Planetary Systems around White Dwarfs Boris Gänsicke

A large fraction of solar-like stars has planets (e.g. Cassan et al. 2012, Nature 481, 167; Fressin et al. 2013, ApJ 766, 81)

A large fraction of solar-like stars has planets (e.g. Cassan et al. 2012, Nature 481, 167; Fressin et al. 2013, ApJ 766, 81) What is the future of these systems? What is the future of the solar system ?

(almost) all planet host stars will become white dwarfs: Earth-sized, ~solar-mass e - degenerate objects

Today

5 billion years from now

The life cycle of the Sun 8 billion years from now e.g. Burleigh et al. 2002, MNRAS 331, L41

The future of the known exoplanets engulfed survived Dimitri Veras

The future of the known exoplanets Dimitri Veras engulfed survived selection effects see Sackman et al. 1993, ApJ 418, 457, Duncan & Lissauer, 1998, Icar 134, 303; Burleigh et al. 2002, MNRAS 331, L41; Villaver & Livio 2009, ApJ, 705, L81; Mustill et al. 2014, MNRAS, 437, 1404

R wd ≈ 0.01R๏ ≈ R  M wd ≈ 0.65 M๏ g=9.8ms -2 g~10 6 ms -2 Expect many white dwarf planetary systems

White dwarfs are chemically stratified H or He atmosphere ~ Mwd C/O core ~0.99 Mwd Althaus et al. 2010, A&A Rev 18, 471 Expect a pure hydrogen or helium atmosphere

The exception to the rule: Van Maanen’s star (1917) Van Maanen 1917, PASP 29, , Cont. Mt. Wilson Obs. 182 vMa2 was the 3 rd white dwarf to be discovered, at a distance of 4.4pc Ca Mg Fe External pollution, but where do the metals come from?

Zuckerman et al. 1987, Nature 330, 138; Graham et al. 1990, ApJ 357, 216; Kilic et al. 2005, ApJ 632, L115; Becklin et al. 2005, ApJ 632, L119; Reach et al. 2005, ApJ 635, L161; Jura et al. 2007, AJ 133, 1927; Kilic et al. 2007, ApJ 660, 641; von Hippel et al. 2007, ApJ 662, 544; Jura et al. 2007, ApJ 663, 1285; Farihi et al. 2008, ApJ 674,431; Jura et al. 2009, AJ 137, 3191; Reach et al. 2009, ApJ 693, 697; Farihi et al. 2009, ApJ 694, 805; Brinkworth et al. 2009, ApJ 696, 1402; Farihi et al. 2010, ApJ 714, 1386; Dufour et al. 2010, ApJ 719, 803; Vennes et al. 2010, MNRAS 404, L40; Farihi et al. 2011, ApJ 728, L8; Debes et al. 2011, ApJ 729, 4; Farihi et al. 2012, MNRAS 421, 1635; Barber et al. 2012, ApJ 760, 26 Zuckerman et al. 1987, Nature 330, 138; Graham et al. 1990, ApJ 357, 216; Kilic et al. 2005, ApJ 632, L115; Becklin et al. 2005, ApJ 632, L119; Reach et al. 2005, ApJ 635, L161; Jura et al. 2007, AJ 133, 1927; Kilic et al. 2007, ApJ 660, 641; von Hippel et al. 2007, ApJ 662, 544; Jura et al. 2007, ApJ 663, 1285; Farihi et al. 2008, ApJ 674,431; Jura et al. 2009, AJ 137, 3191; Reach et al. 2009, ApJ 693, 697; Farihi et al. 2009, ApJ 694, 805; Brinkworth et al. 2009, ApJ 696, 1402; Farihi et al. 2010, ApJ 714, 1386; Dufour et al. 2010, ApJ 719, 803; Vennes et al. 2010, MNRAS 404, L40; Farihi et al. 2011, ApJ 728, L8; Debes et al. 2011, ApJ 729, 4; Farihi et al. 2012, MNRAS 421, 1635; Barber et al. 2012, ApJ 760, 26 Dust around ~40 white dwarfs ~1-3% of all white dwarfs have IR excess due to dust, e.g.: Farihi et al. 2009, ApJ 694, 805 Girven et al. 2011, MNRAS 417, 1210 Steele et al.2011, MNRAS 416, 2768 Debes et al. 2011, ApJS 197, 38

