The magnetic personalities of stars revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada Ap star impersonator B ≈ 500 G age ≈ 1 Gyr

The magnetic personalities of stars revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada CP2 star impersonator B ≈ 500 G age ≈ 1 Gyr CP2 = (Crazy Person) 2

The magnetic personalities of stars revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada Ap star impersonator B ≈ 300 G age ≈ 60 Myr

The magnetic personalities of stars revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada Ap star impersonator B ≈ 20 kG age ≈ 10 Gyr

Evolution of space telescopes HST

Evolution of space telescopes MOST HST to scale

“Suitcase” in space MOST HST

Happy Birthday! MOST HST 10 years in space! launched from Plesetsk 30 June 2013

Evolution of space telescopes MOST HST

Evolution of space telescopes MOST BRITE HST

Evolution of space telescopes MOST BRITE Constellation Canada 2 nanosats Austria 2 nanosats Poland 2 nanosats HST

Evolution of space telescopes MOST BRITE Constellation Canada 2 nanosats Austria 2 nanosats Poland 2 nanosats launch 25 Feb 2013

MOST BRITE Constellation Canada 2 nanosats Austria 2 nanosats Poland 2 nanosats launch 25 Feb 2013 Constellation Evolution of space telescopes

Constellation Car battery in space

HST MOST Evolution of space telescopes BRITE Constellation

MOST BRITE Constellation Evolution of stars HST “retired” A-type

MOST Evolution of stars HST K giant BRITE Constellation “retired” A-type

MOST Evolution of stars HST “retired” B-type BRITE Constellation

MOST BRITE Constellation Evolution of stars HST “retired” B-type rapid rotation + dense winds

MOST BRITE Constellation Evolution of stars HST “retired” B-type

MOST, CoRoT and Kepler give ultra-precision and are being joined by BRITE Constellation to extend coverage of stellar parameter space CoRoTBRITEMOST not to scale Kepler Photometry of stars from space

The magnetic personalities of stars revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada Ap star impersonator B ≈ 500 G age ≈ 1 Gyr

The nonmagnetic personality... of an A star revealed by MOST Jaymie Matthews Univ. of British Columbia Vancouver Canada David Mkrtichian National Astronomical Research Institute of Thailand

A bright, rapidly rotating A5 star (HD 15082) with a transiting gas giant planet in a 1.22-day retrograde orbit – 5.5 stellar radii from the star’s photosphere WASP-33 Trailed spectrum of rotation profile from the HERMES spectrograph (MERCATOR, La Palma) covering the transit on 26 October 2010 The longest high-resolution spectral time series of this system Several pulsation modes are seen Planet's spectral silhouette seen travelling in retrograde direction

A bright, rapidly rotating A5 star (HD 15082) with a transiting gas giant planet in a 1.22-day retrograde orbit – 5.5 stellar radii from the star’s photosphere WASP-33 Trailed spectrum of rotation profile from the HERMES spectrograph (MERCATOR, La Palma) covering the transit on 26 October 2010 The longest high-resolution spectral time series of this system Several pulsation modes are seen Planet's spectral silhouette seen travelling in retrograde direction

A bright, rapidly rotating A5 star (HD 15082) with a transiting gas giant planet in a 1.22-day retrograde orbit – 5.5 stellar radii from the star’s photosphere WASP-33 Trailed spectrum of rotation profile from the HERMES spectrograph (MERCATOR, La Palma) covering the transit on 26 October 2010 The longest high-resolution spectral time series of this system Several pulsation modes are seen Planet's spectral silhouette seen travelling in retrograde direction

MOST light curve observations over 24 days in October 2010 V = 8.3

Phased to the orbital period f = 9.84 cycles per day a = mag P = 1.22 day retrograde orbit

Pulsation frequencies hybrid?

The magnetic personalities of stars revealed by MOST

Target Type Main objective HR 1217 roAp asteroseismology γ Equ roAp asteroseismology 10 Aql roAp asteroseismology HD 9289 roAp asteroseismology HD roAp asteroseismology HD roAp asteroseismology σ Ori E B2Vpe wind physics HR 5907 B2Vpe wind physics exoplanet systems star-planet magnetospheric interactions MOST and magnetic stars

Target Type Main objective HR 1217 roAp asteroseismology γ Equ roAp asteroseismology 10 Aql roAp asteroseismology HD 9289 roAp asteroseismology HD roAp asteroseismology HD roAp asteroseismology σ Ori E B2Vpe wind physics HR 5907 B2Vpe wind physics exoplanet systems star-planet magnetospheric interactions MOST and magnetic stars

rapidly oscillating Ap discovered by Don Kurtz in 1978 ~45 members of the class periods: 6 ~ 21 minutes amplitudes: few mmag and less p-modes of low-degree, high-overtone global magnetic fields: B ~ kG roAp stars but see SuperWASP poster by Holdsworth & Smalley

models by Hideyuki Saio roAp stars freq. vs. T

models by Hideyuki Saio shaded region is where κ mechanism in H ionisation zone can excite high- order p-modes Z = 0.02 B polar = 0 He-depleted He I ionisation zone ℓ = 1 modes boundary condition at log τ = −6 running wave for ω > ω c roAp stars excitation

models by Hideyuki Saio shaded region is where κ mechanism in H ionisation zone can excite high- order p-modes The preliminary models suggest that a mechanism other than H ionisation is needed to excite most roAp pulsations roAp stars excitation

