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

Molnár LászlóHungarian CoRoT Day

Budapest 2007

HD 44195

Secondary COROT target on the field of HD 43587 (Anticenter Direction)

Possible hybrid star δ Sct and γ Dor pulsation

Strong constraints on stellar structure models

Sp: F0, unenvolved mV = 7.56 mag

Hybrid stars

HD 44195

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)

δ Scuti stars

γ Dor stars

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. 2005 AJ, 129, 2461

Hungarian observations

1 m RCC telescope

2006 winter 8 nights, 39.4 hours

2007 winter 3 nights, 11 hours

The γ Doradus frequencies

Poor sample

Solutions with 2 frequencies:

1

2

3

1.15 c/d 20 mmag 2.31 c/d 10 mmag

1.20 c/d 9 mmag 1.33 c/d 11 mmag

0.71 c/d 16 mmag 1.23 c/d 7 mmag

δ Scuti frequencies

2006 winter data:

Changes to Poretti

et al.’s frequencies

Frequency (c/d) Ampl. (mmag)

20.48 2.3

11.40 2.1

15.37 1.4

δ Scuti frequencies

All data Strong alias structure

Further changes?

Frequency (c/d) Ampl. (mmag)

11.35 2.5

15.32 1.5

20.48 1.9

Hungarian vs. COROT data

Artificial data: 150 days long, no noise

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!

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)

HD 172189

We have not observed eclipses Good agreement with the lightcurve

Thank you for your attention