Pulsations and magnetic activity Pulsations and magnetic activity in the IRin the IR

Rafa Garrido & Pedro J. AmadoRafa Garrido & Pedro J. Amado

Instituto de Astrofísica de Andalucía, CSIC. Instituto de Astrofísica de Andalucía, CSIC. GranadaGranada

tωie),(θY(r)f)t,θ,r,( n,lml

n,l,m

nlmp

p

Radial dependence (n)

Angular dependence (l,m)

Acoustic oscillations

Standard solar modelStandard solar model1996 standard solar model

inclusion of He settling& improved physics

base of convection zone

better physics for core needed

Standard solar modelStandard solar model

Differential rotationDifferential rotation

Small and large separationsSmall and large separationsSolar oscillations (VIRGO-SOHO)Solar oscillations (VIRGO-SOHO)

Asteroseismic diagram:J. C. Christensen-Daslgaard, Rev. Mod. Phys., 74, 1073

ScutiScuti DoradusDoradus

Variability ZooVariability Zoo

GiantsGiants

Hya

GSC 09137- 03505

UMa

Boo

LAST RESULTS WITH HARPSLAST RESULTS WITH HARPSB. Mosser (Corot week 6: May 2004, Orsay)B. Mosser (Corot week 6: May 2004, Orsay)

• A clear signature of the large separation :

89 Hz

HARPS PERFORMANCEHARPS PERFORMANCE

2 minutes integration time

for V=6 on the ESO 3.6m:

σv=1 ms-1 @ vsini= 0 kms-1

σv=3 ms-1 @ vsini=10 kms-1

5.15.05.0RV

RS

Benefits from the IRBenefits from the IR

Flux gainFlux gain

Benefits from the IRBenefits from the IR

magnetic sensitivitymagnetic sensitivity

ProblemsProblems TheoryTheory

mode selection (amplitudes)mode selection (amplitudes) amplitude & phase changesamplitude & phase changes input physics in modelsinput physics in models

convection & overshootingconvection & overshooting diffusion & settlingdiffusion & settling rotationrotation magnetic fieldmagnetic field

ObservationsObservations mode identification (spectroscopy & photometry)mode identification (spectroscopy & photometry) data analysisdata analysis

Active stars:Active stars:Science goalsScience goals

Dynamo geometryDynamo geometrySolar-like or something different?Solar-like or something different?Polar spots and active beltsPolar spots and active belts

Spot structureSpot structureResolved or not?Resolved or not?

Differential rotation and meridional flowsDifferential rotation and meridional flowsLifetimes of individual spots and active regions Lifetimes of individual spots and active regions Stellar “butterfly diagrams”Stellar “butterfly diagrams”Different stellar typesDifferent stellar types

Pre-main sequence starsPre-main sequence starsYoung main-sequence stars with[out] radiative Young main-sequence stars with[out] radiative

interiorsinteriorsSubgiants and giantsSubgiants and giants

Intensity

A A

Intensity

v sin i-v sin i v(spot) v sin i-v sin i v(spot)

Doppler ImagingDoppler Imaging

Data requirementsData requirements Time-series of hi-res (R > 30000) spectra:Time-series of hi-res (R > 30000) spectra:

Good supply of unblended intermediate-strength lines (!)Good supply of unblended intermediate-strength lines (!) Broad-band light-curves.Broad-band light-curves. TiO and other temperature diagnostics.TiO and other temperature diagnostics.

Least-Square DeconvolutionLeast-Square Deconvolution Assume observed spectrum = Assume observed spectrum = mean profile mean profile convolved with convolved with

depth-weighted line pattern:depth-weighted line pattern:

De-convolve De-convolve mean profile zmean profile zkk via least squares:via least squares:

S/N improves from ~100 to ~2500 per 3 km sS/N improves from ~100 to ~2500 per 3 km s–1 –1 pixel with pixel with ~2500 lines. ~2500 lines.

=

Mean profile, z

(UNKNOWN)

Depth-weighted line pattern, - KNOWN

Rotationally broadened spectrum, r – KNOWN

2

22

2

where,0:Solve

j j

kjkj

k

zr

z

DI MapsDI Maps

AB DorAB Dor

DI MapsDI Maps

VW CepVW Cep

ZDI MapsZDI Maps

AB DorAB Dor

Benefits from the IRBenefits from the IR

Spectral lines are less blended in the infrared. Hence, Spectral lines are less blended in the infrared. Hence, line profile variations are more clearly detectedline profile variations are more clearly detected

The Zeeman effect is enhanced for lines in the IRThe Zeeman effect is enhanced for lines in the IR Radiation flux and pulsation amplitudes increase with Radiation flux and pulsation amplitudes increase with

increasing wavelength for cooler stars.increasing wavelength for cooler stars. IR lines can probe different parts of the atmosphere.IR lines can probe different parts of the atmosphere.

2λ

Benefits from the IRBenefits from the IR

Sun continuum contrast between photosphere and Sun continuum contrast between photosphere and TTspot spot == 4250 K:4250 K: ≈ 20% @ 0.6 20% @ 0.6 µµmm ≈ 70% @ 2.2 70% @ 2.2 µµmm

Resolving the telluric absorption lines (intrinsically Resolving the telluric absorption lines (intrinsically narrow narrow ~5 km s~5 km s−1−1) ) Pontoppidan & van Dishoeck, 2004, astroph Pontoppidan & van Dishoeck, 2004, astroph 04056290405629

Zeeman sensitivity: the Fe I line at 1.56 Zeeman sensitivity: the Fe I line at 1.56 µµm m splits by splits by twice the FWHM in 1.5 kG fields (slowly rotating twice the FWHM in 1.5 kG fields (slowly rotating stars): 2-3 times more sensitive than optical lines stars): 2-3 times more sensitive than optical lines (Giampapa PASP 109)(Giampapa PASP 109)