The “standard model”: Tidal disruption of asteroids Graham et al. 1990, ApJ 357, 216 Debes & Sigurdsson 2002, ApJ 572, 556 Jura 2003, ApJ 584, L91 Bonsor et al. 2010, MNRAS 409, 1631 Bonsor et al. 2010, MNRAS 414, 930

Photospheric metal pollution by planetary debris Ca Mg Fe Jura & Young 2014, ARE&PS 42, 45

Evolved planetary system demographics: ages Ca H/K vMa2 At T<13000K Ca H/K is the strongest tracer of planetary debris Koester, Gänsicke, Farihi 2014 A&A 566, A34

Evolved planetary system demographics: ages Ca H/K vMa2 Koester, Gänsicke, Farihi 2014 A&A 566, A34 Temperature  Ca H/K  Losing sensitivity at younger WDs

T≥15000K: Si II 1260Å  UV spectroscopy Koester, Gänsicke, Farihi 2014 A&A 566, A34 Si II Evolved planetary system demographics: ages COS

Probing the frequency of evolved planetary systems Cycle 18 & 19 snapshot program: An unbiased HST/COS survey of 85 hydrogen-atmosphere white dwarfs  short diffusion time scale (days)  if polluted, these stars accrete now Koester, Gänsicke, Farihi 2014 A&A 566, A34

The fraction of WDs accreting planetary debris: 25-50% comparable to the frequency of planets around solar-like stars Evolved planetary system demographics: ages Koester, Gänsicke, Farihi 2014 A&A 566, A34 Zuckerman et al Barstow et al. 2014

The fraction of WDs accreting planetary debris: 25-50% comparable to the frequency of planets around solar-like stars Evolved planetary system demographics: ages Koester, Gänsicke, Farihi 2014 A&A 566, A34 Cycle 22 Zuckerman et al Barstow et al. 2014

The fraction of WDs accreting planetary debris: 25-50% comparable to the frequency of planets around solar-like stars Evolved planetary system demographics: ages Koester, Gänsicke, Farihi 2014 A&A 566, A34 Cycle 22 Zuckerman et al Barstow et al. 2014

Meteor crater, Arizona Measuring bulk compositions in the solar system

Measuring bulk composition in exo-planetary systems Cycle 18 & 19 snapshot program: An unbiased HST/COS survey of 85 hydrogen-atmosphere white dwarfs  short diffusion time scale:  if polluted, these stars accrete now  unambiguous abundances of the debris & updated diffusion calculations new radiative levitation calculations updated atomic physics update model atmospheres

Detailed abundance studies (Gänsicke et al. 2012, MNRAS 424, 333) O, Mg, Si, and Fe are the major constituents of the debris (and also make up ~93% of the Earth), variations similar to solar system

Detailed abundance studies (Gänsicke et al. 2012, MNRAS 424, 333) O, Mg, Si, and Fe are the major constituents of the debris (and also make up ~93% of the Earth), variations similar to solar system Carbon-depleted, similar to bulk Earth  “rocky” carbon depleted

Detailed abundance studies (Gänsicke et al. 2012, MNRAS 424, 333) O, Mg, Si, and Fe are the major constituents of the debris (and also make up ~93% of the Earth), variations similar to solar system Carbon-depleted, similar to bulk Earth  “rocky” Refractory litophiles Ca/Al very similar to solar system bodies carbon depleted same Al/Ca as in SS

Detailed abundance studies (Gänsicke et al. 2012, MNRAS 424, 333) O, Mg, Si, and Fe are the major constituents of the debris (and also make up ~93% of the Earth), variations similar to solar system Carbon-depleted, similar to bulk Earth  “rocky” Refractory litophiles Ca/Al very similar to solar system bodies Strong evidence for differentiation (Fe, S, Cr overabundance) carbon depleted same Al/Ca as in SS iron-rich

Mesosiderite-like exo-asteroids Mesosiderite “Vaca Muerta” origin from a ~ km differentiated asteroid (Scott et al. 2001, M&PS 36, 869)

So, we can measure the bulk abundances of rocky material in extrasolar planetary systems

What about water?