ν1 – ν6 MOST photometry Michael Gruberbauer (Mk1 – 1 c/d); Mk2 radial velocity data David Mkrtichian gamma Equulei echelle diagram of modes roAp stars excitation

ν1 – ν6 MOST photometry Michael Gruberbauer (Mk1 – 1 c/d); Mk2 radial velocity data David Mkrtichian Model frequencies agree with observation but none are excited gamma Equulei roAp stars excitation echelle diagram of modes

Target Type Main objective HR 1217 roAp asteroseismology γ Equ roAp asteroseismology 10 Aql roAp asteroseismology HD 9289 roAp asteroseismology HD roAp asteroseismology HD roAp asteroseismology σ Ori E B2Vpe wind physics HR 5907 B2Vpe wind physics exoplanet systems star-planet magnetospheric interactions MOST and magnetic stars

residuals spectral window 50 µmag Kurtz et al. 2002, MNRAS 330, L57 Kurtz, Cameron et al. 2005, MNRAS  rapidly oscillating Ap star periods near 6 min 0 < B field < 1.2 kG P = (16) d discovered by Kurtz (1982) Ryabchikova et al. (2005) rot Rich p-mode spectrum  6 dominant modes + 1 anomalous one window HR 1217 = HD WET campaign p-modes in magnetic stars

HR 1217 Chris Cameron PhD thesis, 2010, UBC 3 gaps due to charged particle hits 12.5 d = P rot’n MOST photometry Nov-Dec hr over 29 days duty cycle = 96% 30-sec integrations custom optical filter p-modes in magnetic stars 2004 MOST campaign

34 frequencies p-modes in magnetic stars HR 1217

10 5 YREC models Yale Rotating Evolution Code M = 1.3 → 1.8 M ʘ in steps of 0.05 M ʘ Z = → in steps of X = 0.70, 0,72, models in error box used for pulsation modeling values of large frequency spacing Δν Z ↑ X ↑ α = 1.4, 1.6, 1.8

HR 1217 small spacings of models observed small spacing ~ 2.5 μHz This value consistent with models of low metallicity Z < 0.01 mass M ~ 1.5 M ʘ age t > 1 Gyr p-modes in magnetic stars

Kurtz 1982 MNRAS 200, 807 pulsation amplitudes & phases modulated with magnetic (= rotation) period Oblique Pulsator Model Magnetoasteroseismology

Cunha & Gough 2002 Bigot & Dziembowski 2002, A&A 391, 235 Kurtz 1982 MNRAS 200, 807 Cunha 2006 Dziembowski & Goode 1996 Saio & Gautschy 2004, Saio 2005 eigenfunction expanded with Y ℓ m (θ, φ) variational principle and WKB approximation including rotation pulsation amplitudes & phases modulated with magnetic (= rotation) period Oblique Pulsator Model magneto-acoustic coupling Magnetoasteroseismology

magnetic slow wave acoustic wave phase difference  surface v A > c s v A << c s 0.95 R δP = 0× B’ = 0 ∆  Magnetoasteroseismology

Re ( shift ) Jumps in frequency depend on model structure and on pulsation mode & magnetic field geometries Cunha 2006 Magnetoasteroseismology

Saio Expands magnetic contribution to hydrostatic equation in spherical harmonics Cunha Estimates magnetic contribution via a variational principle Qualitative agreement between both approaches Magnetoasteroseismology

Magnetic fields shift pulsation frequencies The frequency shift changes depending on the structure of the stellar envelope Magnetic fields tend to damp pulsations This effect seems strong enough to damp low-overtone p-modes in roAp stars Magnetic fields modify the latitudinal distribution of pulsation amplitude Amplitude confined to polar regions, as in HR 3831 Theoretical models for Przybylski's Star, γ Equ, and 10 Aql agree with observed frequencies but required B p might be too big Magnetoasteroseismology

HR 1217 models of magnetic perturbations M = 1.7 M  M = 1.6 M  B = 10 kG B = 5 kG B = 1 kG log L/L ʘ → frequency shift → Magnetoasteroseismology

HR 1217 νB 0.75 frequency realimaginary shifts Frequency perturbations are cyclic 52,000 magnetic dipole models in grid B = 1 → 10 kG (steps of 0.1 kG) Magnetoasteroseismology

HR 1217 Only half of 52,000..models match even..only one frequency Only 0.5% of models..have a fit probability..within a factor of 100..of the model with the..highest probability → only a few × 100 …...models give a …..“good” match A magnetohydrodynamic lab

HR 1217 Magnetic fields essential to model observed very rich roAp eigenspectra … but parameter space is very complex with many local false minima Interpolations of limited model grids are dangerous A magnetohydrodynamic lab

