29 frequencies for the δ Scuti variable BI CMi: the 1997–2000 multisite campaigns

A multisite campaign of BI CMi was carried out with excellent frequency resolution and high photometric accuracy from 1997 to 2000, including two long observing seasons. 29 pulsation frequencies could be extracted from the 1024 h (177 nights) of photometry used. The detected frequencies include 20 pulsation modes in the main pulsation frequency range from 4.8 to 13.0 cycle d⁻¹ (55 to 150 μHz), eight linear combinations of these frequencies, and a very low frequency at 1.66 cycle d⁻¹. Since the value of the low frequency at 1.66 cycle d⁻¹ cannot be identified with a linear combination of other frequencies, g-mode pulsation is suspected, but rotational modulation of abundance spots cannot be ruled out. BI CMi, which is situated near the cool edge of the classical instability strip, may be both a δ Scuti and a γ Doradus star. Another outstanding property of BI CMi is the presence of a number of close frequency pairs in the power spectrum with separations as small as 0.01 cycle d⁻¹.
A rotational velocity of     was determined from a high-dispersion spectrum. From phase differences, the dominant modes can be identified with ℓ values from 0 to 2. The spectral type and evolutionary status of BI CMi are examined.     

Relationship between low and high frequencies in the δ Scuti star KIC 9764965

Two years of Kepler spacecraft data of the δ Sct/γ Dor star KIC 9764965 revealed 67 statistically significant frequencies from 0.45 to 59.17 c d^–1 (0.005 to 0.685 mHz). The 19 low frequencies do not show equidistant period spacing predicted for gravity modes of successive radial order. We note a favored frequency spacing of 2.053 c d^–1 that appears in both the low‐frequency (gravity mode) region and high‐frequency (pressure mode) regions. The value of this frequency spacing also occurs as a dominant low frequency and in a high‐frequency triplet. A peak at exactly twice the value of the 2.053 cd^–1 mode is shown not to be a Fourier harmonic of the low‐frequency peak due to a different amplitude variability. This behavior is also seen in other δ Sct stars. The test for resonant mode coupling between low and high frequencies could not be carried out due to the small amplitudes of the peaks, making it difficult to separate the parent and child modes. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The δ Scuti star 38 o1 Eri

We present and discuss 247 high dispersion échelle spectra of the δ Scuti star 38 o ¹ Eri. We find at least three periods, but all are affected by aliasing problems. We attempt to identify the modes by a technique involving both temporal and spatial pre-whitening. All modes are of high degree, probably ℓ≈4 and ℓ≈7.     

2005 Photometric observations and multiple frequencies of the <Emphasis Type="Italic">δ</Emphasis> Scuti variable V350 Peg

We present the V light curves of δ Scuti type variable V350 Peg, obtained between August and October 2005 at the Ankara University Observatory (AUG) and the TüBíTAK National Observatory (TUG). By application of multiple-frequency analyses using Period04 to 7878 photometric V measurements (which are consist of our 747 V data and 7131 V data obtained at Monegrillo Observatory) of V350 Peg, a five-frequency solution was found to be fitted well to the data. In accordance with the computed Q values for V350 Peg, it was found that this star has probably radial mode with l=0 and g-mode oscillations.