Stellar Autopsies from White Dwarf Pulsations

Conference presentation, 25 min. September 2018: PHysics of Oscillating STars, Banyuls-sur-mer, France

Transcript

1. http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at Chapel Hill Stellar Autopsies from White Dwarf Pulsations
4. =160 copies!
5. 170,000 K have the highest number of detected modes. The first class of pulsating s 5.5 5.0 4.5 Planetary Nebula Main sequence DOV DBV DAV 4.0 3.5 3.0 log [T eff (K)] 4 2 0 –2 –4 log (L/L ) Figure 3 H He CO ¤ White dwarfs: Peering 6 Gyr into our Sun’s future… See wonderful reviews by: Winget & Kepler 2008 Fontaine & Brassard 2008 Althaus, Córsico, Isern & García-Berro 2010
6. KIC08626021: Noemi Giammichele et al. 2018 Core Surface ß 99% of mass X(O) = 78.03% ± 4.2% X(C) = 21.96% ± 4.2% X(He) = 0.0113% ± 0.006% With enough pulsation modes we can model entire white dwarf
7. 1000 s 200 s 500 s 125 s White Dwarfs: g-modes, not all modes are observed excited BiSON; Thompson et al. 2003 5 min 4 min 6 min Solar p-modes My focus today: On observations of driving & dynamics in white dwarfs
8. 1000 s 200 s 500 s 125 s White Dwarfs: g-modes, not all modes are observed excited l=1 l=2
9. 1000 s 200 s 500 s 125 s White Dwarfs: g-modes, not all modes are observed excited l=1 l=2
10. External Constraints: Spectroscopy à Atmospheric Params. SDSS 4.2m SOAR telescope WDs Evolve (Cool) à Blue: Observed by Kepler Open: Ground-based fits via Pier-Emmanuel Tremblay Note: Most white dwarfs: 0.55-0.70 M ¤ (evolved from 1.0-3.0 M ¤ ZAMS)
11. Blue: Observed by Kepler Open: Ground-based External Constraints: Spectroscopy à Atmospheric Params.
12. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven
13. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven
14. SDSS Hermes et al. 2017c 500 s 200 s 118 s Nyquist ambiguity EPIC 211914185 Kp = 18.9 mag
15. Hermes et al. 2017c 500 s 200 s 118 s Prot : 1.13
    0.02 hr Ground-based time-series photometry breaks Nyquist ambiguity EPIC 211914185 l = 1 n = 1 l = 1 n = 2 MWD : 0.87 ± 0.03 M¤ MProg. : 4.0 ± 0.5 M¤ This is the fastest-rotating isolated white dwarf
16. 1 10 100 WD Rotation Period (hr) 0.4 0.5 0.6 0.7 0.8 0.9 WD Mass (M ) 1.0 1.5 2.0 2.5 3.0 3.5 4.0 ZAMS Progenitor Mass (M ) 1 10 100 White Dwarf Rotation Period (hr) 0 2 4 6 8 10 12 14 N K2 C8-14 Hermes+ (2017d) Kawaler (2015) 1 d 2 d 4 d We Can Now Probe WD Rotation as a Function of Mass Most white dwarfs evolve from 1-3 M¤ ZAMS stars, and rotate with periods of 0.5-2.2 days 1 d 2 d 4 d Hermes et al. 2017d
17. 150 s 1000 s
18. 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 n = 1 l = 1 n = 2 l = 1 n = 3 Mode Period (s) N SDSSJ0051+0339, g=17.6, K2 Campaign 8 n = 1 n = 2 n = 3 n = 4 Chris Clemens et al. 2018, in prep. White Dwarfs Seismologist’s Dilemma: Often Few Modes Kepler makes mode identification relatively trivial
19. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 Mode Period (s) N l = 1 n = 1 l = 1 n = 2 l = 1 n = 3 n = 1 n = 2 n = 3 n = 4 Clemens et al. 2018, in prep. If we only plot identified l=1 (m=0) modes: Kepler makes mode identification relatively trivial White Dwarfs Seismologist’s Dilemma: Often Few Modes
20. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 Mode Period (s) N n = 1 n = 2 n = 3 n = 4 l = 1 n = 1 l = 1 n = 2 l = 1 n = 3 Clemens et al. 2018, in prep. If we only plot identified l=1 (m=0) modes: Kepler makes mode identification relatively trivial White Dwarfs Seismologist’s Dilemma: Often Few Modes
21. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 DAV periods, observed Full evolutionary models computed by Romero et al. 2012 Clemens et al. 2018, in prep. White Dwarfs Seismologist’s Dilemma: Often Few Modes
22. Drawing from a random distribution of all hydrogen layer masses Full evolutionary models computed by Romero et al. 2012 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 DAV 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 Clemens et al. 2018, in prep. White Dwarfs Seismologist’s Dilemma: Often Few Modes
23. 0 1 2 3 4 5 6 7 8 50 100 150 200 250 300 350 400 450 l=1 DAV 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 Romero et al. 2012 Only drawing from the models with canonically thick (10-4 MH /M
    ) hydrogen layers Clemens et al. 2018, in prep. Most (>80% of) DAVs Have Thick H Layers
24. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven
