scholarly journals Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – II. Modulation shapes, amplitudes, and periods

2020 ◽  
Vol 494 (1) ◽  
pp. 1237-1249
Author(s):  
M Skarka ◽  
Z Prudil ◽  
J Jurcsik
Keyword(s):  
Gravitational Lensing ◽  
Fundamental Mode ◽  
Pulsation Period ◽  
Galactic Bulge ◽  
Rr Lyrae Stars ◽  
Modulation Period ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
Two Parameters ◽  
Lyrae Stars

ABSTRACT The number of stars observed by the Optical Gravitational Lensing Experiment (OGLE) project in the Galactic bulge offers an invaluable chance to study RR Lyrae stars in a statistical manner. We used data of 3141 fundamental-mode RR Lyrae stars showing the Blazhko effect observed in OGLE-IV to investigate a possible connection between modulation amplitudes and periods, light curve, and pulsation characteristics. We found that there is no simple monotonic correlation between any combination of two parameters concerning the Blazhko and pulsation amplitudes, periods, and the shape of the light curves. There are only systematic limits. There is a bottom limit of the modulation period with respect to the pulsation period. We also found that the possible range of modulation amplitudes decreases with increasing pulsation period, which could point towards that the Blazhko effect is suppressed in cooler, larger, more luminous, and less metal abundant bulge RR Lyrae stars. Our investigation revealed that the distribution of the modulation periods can be described with two populations of stars with the mean modulation periods of 48 and 186  d. There is a certain region with a low density of the modulated stars, which we call the Blazhko valley, in the pulsation period–modulation period plane. Based on the similarity of the modulation envelopes, basically every star can be assigned to one of six morphological classes. The double modulation was found in 25 per cent of the studied stars. Only 6.3 per cent of modulated stars belong to the Oosterhoff group II.

scholarly journals RR Lyrae stars: New discoveries in the OGLE data

2015 ◽  
Vol 11 (A29B) ◽  
Author(s):  
Radoslaw Smolec ◽  
Henryka Netzel ◽  
Igor Soszyński
Keyword(s):  
Gravitational Lensing ◽  
Fundamental Mode ◽  
New Members ◽  
Rr Lyrae Stars ◽  
Period Ratio ◽  
Pulsation Mode ◽  
Rr Lyrae ◽  
Depth Analysis ◽  
Blazhko Effect ◽  
First Time

AbstractWe report our recent analyses of the RR Lyrae Optical Gravitational Lensing Experiment (OGLE) photometry, which resulted in several new discoveries and important results. We present the in-depth analysis of the Blazhko effect discovered in several double-mode RR Lyr (RRd) stars for the first time. Typically, these stars show multiple modulation periods and somewhat atypical first overtone to fundamental mode period ratio. Our analysis of the Galactic bulge stars allowed a significant (~factor of 10) increase of the members of the recently detected group of double-mode radial-non-radial RR Lyr stars, pulsating in the first overtone and in an yet unidentified shorter period mode, with characteristic period ratio of the two modes around 0.61. With more than 200 new members of the group first statistical analysis of the group properties is possible. Finally, we report the discovery of an even more intriguing group of double-periodic RR Lyr stars. The dominant pulsation mode in these stars corresponds to the radial first overtone. The additional period is longer, the period ratios (first overtone to a period of an yet unidentified origin) tightly cluster around 0.686. Hence the additional period is longer than the unseen fundamental mode and cannot correspond to a purely acoustic pulsation mode.

scholarly journals Kepler RR Lyrae stars: beyond period doubling

2013 ◽  
Vol 9 (S301) ◽  
pp. 459-460
Author(s):  
L. Molnár ◽  
J. M. Benkő ◽  
R. Szabó ◽  
Z. Kolláth
Keyword(s):  
Fundamental Mode ◽  
Period Doubling ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
Lyrae Stars

AbstractWe examined the complete short cadence sample of fundamental-mode Kepler RR Lyrae stars to further investigate the recently discovered dynamical effects such as period doubling and additional modes. Here we present the findings on four stars. V450 Lyr may be a non-classical double-mode RR Lyrae star pulsating in the fundamental mode and the second overtone. For the three remaining stars we observe the interaction of three different modes. Since the period ratios are close to resonant values, we observe quasi-repetitive patterns in the pulsation cycles in the stars. These findings support the mode-resonance explanations of the Blazhko effect.

scholarly journals The census of non-radial pulsation in first-overtone RR Lyrae stars of the OGLE Galactic bulge collection

