Probing Stellar Physics and Testing Stellar Evolution through Asteroseismology

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A proposal submitted in February 2008...

Judged to be high-risk high-gain...

Our tasks and promised deliverables • WP1: Determine core overshoot

parameter of OB stars• WP2: Determine internal rotation of

OB stars and of red giants• WP3: Perform asteroseismology in

upper HRD• WP4: Determine internal angular

momentum of red giants• WP5: Make better theoretical models for

subdwarf B stars from asteroseismology + build multi-colour camera MAIA@Mercator: Steven Bloemen

• WP6: automated classification of variable stars of CoRoT and Kepler LCs

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Between Submission & Implementation

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De Ridder et al. (2009) cheerful Joris in Nov.2008

Tim’s excellent review and recap of the

history of RG asteroseismology:

prize for best effort in

explaining complicated physics in a simple

way

Story and enthousiasm looked familiar...

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Tim’s review:De Ridder et al. (2009)

cheerful Joris in Nov.2008

Konstanze Zwintz: equally joyful that she’s finally getting

there with “her” pre-MS pulsators...

WP1: core overshoot of OB stars

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(1) Aerts et al. (2006); (2) Pamyatnykh et al. (2004); (3) Mazumdar et al. (2006); (4) Briquet et al. (2011); (5) Dupret et al. (2004); (6) Briquet et al. (2012); (7) Aerts et al. (2011); (8) Desmet et al. (2009); (9) Degroote et al. (2010); (10) Walczak et al. (2013);"(11) Briquet et al. (2007).

Staritsin (2013): 3D HD simulations

of turbulent entrainment in near-core regions,

following Arnett & Meakin (2009)

Most successful stories on Asteroseismology with CoRoT and Kepler: the winner is.... Red Giants....

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says an OB star fan...

Cf. Miglio et al., Basu et al., Hekker et al., Stello et al., Corsaro et al., Silva et al.,...

Dipole mixed modes Evolutionary status

Internal rotationGalactic Structure Galactic Ageing

Seismic distances (Lars Task 1:

calibrate prior to Gaia!)Seismic limits on RGB mass loss

Scaling relations up to M supergiants

WP2+WP4: Internal rotation & AM of red giants

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(1) Beck et al. (2012); (2) Deheuvels et al. (2012); (3) Mosser et al. (2012, 2013); (4) Eggenberger et al. (2012); (5) Goupil et al. (2013), (6) Ouazzani et al. (2013); (7) Marques et al. (2013),... & many others... among whom Mathieu & Mathieu: theoretical interpretation of fine structure

Beck et al. (2012, 2014) as part of PROSPERITY PhD Thesis (public defence: Friday!): detection and interpretation of rotational splitting

of mixed dipole modes in single + binary red giants: core some 10-15 times faster than envelope

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KIC 6928997: rotationally unaffected

KIC 8366239: rotational splitting of some 0.15µHz

Tasks: Internal rotation & AM transport in red giants

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""Lars Task 2: can we detect contracting RG after shut down of H-shell burning(lasts 10000 years)?""Lars Task 3: can we detect signature of relic layer which creates two regions inside RG pulsators in early red clump phase?""Consensus: Core rotation rates “only” some 10 to 15 faster than envelope: serious lack of coupling between core and envelope (cf. also Lars, presenting Matteo’s results)

Cf. Steve’s review “happens prior to AGB, not at later phases!...” from seismically deduced rotation periods of pulsating sdBs & WDs Task Conny to binary evolution experts: RG eccentric binaries seem to have similar core/envelope rotation ratios as single RGs; does this hold higher upon RGB?

WP5: better models for sdB stars• Inclusion of gravitational

settling, concentration &thermal diffusion+radiative levitation by solving diffusion equations for H,He,C,N,O,Ne,Mg,Fe,Nialong evolution with STARS (Eggleton) code + coupled to MAD (Dupret) code by Hu et al. (2009,2011,2012):excitation of g-modes at observed Teff for one track

• Bloemen et al. (2013), as part of PROSPERITY PhD Thesis: computation of new IS strip, with or without some mixing: blue edge problem solved! (but what about binary evolution properties - Bert?)

• Meanwhile, codes by Haili Hu have been included in MESA code by Bill Paxton et al., so community can use that new input physics

👍😰

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😰

WP6+WP2: internal rotation of stars

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• Cf. Talk Coralie Neiner (and my sincere apologies that I missed 5 talks on B stars due to hospital visit....): several interesting detections in rapidly rotating B pulsators, but tough to model... • A lot of work needed to interpret diverse variability of OB stars • Detailed case studies of 9 B-type pulsators from GO programme: Peter Pápics et al. (2013 + ongoing) ...results coming soon... • Theoretical studies: ongoing (Saio et al., Rieutord et al., Reese et al.,...) For slow B-type rotators so far: core rotation a few times envelope rotation. Is this also true of rapid rotators?