25. Kepler Has Revealed a Dichotomy of Mode Linewidths Two modes within the same DAV show very different linewidths (Absolutely no way to have made these measurements before Kepler)
26. Kepler Has Revealed a Dichotomy of Mode Linewidths Results from fitting Lorentzians to power spectra of 27 DA white dwarfs: Clear dichotomy at ~800 s Hermes et al. 2017d
27. ’Mottled’ Modes: Outside of Mode Cavity is Base of CZ Damping rather than driving important for broadening; phase incoherence ‘Mottled’ modes: bounded by the base of the convection zone! Mike Montgomery et al. 2018, in prep.
28. Used to Be, Getting Data Required Going to the Telescope
30. *PG 1159 star = hot pre-white-dwarf (aka DOV)
31. Vauclair et al. 2002 Maidanak Observatory, Uzbekistan 2-week coordinated, global (14-site) Whole Earth Telescope run in 1994
32. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
33. Jul 27th Uzbeks introduced new rules for the visas ... spent long 8 night hours in the old stinking Russian bus, which, using longest possible route and stopping more than ten times for the repairs, after which passengers were supposed to push the bus to start the engine, brought us to Shakhrisabz. Jul 28th Old military jeep, which exhaust went more inside than via its pipes, after 5 hours brought us to Maidanak [Observatory]. ... Some windows of our living house were broken, no clean sheets ... no butter, meat, sugar. Running water system was not working anymore, not to mention hot water. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
34. Jul 29th I checked telescope; tracking and positioning were working, but telescope mirrors needed cleaning... Jul 30th Managed to repair distiller and to get 3 L of water late in the evening. Decided to wash mirrors next day. Still lots of yellow Afghanistan dust in the sky. Jul 31st Washed mirrors, cleaned telescope inner surfaces from thick dust layer. Started the full scale system test. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
35. Aug 1st All day no clouds, but wind increasing to the evening. Worked all night. Aug 3rd All day clear sky with some clouds. Quite strong wind in day time but diminished before the night. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
36. Aug 5th It was first night there on the mountain without me. I was at that time in Kitab Hospital severely injured by the Tashkent Astrophysical Institute Director son Iskander Yuldashbaev, apparently mentally ill young man of about 21. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
37. Aug 5th It was first night there on the mountain without me. I was at that time in Kitab Hospital severely injured by the Tashkent Astrophysical Institute Director son Iskander Yuldashbaev, apparently mentally ill young man of about 21. He did some cleaning ... suddenly saying no words grabbed my hair with his left hand and hit my throat with a broken knife from our kitchen. I ran in horror, but he managed to hit me twice into my back. I ran to the Russian house for the help all in the blood. It was no phone connection with outside world and two of them had to run all the way to Maidanak to soldiers, and in three hours at last I was delivered to Kitab hospital in rather weak condition. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev
38. THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev Aug 5th It was first night there on the mountain without me. I was at that time in Kitab Hospital severely injured by the Tashkent Astrophysical Institute Director son Iskander Yuldashbaev, apparently mentally ill young man of about 21. He did some cleaning ... suddenly saying no words grabbed my hair with his left hand and hit my throat with a broken knife from our kitchen. I ran in horror, but he managed to hit me twice into my back. I ran to the Russian house for the help all in the blood. It was no phone connection with outside world and two of them had to run all the way to Maidanak to soldiers, and in three hours at last I was delivered to Kitab hospital in rather weak condition. ... He is in a custody now and cannot say the reason either, says he did not like the way I looked at him. But he was smart enough to steal before that event good sum of my money ... Until helicopter arrived I explained the basics of the work with the quilt program to Alexey -- my assistant. Luckily I trained him on almost everything...