What if there are no p-modes? his pet puppy “Spot”? Luis Balona Luis’ dream woman ???????? next to Mrs. Balona

MOST photometry Rotational modulation of spots

rapidly oscillating Ap discovered by Don Kurtz in 1978 ~45 members of the class periods: 6 ~ 21 minutes amplitudes: few mmag and less p-modes of low-degree, high-overtone global magnetic fields: B ~ kG roAp stars but see SuperWASP poster by Holdsworth & Smalley

He-strong stars with magnetospheric winds ~40 members of the class include HR 7355, HR 5907 delta Ori C, sigma Ori E variability in photometric indices Hα and radio emission UV wind absorption lines linear continuum & circular line polarisation massive magnetic fast rotators

Magnetospheres of OB stars magnetic OB stars → structured magnetospheres interaction between B field & radiatively-driven winds → wind confinement and rotation systematic investigation optical, UV, X-ray observations 2D and 3D, static and dynamic models highly precise photometry constrains rotation period, geometry rotational evolution (braking) plasma density and distribution Gregg Wade RMC Canada massive magnetic fast rotators

Magnetospheres of OB stars Rigidly-Rotating Magnetosphere model of σ Ori E massive magnetic fast rotators Recall Zdenek Mikulasek’s talk this morning Rich Townsend Wisconsin.

σ Ori E B2Vpe vsini ~ 165 km/s P rot ~ d M star ~ 7 M ʘ B dipole ~ 11 kG magnetic He-strong star rotation period is gradually lengthening due to magnetic braking Townsend et al variability originates from a combination of surface abundance inhomogeneities and wind-originated plasma trapped in a circumstellar, co-rotating, Townsend et al centrifugally supported magnetosphere massive magnetic fast rotators

Ω rotation frequency

σ Ori E Ω rotation frequency

MOST and magnetic stars Target Type Main objective HR 1217 roAp asteroseismology γ Equ roAp asteroseismology 10 Aql roAp asteroseismology HD 9289 roAp asteroseismology HD roAp asteroseismology HD roAp asteroseismology σ Ori E B2Vpe wind physics HR 5907 B2Vpe wind physics exoplanet systems star-planet magnetospheric interactions

σ Ori E 21 days of MOST photometry in Nov – Dec 2007 → 21 rotations massive magnetic fast rotators

σ Ori E massive magnetic fast rotators New rotation period ± d matches ephemeris – confirming that star’s rotation is slowing due to magnetic braking 21 days of MOST photometry in Nov – Dec 2007 → 21 rotations

σ Ori E massive magnetic fast rotators Townsend & Owocki (2005) proposed “breakouts” → stress on and eventual breaking of magnetic loops by centrifugal force, growing in strength as plasma accumulates MHD simulations by Owocki (2007) showing logarithmic density and temperature T in a meridional plane. The darkest areas represent gas with T ~ 10 7 K, hot enough to produce relatively hard X-ray emission (few keV)

σ Ori E massive magnetic fast rotators Townsend & Owocki (2005) proposed “breakouts” → stress on and eventual breaking of magnetic loops by centrifugal force, growing in strength as plasma accumulates MHD simulations by ud-Doula et al. (2006) also supported this centrifugal breakout hypothesis, suggesting that reconnection heating from breakout episodes could explain the X-ray flares seen in σ Ori E ( Groote & Schmitt 2004 & Sanz-Forcada et al ) Sharp changes n the light curve from rotational cycle to cycle were predicted from such centrifugal breakout episodes

σ Ori E 21 days of MOST photometry in Nov – Dec 2007 massive magnetic fast rotators Analyses of depths of light curve minima and residuals show no evidence for abrupt centrifugal breakout of plasma from the magnetosphere depths of primary (filled symbols) and secondary (open symbols) minima as a function of time

σ Ori E massive magnetic fast rotators Analyses of depths of light curve minima and residuals show no evidence for abrupt centrifugal breakout of plasma from the magnetosphere Together with a demonstration that the mass in the magnetosphere is 100 times less than the theoretical asymptotic mass, these findings suggest that breakout episodes do not play a major role in setting a star’s magnetospheric mass budget Townsend & Owocki (2005) proposed “breakouts” → stress on and eventual breaking of magnetic loops by centrifugal force, growing in strength as plasma accumulates

Ω rotation frequency

HR 5907 Ω rotation frequency

HR 5907 B2Vpe vsini ~ 280 km/s P rot ~ d R Keplerian ~ 1.4 R star R Alfven ~ 32 R star B dipole ~ 12 – 17 kG the most rapidly rotating known magnetic star discovered in 2010 by the MiMeS collaboration (Magnetism in Massive Stars) Grunhut et al massive magnetic fast rotators

HR 5907 observed by MOST during April/May 2011 for 18 days ≈ 35 rotations 11 rotations massive magnetic fast rotators

HR 5907 phase diagram 1σ error bars 0.01 cycle bins red squares Hipparcos measurements rescaled to MOST fluxes massive magnetic fast rotators

Magnetohydrodynamic labs sigma Ori E HR 5907

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