• Do not underestimate the importance of IGW in AM (S. Mathis) + chemical transport ? (cf. talk Norbert: N abundances in OB stars)

WP3: Asteroseismology in upper HRD: hard!...

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Heat-driven gravity modesHeat-driven pressure modesStochastically-excited modes

Rotational modulationChemical inhomogeneities

Radiation-driven wind variabilityMagnetically-induced “granulation”

Tidally-induced pulsations...

§ Cantiello et al. 2009,2010; Cantiello & Braithwaite 2011

X,Z,M, τ,αov

STELLAR MODEL FOR SPECIFIED INPUT PHYSICS

THEORETICAL PULSATION MODE

PROPERTIES

TIME SERIES OBSERVATIONS

OBSERVED PULSATION MODE

PROPERTIES

χ2

STELLAR EVOLUTION

CODE

PULSATION CODE

MODE IDENTIFICATION

FREQUENCY ANALYSIS

Coming soon: observational

variability of large sample of OB stars

(S. Simon-Diaz et al.)

Major emphasis on input physics of OB stars is necessary in coming years

WP3: Asteroseismology in upper HRD: hard!...

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X,Z,M, τ,αov

STELLAR MODEL FOR SPECIFIED INPUT PHYSICS

THEORETICAL PULSATION MODE

PROPERTIES

TIME SERIES OBSERVATIONS

OBSERVED PULSATION MODE

PROPERTIES

χ2

STELLAR EVOLUTION

CODE

PULSATION CODE

MODE IDENTIFICATION

FREQUENCY ANALYSIS

Ehsan Moravveji: theoretical

interpretation in terms of core overshoot,

semiconvection, rotational mixing, mode excitation & opacities, radiation-driven

wind?...+ pulsational signatures of all these

phenomenaKiel diagram

Startingpoint for SN

computations

What we did not (yet) look into

• Asteroseismology of exoplanet hosts: • JCD, Jason Rowe: deliver M, R, age, far better than any other

method: can have quite an impact on planetary radii • Be careful: exoplanets not only have mean density, but

atmosphere; host star variability has big impact on atmospheric properties (Heike, Leen, Valerie)

• Effects of magnetic fields on OB star pulsations (g modes)and on solar-type stars? (inclusive of flaring, activity,... (Rafa Garcia, Tom Vandoorsselaere)

• Implications/Gain of having Gaia distances on OB star seismic modelling

• Can we give seismic information on the last stages of massive star evolution? WR stars (Tony Moffat); Supernovae progenitors (Thomas Janka)

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Probing Stellar Physics and Testing Stellar Evolution through Asteroseismology

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Was not that risky after all, and

certainly worthwhile!...

A SWOT analysis of asteroseismology

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Asteroseismology: SWOT

•S:• Only direct observational probe of stellar interiors: frequencies are mainly

determined by interior physics• MOST, CoRoT, Kepler provided appropriate data for thousands of stars,

in many evolutionary stages, including binary pulsators: birth of tidal asterseismology

• The best is yet to come, focus has been on scaling relations & follow-up spectroscopy but hardly on deep seismic interpretation individual stars = next step now that the Kepler time series are as complete as possible

•W: • We still use classical input: Teff, log g, surface abundances:

Gaia distances and/or EB are assets • Mode identification = biggest stumbling block for heat-driven pulsators

without frequency or period patterns• Asteroseismologists give too technical talks at general conferences!....

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Asteroseismology: SWOT

•O:• Use asteroseismic constraints/diagnostics to improve stellar evolution

computations in localised areas, e.g., 3D description of near-core regions of massive stars, outer Fe/Ni opacity bump zones in massive stars: needs better interactions between two quite separate communities

• exploit fully acoustic glitches and deviations from uniform period spacings• improve treatment of angular momentum transport and mixing • Kepler2.0 (don’t wait too long!); TESS, PLATO

•T: • CoRoT and Kepler are both dead....we shall not get longer time series • asteroseismology was mainly observationally driven the past decade;

improvements in oscillation theory and in stellar models are needed but require a switch of expertise from observational and data-driven analyses to theory: long-term research investments are required!

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Thanks, thanks, many thanks "to the Francqui Foundation for the great honours I receive since May 2012 and for the generous support which made this symposium possible, as well as the friendship "to all my sponsors since my PhD defence (exactly 20 years ago...) "

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• To all speakers, for making this an interesting symposium and for delivering their slides (don’t forget!) • To all invited speakers, for being prepared to broaden the horizons of us participants of this short symposium • To all session chairs, for their original and interesting ideas about my injury • To Andrew, for taking care of all the IT aspects of the presentations • To Peter & Steven, as photographers on duty • To the IvS crew for taking care of the microphones during the questions • To Katrijn and Martine for the entire practical organisation of this meeting • To the University Foundation, for the catering and service

Have a safe trip back home