A water-rich parent body accreting onto GD61 Farihi, Gänsicke & Koester (2013, Science, 342, 218) mass of parent body: ~1x10 21 g - 1x10 23 g H 2 O mass fraction: 26% “Rocks” = MgO, Al 2 O 3, SiO 2, CaO, TiO 2, Cr 2 O 3, MnO, FeO, Fe 2 O 3,...  nominal O-excess of ≥20-40% COS

... similar to Ceres...

What about …

carbon-dominated chemistry Wilson et al. in prep

The most detailed insight into exo-planet chemistry Jura & Young 2014 (AREPS 42, 45)

Xu et al Cycle 17-22: 57 GO SNAP orbits (~1/3 executed) 94% The most detailed insight into exo-planet chemistry

JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST Where do we go from here?

Gaia ● Astrometric detection of white dwarf planets within a few 10pc  HST survey of nearby white dwarfs for metal pollution ● Identification of ~ white dwarf JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST

JWST JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST ● Detailed mineralogy for dozens of debris discs  Combined in-situ analysis of the debris plus detailed bulk-chemistry from HST

JWST JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST ● Detailed mineralogy for dozens of debris discs  Combined in-situ analysis of the debris plus detailed bulk-chemistry from HST Jura & Young 2014, ARE&PS 42, 45 Spitzer/IRS HST/COS Reach et al Xu et al. 2014

EUCLID/WFIRST ● Detection of 100s, maybe 1000s of dusty debris discs  Follow-up with JWST (mineralogy) JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST

ATLAST ● Ground-based spectroscopic surveys: 1000s of metal-polluted white dwarfs  Follow-up with ATLAST, detailed understanding of the bulk chemistry of the building blocks of exo-planetary systems at a similar level to the solar system  Feedback into the theory of planet formation JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST

ATLAST ● Ground-based spectroscopic surveys: 1000s of metal-polluted white dwarfs  Follow-up with ATLAST, detailed understanding of the bulk chemistry of the building blocks of exo-planetary systems at a similar level to the solar system  Feedback into the theory of planet formation JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST

ATLAST ● Ground-based spectroscopic surveys: 1000s of metal-polluted white dwarfs  Follow-up with ATLAST, detailed understanding of the bulk chemistry of the building blocks of exo-planetary systems at a similar level to the solar system  Feedback into the theory of planet formation JWST Gaia HST ATLAST WEAVE/DESI/4MOST EUCLID/WFIRST

Late dynamical instabilities Veras & Gänsicke 2015 (MNRAS 447, 1049)

The formation of these debris discs is complex Veras et al (MNRAS 445, 2244) & 2015 submitted

From Rosswog et al. 2009, ApJ 695, 404 (but this is a totally different story)

Line variability – tracing tidal debris streams?

Gänsicke et al. 2006, Science 314, 1908, Manser et al. in prep Indirect imaging of debris discs around white dwarfs

Pluto ~1.3x10 25 g Charon ~1.5x10 24 g Moon ~7.3x10 25 g Big asteroids...! Eris ~1.7x10 25 g Ceres ~9.4x10 23 g Earth ~7.0x10 27 g Minimum mass of the accreted debris: SDSS ~ 4.8x10 23 g (Koester et al. 2011, A&A 530, A114) SDS ~ 6.3x10 23 g (Dufour et al. 2012, ApJ 749, 6) HE 0446−2531 ~ 8.0x10 24 g (Girven et al. 2012, ApJ 749, 154)

WD masses Evolved planetary system demographics: masses

WD masses  IMF relation (Bildsten talk) Evolved planetary system demographics: masses

WD masses  IMF relation  progenitor masses (Bildsten talk) A-stars Evolved planetary system demographics: masses

WD masses  IMF relation  progenitor masses > 50% of WDs descending from 2-3M๏ MS stars accrete planetary debris  The formation of planetary systems around A-type stars is efficient A-stars

Conclusions