random MH simulation l=1 canonical MH simulation Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462 Only drawing from the models with canonically thick MH
  20. 21.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 random MH simulation l=1 canonical MH simulation Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462 Only drawing from the models with canonically thick MH *The majority of WDs have canonical (thick) envelopes*
  21. 23.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. Ross 548 GD 165 l = 1, k = 2 l = 1, k = 1 Thick H Layer: ~10-4 MH /M He Layer: ~10-1.7 MHe /M “Canonical” nuclear burning sets envelope masses Thin H Layer: <10-7 MH /M ~He Layer: 10-2.9 MHe /M Very late thermal pulses? Giammichele et al. 2016, ApJS, 223, 10 size = amplitude of mode
  22. 24.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. Ross 548 GD 165 l = 1, k = 2 l = 1, k = 1 Thick H Layer: ~10-4 MH /M He Layer: ~10-1.7 MHe /M “Canonical” nuclear burning sets envelope masses Thin H Layer: <10-7 MH /M ~He Layer: 10-2.9 MHe /M Very late thermal pulses? Interpulse interaction? Giammichele et al. 2016, ApJS, 223, 10 size = amplitude of mode ~80% of DAs have canonically thick (~10-4 MH /M ) envelopes ~20% of DAs have thinner (~10-7-9 MH /M ) envelopes à WDs with 1 dex thinner He envelopes cool >10% slower! N = 14 N = 4
  23. 25.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 canonical MH simulation Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462 Only drawing from the models with canonically thick MH
  24. 26.

    Asteroseismology: Insights from the Aggregated Periods Clemens et al. 2017,

    in prep. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 hDAV periods, observed 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 canonical MH simulation Full evolutionary models computed by Alejandra Romero et al. 2012, MNRAS, 420, 1462 10-15 s offset: Suggests He-layer masses too thick in canonical models à Would lead to systematically younger WD cooling ages Only drawing from the models with canonically thick MH
  25. 27.

    Tuning the White Dwarf Clocks with Eclipses & Pulsations A

    ‘typical’ white dwarf electron degenerate C/O core (r = 8500 km) non-degenerate He layer (260 km) non-degenerate H layer (30 km) [thermal reservoir] [insulating blanket] - Seismology: ~80% of WDs have canonically thick envelopes - Those with thinner He layers can cool >10-25% more slowly - Seismic evidence that those with thick MH may have thinner MHe (are systematically older than we think) - K2 data still coming in: Expect many core C/O ratio constraints very soon!