Download - Magnetic activity of F stars
![Page 1: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/1.jpg)
Magnetic activity of F stars
Savita MathurSpace Science Institute
![Page 2: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/2.jpg)
Sunspot number
[García et al. 2010][Salabert et al. 2009]
VIRGO/SPM VIRGO/SPM
[Mathur et al. 2013]
Magnetic activity: photometry
APS colloquium 2014 2
![Page 3: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/3.jpg)
APS colloquium 2014
The CoRoT target: HD49933 Stellar parameters:
– F5V dwarf • 1.2 M; 1.3 R
– Observed by CoRoT during 60 + 137 days + 90 days• 50 oscillation modes
measured
– Prot = 3.4 days
[Appourchaux et al. 2008; Benomar et al. 2009]
//
//
//
//
3
![Page 4: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/4.jpg)
Hints of a magnetic-activity cycle
Anticorrelation between amplitude variation and frequency shiftsPcyc>120days
[García et al. 2010]
Seismology Spectroscopy
Complementary observations Ca HK: Mount Wilson index of 0.31
Active star
HD49933
APS colloquium 2014 4
![Page 5: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/5.jpg)
Coming back to surface rotation
[Garcia et al. in preparation]
HD49933
APS colloquium 2014 5
Prot<12d
[García et al. in prep.]
![Page 6: Magnetic activity of F stars](https://reader036.vdocuments.mx/reader036/viewer/2022062321/56812ad3550346895d8eb3dd/html5/thumbnails/6.jpg)
Results: KeplerShere-KhanProt=2.5d
<Sph> = 250 ppm
Asteroseismology:M~1.4M
DCZ~3%
[Mathur et al. 2014, in press] APS colloquium 2014 6
We observe: Magnetic Cycle-like behaviour Long-lived active longitudes during
maximum activity