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Galah and Asteroseismology Galah and asteroseismology Dennis Stello The asteroseismic revolution pre-2007 ~10 dwarfs & subgiants ~8 giants Ground-based radial velocity. WIRE star tracker. MOST spacecraft. figure by Daniel Huber Kepler 2010-13 ~ 600 dwarfs & subgiants ~ 20000 giants figure by Daniel Huber Early results from Kepler Pinsonneault et al. 2016 Log(g) Teff Photometry APOGEE Red Giants/original Kepler field Early results from Kepler Snapping into focus Pinsonneault et al. 2016 Log(g) Teff Teff Photometry Spectroscopy APOGEE Red Giants/original Kepler field Early results from Kepler Snapping into focus Pinsonneault et al. 2016 Log(g) Teff Teff Teff Photometry Spectroscopy Spectroscopy + asteroseismology APOGEE Red Giants/original Kepler field A short introduction to cool-star asteroseismology Asteroseismology of cool stars Excitation of solar-like oscillations Excitation of solar-like oscillations Miso soup Excitation of solar-like oscillations Standing sound waves (p modes) Observing oscillation modes Velocity Brightness Light is red/blue shifted Frequency (DopplerSun: effect) 20cm/sBrightness variation4ppm Red giant: 1-100m/s 30-300ppm Sound speed Interior properties How we do it! Virgo data of the Sun FT Overtone determined by number of nodes (shells) radially. 1 0 1 0 1 2 2 0 2 Zoom Spherical degree determined by number of `surface’ nodal lines. How we do it! Virgo data of the Sun FT -4 -6 Overtone determined δf/f ~ 10 -10 by number of nodes (shells) radially. 1 0 1 0 1 2 2 0 2 Zoom Spherical degree determined by number of `surface’ nodal lines. What can we measure? FT Age of star 1 0 1 0 1 2 2 0 2 Zoom Radial modes (l = 0) H He H Ages of main sequence stars sequence main of Ages But there is more 0.5 νmax ~ g/(Teff) FT ∆ν ~ ρ1/2 Age of star 1 0 1 0 1 2 2 0 2 Zoom Age precisions • Individual mode fitting (or frequency ratios): • Main sequence: ~3% (best, Metcalfe 2015), 5-15% (typical, Metcalfe 2014, Silva Aguirre 2015). • Subgiants: ~1% (best, Metcalfe 2010), ~3% (typical, Deheuvels & Michel 2011). • Red giants: < 15%(?) (very time consuming) • ∆ν+νmax (at least one scaling relation): • Main sequence: ~15% – 25% (Chaplin 2014). • Subgiants: ~15% – 25% (Chaplin 2014). • Red giants: ~15 – 30% (Casagrande 2014). Ages of red giants Spectroscopic-only constraints Seismic-included constraints Silva Aguirre & Serenelli 2016 Back to the revolution…what have we learned so far! Evolution of frequency spectra He-core burn (red clump) RGB Bump Bottom RGB MS Paxton et al. (2013) ν 1. max 2.5 ∆ν ∆ν 0 1 1 0 20 1 1 2 1 1 20 20 0 2 2 Evolution of frequency spectra He-core burn (red clump) RGB Bump Bottom RGB MS Paxton et al. (2013) ν 1. max 2.5 ∆ν ∆ν 0 1 1 0 20 1 1 2 1 1 20 20 0 2 2 Problem!!! Red Clump (He-core burning) RGB ? (non He-core burning) figure by Daniel Huber RGB/RC stars: seismically different RGB (H-shell burning) RC (He-core burning) Red Clump (He-core burning) Core size Core RGB (non He-core burning) Envelope density Ages of red giants Silva Aguirre & Serenelli 2016 Other breakthroughs!!! Magnetic green house effect Stellar inclinations: Do cluster stars’ Fuller et al. 2015 spin align? (Science) Corsaro et al. 2017 (NatureCom) Radial differential rotation and angular momentum transport A prevalence of convective core dynamos Beck et al. 2012 (Nature) Stello et al. 2016 Mosser et al. 2012 (A&A) (Nature) Ensemble seismology: Probing the structure and evolution of the Milky Way Our Galaxy Stellar halo Bulge Stellar disk(s) Hippoarcos + Copenhagen-Geneva Survey Asteroseismic probes of the Galaxy Top-down view Probes of the Galaxy Kepler Kepler Edge-on view CoRoT CoRoT Mathur et al. 2016 Credit: Miglio Ensemble seismology: M, R, L Power location: M / M ν ≅ * × max 2 3.1mHz (R / R* ) Teff /Teff ,* Frequency spacing: (M / M )1/ 2 ∆ν ≅ * × µ 3/ 2 135 Hz (R / R* ) ∆ν 1 0 1 2 2 0 2 1 0 Ensemble seismology: M, R, L Power location: M / M * ν max ≅ ×3.1mHz (R / R )2 T /T * eff eff ,* distance Frequency spacing: (M / M )1/ 2 ∆ν ≅ * ×135µHz 3/ 2 R, Teff L (R / R* ) ∆ν 1 0 1 2 2 0 2 1 0 Ensemble seismology: M, R, L Power location: M / M * ν max ≅ ×3.1mHz (R / R )2 T /T * eff eff ,* distance Age Frequency spacing: (M / M )1/ 2 ∆ν ≅ * ×135µHz 3/ 2 Mass R, Teff L (R / R* ) ∆ν Miglio 2012 1 0 1 2 2 0 2 1 0 Ensemble seismology: M, R, L Power location: Whole-sale seismology! M / M * ν max ≅ ×3.1mHz (R / R )2 T /T * eff eff ,* distance Age Frequency spacing: (M / M )1/ 2 ∆ν ≅ * ×135µHz 3/ 2 Mass R, Teff L (R / R* ) ∆ν Miglio 2012 1 0 1 2 2 0 2 1 0 Ensemble seismology: M, R, L Power location: Whole-sale seismology! M / M * ν max ≅ ×3.1mHz (R / R )2 T /T * eff eff ,* distance Typical precisions: Age Frequency spacing:∆ν 0.1-1% ν (M / M )1/ 2 max 0.5-2% ∆ν ≅ * ×135µHz 3/ 2 -----------------------------Mass R, Teff L (R / R* ) ∆ν Log(g) 0.01-0.03Miglio dex2012 1 Radius 0 2-3%1 2 2 0 Mass 6-10% 2 1 0 Age 15-30% Distance 3-5% Early results from Kepler and CoRoT Population synthesis of red giant stars Radius Mass Age Differential comparison between two fields/populations Thin disk Thick disk Miglio, Chiappini, Morel et al. 2013 Early results from Kepler and CoRoT (model) Mass (MSun) Radius (RSun) Sharma, Stello, Bland-Hawthorn et al. (2016) Direct comparison with Galaxy model Early results from Kepler and CoRoT (model) Not a good match in mass! Mass (MSun) Radius (RSun) Sharma, Stello, Bland-Hawthorn et al. (2016) Is this mismatchDirect comparison because with Galaxy model of unknown selection effects OR because our galactic model is inadequate? Extremely important to understand. Otherwise we can not expect to make useful comparisons! K2: The concept K2: A new opportunity for Galactic Archaeology Each campaign field: 10-30K stars observed for ~80 days 2014 Fields Campaign 1 2015 Fields Campaign 17 Campaign 14 2016 Fields Campaign 10 2017 Fields Campaign 6 Campaign 16 2018 Fields Campaign 15 Campaign 5 Campaign 2 Campaign 18 Campaign 11 Campaign 0 Campaign 13 Campaign 9 Campaign 7 Campaign 4 Campaign 19 Campaign 3 Campaign 8 Campaign 12 The K2 Galactic Archaeology Program (GAP) The thrust: Use seismology of red giants (K2) combined with Teff and [Fe/H] (ground-based) to probe the structure of the Milky Way PI: Dennis Stello, CoIs: Derek Buzasi, Ken Freeman, Savita Mathur, Andrea Miglio, Sanjib Sharma, Marc Pinsonneault, Collaborators: Friedrich Anders, Borja Anguiano, Martin Asplund, Sarbani Basu, Paul Beck, Othman Benomar, Maria Bergemann, Joss Bland-Hawthorn, Tiago Campante, Luca Casagrande, Peter De Cat, Márcio Catelan, Bill Chaplin, Cristina Chiappini, Enrico Corsaro, Orlagh Creevey, Eric Depagne, Patrick Eggenberger, Yvonne Elsworth, Jianning Fu, Rafael A. Garcia, Leo Girardi, Jennifer Johnson, Ulrike Heiter, Saskia Hekker, Paola Marigo, Eric Michel, Annie Robin, Maurizio Salaris, Victor Silva Aguirre, Marica Valentini (+ many more) K2 GAP targets so far Campaign Ntargets 0 452 1 8629 2 5138 Data download of seismic results: 3 3904 K2 GAP site: www.physics.usyd.edu.au/k2gap/ 4 6357 MAST: https://archive.stsci.edu/prepds/k2gap/ 5 9828 6 8312 7 4363 8 6185 9 ? 10 8947 11 4544 50% 50% oftotal K2 capacity 12 14014 - 13 5974 ~30 14 7135 15 7625 16 10672 End of mission (C0-C19): ~30-40k giants with seismic results K2 GAP targets so far Campaign Ntargets 0 452 Ground-based spectroscopy/photometry 1 8629 (Teff, [Fe/H], Abundances) 2 5138 3 3904 4 6357 5 9828 6 8312 7 4363 LAMOST 8 6185 (no logo?) 9 ? 10 8947 11 4544 50% 50% oftotal K2 capacity 12 14014 - K2-HERMES 13 5974 ~30 14 7135 15 7625 16 10672 End of mission (C0-C19): ~30-40k giants with seismic results K2-HERMES HERMES: A multi-object high-resolution spectrograph on the 4-m AAT (Australia). R=28,000, 350 stars per exposure (2 degree field). K2-HERMES: Aims to obtain spectra of all stars selected by the `K2 GAP’ in the range 9 < V < 15 (within 1 degree of the centres of the K2 CCD modules). Sparse field Dense field K2 GAP targets (black dots) K2-HERMES Status Bright Jun’17 K2 CCD module CCD K2 Faint K2 CCD module CCD K2 Dense fields K2-HERMES Status Bright Dec’16 Jun’17 K2 CCD module CCD K2 K2CCD module Faint Completeness K2 CCD module CCD K2 K2CCD module Dense fields Dense fields Reminder: What we want to address! (model) Not a good match in mass! Model shows too low masses! Mass (MSun) Radius (RSun) Sharma, Stello, Bland-Hawthorn et al. (2016) Is this mismatchDirect comparison because with Galaxy model of unknown selection effects OR because our galactic model is inadequate? Extremely important to understand. Otherwise we can not expect to make useful comparisons! K2-HERMES results! 2014 Fields Campaign 1 2015 Fields Campaign 17 Campaign 14 2016 Fields Campaign 10 2017 Fields Campaign 6 Campaign 16 2018 Fields Campaign 15 Campaign 5 Campaign 2 Campaign 18 Campaign 11 Campaign 0 Campaign 13 Campaign 9 Campaign 7 Campaign 4 Campaign 19 Campaign 3 Campaign 8 Campaign 12 Comparison with Galaxia & K2-HERMES C1 C6 C4 C7 High Lat. High Lat. Low Lat. Low Lat. K2-HERMES Old Galaxia model New Galaxia model Red Clump K2-HERMES Old Galaxia model New Galaxia model RGB Sharma, Stello, Bland-Hawthorn et al.
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