39. Aug 10th Alexey arrived from the Maidanak in the afternoon. Everything seems OK. Aug 11th Aug 12th I lived in the Russian hotel in Kitab ... working with data: writing logs, marking bad points. Tomorrow night Uzbeks promised to bring me to the Samarkand airport. My throat is swollen, still hurts and ugly. END OF CAMPAIGN HERE IN THE UZBEKISTAN ------------------------------------------------------------------------ THE MAIN LOG Observations at Maidanak observatory in Uzbekistan. Aug 1994 Observers: E. Meistas, and local assistant Alexey V. Chernyshev Aug 8th I ... practically defected from Kitab hospital, where black bugs were running on the walls at night even in the patient's beds, over the face too. Throat is badly swollen and hurts.
42. Today We Are Spoiled with Telescopes in Space
44. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven and mode density rapidly increases
45. A Visual Guide to Outbursts in Pulsating White Dwarfs Quiescent pulsations (All outburstersdominant >800 s) PG 1149+057: Hermes et al. 2015b see also Bell et al. 2015, 2016 recurrence time: chaotic; days to weeks duration: 2-20 hr excess energy: 1033-34 erg 15% flux increase: 700 K Teff increase
46. Outbursting DAVs are Among the Coolest DAVs Blue: Observed by Kepler Red: Outbursting DAV Open: Ground-based more than 50% of DAVs from 11,200-10,600 K show outbursts in ~70 days of K2 monitoring 16/71 (>20% of) DAVs with Kepler data show outbursts
47. GD 1212: The Brightest Outbursting White Dwarf Quiescent pulsations (1135.2 s, 856.9 s, …) In Outburst (864.1 s, 846.4 s, …) GD 1212: Hermes et al. 2018, in prep. >60 days between outbursts! K2 Campaign 12
48. K2 Campaign 12
49. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven and mode density rapidly increases
50. l=1 l=2 Adiabatic Model: 11,245 K, 0.632 M¤ , 10-4.12 MH /MWD Observed: 11,060(170) K, 0.64(0.03) M¤ (Romero et al. 2012) (Gianninas et al. 2011) Outbursts: Mode Coupling via Parametric Resonance à Driving exceeds damping Radiative damping ß outbursts are likely “limit cycles arising from sufficiently resonant 3-mode couplings between overstable parent modes and pairs of radiatively damped daughter modes” Luan & Goldreich 2018
51. à Driving Radiative damping ß l=1 l=2 Adiabatic Model: 11,245 K, 0.632 M¤ , 10-4.12 MH /MWD Observed: 11,060(170) K, 0.64(0.03) M¤ (Romero et al. 2012) (Gianninas et al. 2011) ωp = 897.7 µHz (l=1, m=0, n=24) Outbursts: Mode Coupling via Parametric Resonance
52. ωp = 897.7 µHz (l=1, m=0, n=24) ωd1 = 435.9 µHz (l=2, m=0, n=88) l=1 l=2 ωd2 = 461.9 µHz (l=1, m=0, n=48) Adiabatic Model: 11,245 K, 0.632 M¤ , 10-4.12 MH /MWD Observed: 11,060(170) K, 0.64(0.03) M¤ (Romero et al. 2012) (Gianninas et al. 2011) Wu & Goldreich 2001 ωd1 + ωd2 = ωp + δω Limit cycle if: δω < γd (typical 1/γd < 1 day) Outbursts: Mode Coupling via Parametric Resonance
53. 150 s 1000 s as white dwarfs cool: convection zone deepens and longer-period (higher-radial-order) pulsations driven and mode density rapidly increases