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HD 44195: a hybrid star with Delta Scuti and Gamma Doradus character

Study on HD 44195, a possible hybrid star exhibiting both δ Scuti (low-order p-mode) and γ Doradus (high-order g-mode) pulsations. Strong constraints on stellar structure models. Comparison of Hungarian and COROT observations.

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HD 44195: a hybrid star with Delta Scuti and Gamma Doradus character

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  1. HD 44195: a hybrid star withDelta Scuti and Gamma Doradus character Molnár László Hungarian CoRoT Day Budapest 2007

  2. Secondary COROT target on the field of HD43587(Anticenter Direction) Possible hybrid star δ Sct and γ Dor pulsation Strong constraints on stellar structure models Sp: F0, unenvolved mV = 7.56 mag HD 44195

  3. δ Sct: low-order p-mode pulsations (κ-mechanism) γ Dor: high-order g-mode pulsations (convective blocking) other hybrid stars: HD 209295(?), HD 8801 BD+18 4914, HD 114839 (MOST) Hybrid stars δ Scuti stars γ Dor stars HD 44195

  4. Previous observations 2003 nov. 2005.jan. f < 5c/d f < 5c/d γ Dor γ Dor f = 20.5 c/d f = 20.5 c/d δ Sct δ Sct Poretti et al. 2005AJ, 129, 2461

  5. 1 m RCC telescope 2006 winter 8 nights, 39.4 hours 2007 winter 3 nights, 11 hours Hungarian observations

  6. The γ Doradus frequencies • Poor sample • Solutions with • 2 frequencies: • 1 • 2 • 3

  7. δ Scuti frequencies • 2006 winter data: • Changes to Poretti et al.’s frequencies

  8. δ Scuti frequencies • All data • Strong alias structure • Further changes?

  9. Hungarian vs. COROT data • Artificial data: 150 days long, no noise

  10. HD44195 - Summary • HD 44195 shows both γ Dor and δ Sct type frequencies • γ Doradus: at least 2 frequencies under 3 c/d • δ Scuti: F1 = 20.5 c/d, F2 = 11.4 c/d, F3 = 15.3 c/d • Possible changes? • COROT will find out!

  11. HD 172189 • Eclipsing and spectroscopic binary (P=5.7 days) • Delta Scuti component • 3 frequencies around 18-19 c/d • secondary target • Hungarian observations: 2 nights (2006 summer)

  12. HD 172189 • We have not observed eclipses • Good agreement with the lightcurve

  13. Thank you for your attention

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