http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at Chapel Hill Comparing the rotation of hot subdwarfs with binary low-mass white dwarfs
http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at Chapel Hill Comparing the rotation of hot subdwarfs with binary low-mass white dwarfs and white dwarfs and clump giants
http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at Chapel Hill Comparing the rotation of hot subdwarfs with binary low-mass white dwarfs and white dwarfs and clump giants
http://jjherm.es J.J. Hermes Hubble Fellow University of North Carolina at Chapel Hill Comparing the rotation of hot subdwarfs with binary low-mass white dwarfs and white dwarfs and clump giants
From the outside looking in: “How fast do hot subdwarfs rotate?” Comparing the rotation of hot subdwarfs with binary low-mass white dwarfs and white dwarfs and clump giants
What Stephan says: sdB rotation from v sin i Nearly 100 sdBs with Porb > 1.2 d or no RV variability: rotation velocities between 5-10 km/s “< 10 km/s” Geier et al. 2010 Geier & Heber 2012 For 0.20 R¤ sdBs: Expect typical rotation periods of order 0.5-3.0 days (Tides clearly affect < 4 hrPorb )
What Stéphane says: sdB rotation from seismology NY Vir (aka PG 1336-018): Charpinet et al. 2008 Much faster rotation is observed for NY Vir, a synchronized sdB in a 2.42-hr binary with a 0.11-0.12 M¤ dM companion (Vuckovic+ 2007) Solid body rotation within ~50-100% of star by radius (g-modes resonate there)
What Kepler says: sdB rotation from seismology Baran et al. 2008 Balloon 090100001 Telting et al. 2012 KIC 11558725 Baran & Winans 2012 KIC 2438324 Baran & Winans 2012 KIC 10139564 Pablo et al. 2012 KIC 2991403 Pablo et al. 2012 KIC 11179657 Østensen et al. 2012 KIC 1718290 Østensen et al. 2014 KIC 10553698 Telting et al. 2014 KIC 7668647 Reed et al. 2014 KIC 10670103 Foster et al. 2015 KIC 3527751 Baran et al. 2016 KIC 7664467 Ketzer et al. 2017 EPIC 203948264 Kern et al. 2017 KIC 2697388 g-mode splittings from Kepler suggest sdB rotation periods ranging from ~7-100 days All published Kepler sdBs are subsynchronouslyrotating For those in binaries, Porb span 0.4-14 days
Original Kepler Mission (4 years): Just 20 white dwarfs observed, 6 pulsating WDs (just two >3 months) K2 through Campaign 10: >1000 white dwarf candidates observed 35 more pulsating WDs K2 has given us hundreds of candidate pulsating white dwarfs to observe
m = +1 m = -1 m = 0 125 s 316.8 s 345.3 s n = Number of radial nodes l = Number of vertical nodes m = Number of horizontal + vertical nodes n l = 1 n = 5 l = 1 n = 6 Prot = 0.9 ± 0.1 day Fourier transform, 75 days data white dwarf from K2 Campaign 1 200 s 500 s 1000 s We Can Decompose Pulsations into Spherical Harmonics
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 N Kepler & K2 Kawaler (2015) 1 d 2 d 4 d Hermes et al. 2017, in prep. All <0.75 M ¤ Pulsating WDs Rotate from 0.2-5.5 days We have obtained WHT/SOAR spectra of all pulsating white dwarfs in Kepler/K2: All will be publicly available at k2wd.org Hermes et al. 2017, ApJL, 841, L2; arXiv: 1704.08690
1 10 100 White Dwarf Rotation Period (hr) 0 2 4 6 8 10 N Kepler & K2 Kawaler (2015) • No isolated 0.6 M¤ WD rotates this fast • No accretion history in J1136+0409 • Common envelope evolution appears to have affected this WD’s rotation Hermes et al. 2015, MNRAS, 451, 1701 l = 1 modes m = +1 m = 0 m = -1 WD Rotation Affected by Common Envelope Evolution J1136+0409 Prot : 2.50.5 hr
ELM White Dwarfs: Products of Binary Interaction ELM White Dwarfs (<0.3 M¤ ) interacted with a binary companion before helium ignition Not good comparison with sdBs, as ELM rotation is regulated by hydrogen shell flashes: Istrate et al. 2016, A&A, 595, 35
Rotation Can Help Explain Why Many ELM WDs Show Metals Istrate et al. 2016 Istrate models predict all ELM WDs rotate supersynchronously (Prot faster than 1 day for 0.2 M¤ WD) Istrate et al. 2017, EuroWD16
sdBs Appear to Rotate with Periods from Weeks to Months Geier & Heber 2012 Typical rotation periods >1 day from v sin i g-mode splittings from Kepler suggest sdB rotation periods ranging from ~7-100 days "All stars in our sample are slow rotators (vrot sini < 10 km/s)." ?
Core He-Burning Red Giants as sdB Analogues “sdBs are core He-burning red giants without envelopes” Not an insane idea: Both sdBs and clump giants have g-mode period spacings of roughly 200-300 s g-modes p-modes
Secondary clump red giants rotate mostly rigidly Isolated core He-burning giants (2-3 M¤ ) rotate relatively rigidly (from detected p- and g-modes, core slightly faster than envelope), and appear to have lost most angular momentum Deheuvels et al. 2015 10 100 Secondary Clump Rotation Period (d) 0 1 2 3 4 5 6 7 8 N Deheuvels et al. 2015 Tayar et al., in prep. Jamie Tayar et al. 2017, in prep. Their core rotation rates range from ~30-180 days towards core towards surface
1 10 100 White Dwarf Rotation Period (hr) 0 2 4 6 8 10 N Kepler & K2 Kawaler (2015) sdB cavity ~0.03-0.15 R¤ WD cavity ~0.005-0.013 R¤ 10 100 Secondary Clump Rotation Period (d) 0 1 2 3 4 5 6 7 8 N Deheuvels et al. 2015 Tayar et al., in prep. Clump RGB cavity ~0.02-0.10 R¤ 1. What is the true rotation distribution of sdBs? 2. If many sdBs are mergers, why so slow? 3. What do these distributions say about internal angular transport during the AGB? Prot : 30-180 d Prot : 7-100 d Prot : 0.2-5 d
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