News from Germany

V2653 Ophiuchii with a pulsating component and Ppuls – Porb, Ppuls – g correlations for γ Dor type pulsators

“…The dominant pulsation periods are taken into account and the pulsation constants were calculated using these periods and mean densities. The pulsation constants vary between 0.17 and 0.72, systematically larger than the value of 0.033 days for the radial fundamental modes (Breger, 1990;Stankov& Handler, 2005).…”

High-resolution spectroscopy and abundance analysis of δ Scuti stars near the γ Doradus instability strip

“…The log g − P puls relation for pulsating stars has been known before (e.g. Claret et al 1990;Breger 1990;Liakos & Niarchos 2017). However, because our sample consists of stars in a narrow log g range, we did not find relations between P puls , Amp and log g. Similarly, no correlation between ξ and P puls was found for the analysed δ Sct stars.…”

“…The correlations between derived parameters and pulsation quantities were examined. As shown by Breger (1990), the P puls varies depending on the log g, T eff , and bolometric magnitudes. In our study, we found that a strong correla-tion between T eff and P puls exists.…”

“…Using the luminosity (L) -mass (M ) relation (L/L ⊙ ≈ M/M ⊙ ), the mean density (ρ ∼ M/R 3 ), and the pulsation constant (Q = P puls (ρ/ρ ⊙ ) 0.5 ), we can obtain that P puls ∝ (R/R ⊙ ) 0.5 (T eff / T eff ⊙ ) −2 . Breger (1990) also showed that the P puls depends on log g, T eff , and the bolometric magnitudes of pulsation stars. Balona & Dziembowski (2011) found similar relationships between P puls , Amp and T eff for δ Sct stars in the Kepler field.…”

“…As can be seen, there are no significant correlations between log g, P puls and Amp. On the other hand, Claret et al (1990) and Breger (1990) found a relation between P puls and log g. According to them, P puls decreases with increasing log g values. δ Sct stars in our study were selected considering their positions in the log g -log T eff di-agram.…”