J/A+A/635/A66 Humps and bumps in RR Lyrae stars (Prudil+, 2020)
Humps and bumps: the effects of shocks on the optical light curves of
fundamental-mode RR Lyrae stars.
Prudil Z., Dekany I., Smolec R., Catelan M., Grebel E.K., Kunder A.
<Astron. Astrophys. 635, A66 (2020)>
=2020A&A...635A..66P 2020A&A...635A..66P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry ; Milky Way
Keywords: stars: variables: RR Lyrae - techniques: photometric - shock waves -
Galaxy: bulge
Abstract:
We present the most extended and homogeneous study carried out so far
of the main and early shocks in 1485 RR Lyrae stars in the Galactic
bulge observed by the Optical Gravitational Lensing Experiment (OGLE).
We selected nonmodulated fundamental-mode RR Lyrae stars with
good-quality photometry. Using a self- developed method, we determined
the centers and strengths of main and early shock features in the
phased light curves. We found that the positions of both humps and
bumps are highly correlated with the pulsation properties of the
studied variables. Pulsators with a pronounced main shock are
concentrated in the low-amplitude regime of the period-amplitude
diagram, while stars with a strong early shock have average and
above-average pulsation amplitudes. A connection between the main and
early shocks and the Fourier coefficients is also observed. In the
color-magnitude diagram (CMD), we see a separation between stars with
strong and weak shocks. Variables with a pronounced main shock cluster
close to the fundamental red edge of the instability strip (IS), while
stars with a strong early shock tend to clump in the center and near
the fundamental blue edge of the IS. The appearance of shocks and
their properties appear to be independent of the direction of
evolution estimated from the period change rate of the studied stars.
In addition, the differences in the period change rate between the two
main Oosterhoff groups found in the Galactic bulge suggest that stars
of Oosterhoff type I are located close to the zero-age horizontal
branch while Oosterhoff type II variables are on their way toward the
fundamental red edge of the instability strip, and have therefore
already left the zero-age horizontal branch.
Description:
We provide the most extensive study of the effects of the main and
early shock on the light curves of RR Lyrae stars. We used photometric
data from the fourth data release of the OGLE Galactic bulge survey
for fundamental mode RR Lyrae variables. We selected only nonmodulated
variables with abundant and good-quality photometry studied in Prudil
et al. (2019MNRAS.484.4833P 2019MNRAS.484.4833P). In the end, we analyzed 1485 RR Lyrae
stars and estimated the location and size of the humps and bumps in
the phased light curves.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 141 1485 The photometric and shock properties of RR Lyraes
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See also:
J/AcA/64/177 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2014)
J/AcA/67/297 : OGLE Galactic center Cepheids and RR Lyrae (Soszynski+, 2017)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID OGLE-BLG-RRLYR-ID identifier,
OGLE BLG-RRLYR-NNNNN in Simbad
7- 12 F6.3 mag Kmag K band magnitude
14- 18 F5.3 mag AmpK K band amplitude
20- 25 F6.3 --- [Fe/H] Photometric metallicity
27- 31 F5.3 --- e_[Fe/H] Error on Photometric metallicity
33- 37 F5.3 mag VMAG Absolute magnitude in V
39- 43 F5.3 mag e_VMAG Error on absolute magnitude in V
45- 50 F6.3 mag IMAG Absolute magnitude in I
52- 56 F5.3 mag e_IMAG Error on absolute magnitude in I
58- 63 F6.3 mag KMAG Absolute magnitude in K
65- 69 F5.3 mag e_KMAG Error on absolute magnitude in K
71- 76 F6.3 --- humpx x-coordinate of the hump
78- 84 F7.4 --- humpy y-coordinate of the hump
86- 92 F7.4 --- bumpx x-coordinate of the bump
94- 99 F6.4 --- bumpy y-coordinate of the bump
101-106 F6.4 --- Amphump Amplitude of the hump
108-113 F6.4 --- Ampbump Amplitude of the bump
115 I1 --- OO [1/2] Oosterhoff group
117-127 E11.4 --- a2 Parameter for calculation of the period change
129-137 E9.4 --- e_a2 Error parameter for calculation of the
period change
139 I1 --- Classhump [1/4] Visual classification of the hump (1)
141 I1 --- Classbump [1/4] Visual classification of the bump (1)
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Note (1): We visually classified all RR Lyrae phase-folded light curves into
four categories (numbered 1 - 4) based on the visual prominence of the
aforementioned phase curve features (with '4' signifying a strong and
'1' a weak shock effect on the phased light curve).
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Acknowledgements:
Zdenek Prudil, prudilz(at)ari.uni-heidelberg.de
(End) Zdenek Prudil [ARI, Germany], Patricia Vannier [CDS] 05-Feb-2020