J/MNRAS/453/2022 Double-mode radial-non-radial RR Lyrae stars (Netzel+, 2015)
Double-mode radial-non-radial RR Lyrae stars.
OGLE-IV photometry of two high cadence fields in the Galactic bulge.
Netzel H., Smolec R., Moskalik P.
<Mon. Not. R. Astron. Soc., 453, 2022-2035 (2015)>
=2015MNRAS.453.2022N 2015MNRAS.453.2022N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Milky Way
Keywords: stars: horizontal branch - stars: oscillations -
stars: variables: RR Lyrae
Abstract:
We analyse the OGLE-IV photometry of the first overtone and
double-mode RR Lyrae stars (RRc/RRd) in the two fields towards the
Galactic bulge observed with high cadence. In 27 per cent of RRc
stars, we find additional non-radial mode, with characteristic period
ratio, Px/P1O{include.in}(0.6, 0.64). It strongly corroborates
the conclusion arising from the analysis of space photometry of RRc
stars, that this form of pulsation must be common. In the Petersen
diagram the stars form three sequences. In 20 stars, we find two or
three close secondary modes simultaneously. The additional modes are
clearly non-stationary. Their amplitude and/or phase vary in time. As
a result, the patterns observed in the frequency spectra of these
stars may be very complex. In some stars, the additional modes split
into doublets, triplets or appear as a more complex bands of increased
power. Subharmonics of additional modes are detected in 20 per cent of
stars. They also display a complex structure. Including our previous
study of the OGLE-III Galactic bulge data, we have discovered 260 RRc
and 2 RRd stars with the additional non-radial mode, which is the
largest sample of these stars so far. The additional mode is also
detected in two Blazhko RRc stars, which shows that the modulation and
additional non-radial mode are not exclusive.
Description:
In the analysis, we used data from the fourth phase of the OGLE
project (Soszynski et al., 2014, Cat. J/AcA/64/177; Udalski et al.
2015AcA....65....1U 2015AcA....65....1U).
OGLE-IV collection of variable stars contains 38257 RR Lyrae stars
from the Galactic bulge, including 10825 RRc stars and 174 RRd
stars. For the analysis, we selected stars pulsating in the first
overtone (RRc and RRd) placed in the most frequently observed fields
(501 and 505 in OGLE-IV).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 79 157 Properties of stars with non-radial mode (OGLE-IV)
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See also:
J/AcA/61/1 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2011)
J/AcA/64/177 : OGLE Galactic Bulge Fields RR Lyrae stars (Soszynski+, 2014)
J/ApJ/651/197 : Galactic Bulge OGLE fundamental-mode RR Lyr (Collinge+, 2006)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- --- [OGLE-BLG-RRLYR-]
16- 20 I5 --- Name OGLE-BLG-RRLYR- number
22- 28 F7.5 d P10 Period of the first overtone
30- 36 F7.5 d Px Period of additional mode
38- 44 F7.5 --- Px/P1O Px-to-P10 period ratio
46- 52 F7.5 mag A10 Amplitude of the first overtone
54- 60 F7.5 mag Ax Amplitude of additional mode
62- 68 F7.5 --- Ax/A1O Ax-to-A10 amplitude ratio
69- 79 A11 --- Rem Remarks (1)
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Note (1): Remarks as follows:
a = period change
bl = Blazhko effect
td = signal visible only after time-dependent pre-whitening
c = combination frequency
s = power excess at subharmonic
d = dublet
t = triplet
e = additional frequency
g = non-stationary fx
f = complex structure of fx
sr = half of the first season removed
h = stars detected in OGLE-III data (Netzel et al. 2015a).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Mar-2016