Age Calibration from Coeval White Dwarfs in K2 and TESS

Conference presentation, 20 min. January 2018: Dwarf Stars and Clusters with K2, Boston, MA, USA.

Transcript

1. http://jjherm.es
   J.J. Hermes
   Hubble Fellow, UNC Chapel Hill
   Age Calibration from Coeval
   White Dwarfs in K2 and TESS
   

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2. Star Trek writer James Blish
   put planet Vulcan in orbit
   around 40 Eri A
   

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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
   

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4. 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… ~35 au
   ~400 au
   Bond, Bergeron & Bédard 2017
   

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5. WD Teff
   /Mass à WD Cooling Age
   WD Initial-Final Mass Relation à Main-Sequence Mass/Age
   Total System Age(~30%)
   How Do We Get Coeval Ages from White Dwarfs?
   +
   =
   - Cooling ages come from WD
   evolution models
   - Calibrated by WDs in clusters with
   known turnoff ages
   WD Teff
   /log(g)
   

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6. see also Cummings et al. 2016
   How do we build an Mi
   /Mf
   relation?
   E.g.: 0.77(0.03) M¤
   WD in NGC 2527(630 Myr)
   185 Myr WD cooling age
   tprog
   = 441 Myr -> Mprog
   = 3.1 M¤
   Raddi et al. 2016
   

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7. Bond, Bergeron & Bédard 2017
   0.573±0.018 M¤
   17,200±110 K
   WD Cooling Age: ~122 Myr
   +
   Cluster-Calibrated Initial-to-Final
   Mass Relation (Cummings et al. 2016):
   1.8 M¤
   Progenitor:
   ~1.7 Gyr MS age
   40 Eri, S. Smith
   ~35 AU
   ~400 AU
   40 Eri B
   Total Age ~1.8 Gyr
   

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8. Age Calibration from Coeval
   White Dwarfs in K2 and TESS
   

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9. Rebassa-Mansergas et al.
   sdss-wdms.org
   K2 Campaign 5
   

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10. WD
    15,070(2000) K
    logg = 8.69(0.326)
    1.04(0.173) M¤
    ~0.8 Gyr total age
    M3
    0.38(0.07) M¤
    Prot
    = 4.59 d
    

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11. A handful of composite WD+dM in K2 with
    likely dM rotation periods
    - All M1−M3
    - No radial-velocity variations in SDSS subspectra
    - Spatially unresolved (all >200 pc away)
    Jennifer van Saders
    0.3 < M/M¤
    < 0.4
    −0.4 < [Z/H] < +0.4
    Fast and slow initial
    rotation rates
    

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12. Age Calibration from Coeval
    White Dwarfs in K2 and TESS
    

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13. Talbot & Gänsicke 2018, in prep.
    G0
    PMRA
    = -22.0(2.3) mas/yr
    PMDec
    = -16.0(2.4) mas/yr
    WD
    PMRA
    = -22.2(4.7) mas/yr
    PMDec
    = -24.7(4.7) mas/yr
    Distance: ~260 pc
    Projected Sep: >28000 au
    16,280(180) K
    0.61(0.02) M¤
    2.1 M¤
    progenitor
    ~1.1 Gyr total age
    

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14. 5.0 7.5 10.0 12.5 15.0
    Primary T (mag)
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
    N
    12 14 16 18 20
    WD secondary V (mag)
    0
    2
    4
    6
    8
    10
    1 10 100 1000
    Separation (arcsec)
    0
    2
    4
    6
    8
    10
    12
    N
    1.0 10.0
    Total Age (Gyr)
    0
    2
    4
    6
    8
    10
    N
    JJH, Jennifer van Saders, Boris Gänsicke, Jeff Andrews,
    Alberto Rebassa-Mansergas, Steve Kawaler, Pier-
    Emmanuel Tremblay, Julio Chanamé, Marcel Agüeros,
    Jay Farihi, James Davenport, Chris Clemens
    TESS Coeval Degenerates Survey, Cycle 1
    A-1
    F-7
    G-12
    K-12
    M-26
    

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15. Oh et al. 2017
    Andrews, Chanamé & Agüeros 2017
    Gaia will
    revolutionize
    finding common
    proper-motion
    binaries
    

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16. WD Teff
    /Mass à WD Cooling Age
    WD Initial-Final Mass Relation à Main-Sequence Mass/Age
    Total System Age
    How Do We Improve Coeval Ages from White Dwarfs?
    +
    =
    - Core C/O Ratio (where heat stored)
    - Envelope Masses (opacities, how fast heat escapes)
    - Improved MS Ages
    - More WDs in Clusters for IFMR
    - More Wide WD+WD Binaries
    WD Teff
    /log(g)
    

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17. WD Teff
    /Mass à WD Cooling Age
    WD Initial-Final Mass Relation à Main-Sequence Mass/Age
    Total System Age (~10%)
    How Do We Improve Coeval Ages from White Dwarfs?
    - Core C/O Ratio (where heat stored)
    - Envelope Masses (opacities, how fast heat escapes)
    - Improved MS Ages
    - More WDs in Clusters for IFMR
    - More Wide WD+WD Binaries
    WD Teff
    /log(g)
    White Dwarf Asteroseismology
    with K2/TESS
    Gaia
    

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18. Clusters are a party
    

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19. Coeval Degerates:
    Clusters of Two
    Calibrate gyrochronology,
    age-activity, & age-flaring
    continuously out to
    8-10 Gyr in the solar
    neighborhood
    Gaia will uncover orders
    more wide WD+MS
    binaries
    

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20. 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]
    

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