Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 1

Hommage to Hommage to Henrietta Leavitt Henrietta Leavitt from the CoRoT Teamfrom the CoRoT Team

1908

2008

Annie BAGLIN, Merième CHADID, Zoltan KOLLATH, Michel AUVERGNE

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 2

A stellar photometer in A stellar photometer in spacespace

* Ultra high relative photometry 100 to 1000 times more accurate than from ground

•Very long continuous durationsMore than 150 days

Dedicated to time variability from minutes to monthsDedicated to time variability from minutes to months

The CoRot product : Light curves

For 679 days in orbit

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 3

The focal planeThe focal plane

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1.3 °

field of view

Seismology field highly defocussed

main target (≤ 6)

12000 targetssampling 8.5 min (32 s.)

secondary targets (≤ 9)

10 targetssampling 1 s to 32s

Exoplanet fieldOn focus + bi-prism

faint stars (11-16)

Aperture photometry on selected targets to reduce the TM flow

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 4

Seismology Targets Seismology Targets already observedalready observed

6 Delta Scuti, 2 known gam Dor

10 B stars, Beta Ceph,

3 Be

10 giants (G,F)

14 A/early F stars ?2 Am, 7 Ap,

9 solar-like puls. cand.

(one observed twice)The classical HR diagram and the known class of variables

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 5

Solar like starsSolar like stars

6th mag

White noise

granulation

oscillations Eric Michel andThe SWG

Detection and measurement of oscillations and granulation in several stars

First interpretations show the presence of unexpected mechanisms of mixing in the stellar core

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 6

The Instability StripThe Instability Strip

Cepheids

RRLyrae

Delta ScutiDelta Scutis

in the seismology field high accuracy

Large number of modes ?

RR Lyrae

Continuous, ampl variations

Blasko effect

CepheidsLow amplitudesDouble modesStrange modes?

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 7

Delta scuti starsDelta scuti stars

2 days 2 days

2 days 3 days

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 8

In delta scuti stars A very rich In delta scuti stars A very rich spectrumspectrum

Eric Michel and the SWG

Ground based observations

The zoom below shows for the delat scuti star a very rich signal absent in another target of the same magnitude

This signal is real…..needs interpretation….not easy!

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 9

NGC2264 CCD E1

Seismology, variability Seismology, variability in the exoplanet fieldin the exoplanet field

*Data collected for the exoplanet search, R< 16, ~5500 stars per CCDPresently ~ 88 000 observed

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 10

Variables are everywhereVariables are everywhere

40%variables

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 11

Automatic classificationAutomatic classification

29 classes

Being Improved

…..

•4 first runs •IRa01, SRc01, LRc01, LRa01• 200 SPB• 190 Beta Cephei• 32 Dor• 1230 Delta Scuti• 8 RR Lyrae• 10 classical cepheids, 2 double mode• 5800 low amplitude Cepheids ?

A lot of uncertianties• New classes?

Debosscher et al.,

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 12

RR Lyrae: RRab with Blashko RR Lyrae: RRab with Blashko effecteffect

150 days

M. Chadid et al.

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 13

The Blazhko frequencyThe Blazhko frequency

Blazhko frequency

0.0369 c/d (27.1003 d)

and its harmonic 0.0746 c/d

For the first time

the Blazhko frequency is directly

measured in the Fourier spectrum.

The Blazhko effect reduces

the amplitude by over 50%.

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 14

First detection of an overtoneFirst detection of an overtone

For the first time in a RR ab star,

additional mode: at 4.0323 c/d

and half of it: 2.0162

with harmonics up to 5thharmonic.

Ratio to the fundamental frequency is 0.7177.

fundamental and first overtone double mode

pulsator...

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 15

Classical CepheidsClassical Cepheids

Rare objects but several (10) detections in the exo field

Amplitude (mag) 0.1Period (days) 30

Amplitude 0.5Period 6

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 16

Smaller and smaller?Smaller and smaller?

Amplitude 0.035Period 6

Amplitude 0.03Period 1.6

Amplitude 0.02Period 5

Amplitude 0.02Period 1.2

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 17

Probably a binary…..Probably a binary…..

Sometimes curious objects, be cautiousThe two very small repeating spikes in phase cast doubts on the pulsation nature of the variationOnly a very small sampling can reveal that as they last oy 4 hours

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 18

Strange Cepheids in the Strange Cepheids in the CoRoT targetsCoRoT targets

There seem to be CoRTt variables in the predicted domain of strange modesGround base observation are in progress to obtain precise stellar parameters

(Zoltan Kollath et al.)

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 19

A Double mode cepheidA Double mode cepheid

f1: 0.778 c/dF2: 0.971 c/d

More candidates….

More candidates to come…..

Thanks to Henrietta Swan Leavitt, Harvard CfA November 5th 2008 20