Volume 570, October 2014
|Number of page(s)||20|
|Section||Stellar structure and evolution|
|Published online||03 November 2014|
Frequency table of the newly discovered CoRoT RRab star, 488.
Table A.1 contains the frequencies that we found during the frequency analysis. The star pulsates with a period of 0.485299 days. The following epoch for maxima was found: (A.1)Digits in parentheses denote the uncertainties. Nine harmonics can be found in the frequency spectrum. No additional frequencies were found.
Frequency table of the unmodulated CoRoT RRab star, 818.
Table B.1 enumerates the frequencies of the unmodulated RR Lyrae, 818. The period of this star is 0.4659348 days. No modulation was found in this RRab star. We found the following epoch for maxima: (B.1)After prewhitening, “forests” of peaks remain around the harmonics. These do not show any obvious modulation pattern, so we decided not to list them in Table B.1.
In Table C.1 we give the frequency content of 804. The star pulsates with a period of 0.7218221 days. No signs of modulation or additional frequencies were found in this object. The following epoch for maxima was obtained: (C.1)
Frequency table of the non-modulated CoRoT RRab star, 804.
In Table. D.1 we present the result of the Fourier analysis of the blended CoRoT Blazhko RRab star, 648. The following epoch for maxima was found: (D.1)
Frequency table of the blended Blazhko RRab star, 648.
This is a heavily blended Blazhko RRab star. The spectrum shows the frequency corresponding to the fundamental mode pulsation (f0) and nine harmonics. In addition, the right components of the modulation triplets are seen prominently around the harmonics after prewhitening. In a few cases, the left hand side peaks are also detected. The remaining spectrum consists of the known orbital frequencies of CoRoT, their linear combinations with the sideral day, many peaks due to low-frequency variations in the frequency interval 0.1−0.7 d-1, and some residuals around the main frequency and around the low-order harmonics. The residual peaks are at the level of 73 μmag. The amplitude and frequency variation of the star due to the Blazhko-modulation was already presented in Szabó et al. (2009).
Table E.1 lists the result of the Fourier analysis of the second blended CoRoT Blazhko RRab star, 544. This object was observed in the color mode of CoRoT, but we chose to present the co-added (white) light frequencies, because this data set is superior to the individual color observations. The following epoch for maxima was found: (E.1)
Frequency table of the white band light curve of the blended Blazhko RRab star, 544.
Despite the heavy blending, the spectrum shows the frequency corresponding to the fundamental mode pulsation (f0), and ten harmonics. In addition, the triplet components of the modulation found around f0 are revealed around most of the harmonics after pre-whitening. The right side-lobes (k ∗ f0 + fm) are present with higher amplitudes than their left hand counterparts. The remaining spectrum consists of the known orbital frequencies of CoRoT, and their linear combinations with the sideral day, many peaks due to low-frequency variations in the frequency interval 0.2−0.8 d-1, some residuals around the main frequency and low-order harmonics, and a few remaining peaks close to or below the significance level between f0 and 2f0. The residual peaks are at the level of 28 μmag. The amplitude and frequency variation due to the Blazhko-modulation was presented in Szabó et al. (2009).
Frequency table of the CoRoT RRc star, 241.
Besides the dominant first overtone frequency (f1 = 2.68153 d-1) and its harmonics, we see f′ in the spectrum with a characteristic 0.613 frequency ratio with the first-overtone
radial pulsation (Table F.1). In addition, several frequencies were found in the [0.5; 1.5] d-1 frequency range. Upon inspecting the data, we found that their origin can be traced back to two remaining discontinuities, therefore these portions of the data set CJD [3046.0−3048.0] and [3156.5−3157.5] were removed. In the following we analyze the remaining data set.
We found high left-hand side peaks around the main frequency and its harmonics. If we suppose that fm = 0.00585 d-1 is a modulation frequency, the period of the modulation would be longer than the data set. According to that this star may show a long-period Blazhko-modulation, but more data would be needed to confirm this finding. Another set of modulation-like frequency difference appears in the data set (Fig. 13, Table F.1). We denote the corresponding frequency fb. Neither fm, nor fb can be found in the frequency spectrum, but they only appear through combination frequencies. Even combination frequencies involving both fm and fb can be identified. We note here that as we demonstrated in Sect. 4.3, f′ has temporal amplitude variation, and this is the most probable culprit causing the appearance of the fb modulation frequencies. The strongest argument favoring this scenario is that fb appears only close to and in combination with f′, and is not seen around the main pulsation frequency, f1. In addition, frequencies associated with the orbital period of the satellite and its daily aliases are seen at f = 13.967924,14.974027,12.969585 d-1 as usual in CoRoT data. We omitted these peaks from Table F.1. The following epoch for maxima was found: (F.1)or taking a gradual period change into account: (F.2)
We detect the main frequency f1 = 3.58218 d-1 and its harmonics, but also many other frequencies with lower amplitude. Among them we found a highly significant frequency at f′ = 5.82484 d-1 with several peaks around it, then additional peaks around f1. The frequencies are available in Table G.1. The following epoch for maxima and period were found: (G.1)After prewhitening with the frequencies enumerated in Table G.1, a dense forest of frequencies remains around f1. We also see similar residual power around the second and third harmonics, frequencies around 5.9,9.4,16.5,20.1 d-1, and frequencies related to the orbital frequency of CoRoT.
The large number of side frequencies seen around frequencies f′ and 9.470874 d-1 may be the result of their non-stationary nature (modulation). We gave an example in Szabó et al. (2010) where the frequency forest found around the the half-integer frequencies was modeled and explained by the varying amplitude of these frequencies. We see a very similar situation here.
Frequency table of the CoRoT RRc star, 652.
© ESO, 2014
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