2019 ◽  
Vol 487 (4) ◽  
pp. 5584-5592 ◽  
Author(s):  
H Netzel ◽  
R Smolec
Keyword(s):  
Gravitational Lensing ◽  
Incidence Rates ◽  
Statistical Properties ◽  
Radial Pulsation ◽  
Galactic Bulge ◽  
Frequency Spectra ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Low Amplitude ◽  
Lyrae Stars

ABSTRACT We analysed photometry for the up-to-date collection of the first-overtone RR Lyrae stars (RRc; 11 415 stars) and double-mode RR Lyrae stars (RRd; 148 stars) towards the Galactic bulge from the Optical Gravitational Lensing Experiment (OGLE). We analysed frequency spectra of these stars in search for additional, low-amplitude signals, beyond the radial modes. We focused on stars from two groups: RR0.61 and RR0.68. In the first group, additional low-amplitude signals have periods shorter than the first-overtone period; period ratios fall in the 0.60–0.64 range. In the second group, additional low-amplitude signals have periods longer than the first-overtone period; period ratios tightly cluster around 0.68. Altogether we have detected 960 and 147 RR Lyrae stars that belong to RR0.61 and RR0.68 groups, respectively, which yield the incidence rates of 8.3 and 1.3 per cent of the considered sample. We discuss statistical properties of RR Lyrae stars with additional periodicities. For RR0.61 group we provide strong arguments that additional periodicities are connected to non-radial pulsation modes of degrees ℓ = 8 and ℓ = 9, as proposed by Dziembowski. We have also detected two double-periodic variables, with two close periodicities, similar to RR Lyrae variable V37 in NGC 6362. Properties of these peculiar variables, which may form a new group of double-mode pulsators, are discussed.

scholarly journals Gaia Data Release 2

2019 ◽  
Vol 622 ◽  
pp. A60 ◽  
Author(s):  
G. Clementini ◽  
V. Ripepi ◽  
R. Molinaro ◽  
A. Garofalo ◽  
T. Muraveva ◽  
...  
Keyword(s):  
Time Series ◽  
Fundamental Mode ◽  
Globular Clusters ◽  
Pulsation Period ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Classical Cepheids ◽  
Data Release ◽  
Lyrae Stars ◽  
Multi Band

Context. The Gaia second Data Release (DR2) presents a first mapping of full-sky RR Lyrae stars and Cepheids observed by the spacecraft during the initial 22 months of science operations. Aims. The Specific Objects Study (SOS) pipeline, developed to validate and fully characterise Cepheids and RR Lyrae stars (SOS Cep&RRL) observed by Gaia, has been presented in the documentation and papers accompanying the Gaia first Data Release. Here we describe how the SOS pipeline was modified to allow for processing the Gaia multi-band (G, GBP, and GRP) time-series photometry of all-sky candidate variables and produce specific results for confirmed RR Lyrae stars and Cepheids that are published in the DR2 catalogue. Methods. The SOS Cep&RRL processing uses tools such as the period–amplitude and the period–luminosity relations in the G band. For the analysis of the Gaia DR2 candidates we also used tools based on the GBP and GRP photometry, such as the period–Wesenheit relation in (G, GRP). Results. Multi-band time-series photometry and characterisation by the SOS Cep&RRL pipeline are published in Gaia DR2 for 150 359 such variables (9575 classified as Cepheids and 140 784 as RR Lyrae stars) distributed throughout the sky. The sample includes variables in 87 globular clusters and 14 dwarf galaxies (the Magellanic Clouds, 5 classical and 7 ultra-faint dwarfs). To the best of our knowledge, as of 25 April 2018, the variability of 50 570 of these sources (350 Cepheids and 50 220 RR Lyrae stars) has not been reported before in the literature, therefore they are likely new discoveries by Gaia. An estimate of the interstellar absorption is published for 54 272 fundamental-mode RR Lyrae stars from a relation based on the G-band amplitude and the pulsation period. Metallicities derived from the Fourier parameters of the light curves are also released for 64 932 RR Lyrae stars and 3738 fundamental-mode classical Cepheids with periods shorter than 6.3 days.

scholarly journals The MACHO Project Large Magellanic Cloud Variable Star Inventory. XI. Frequency Analysis of the Fundamental‐Mode RR Lyrae Stars

2003 ◽  
Vol 598 (1) ◽  
pp. 597-609 ◽  
Author(s):  
C. Alcock ◽  
D. R. Alves ◽  
A. Becker ◽  
D. Bennett ◽  
K. H. Cook ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Fundamental Mode ◽  
Variable Star ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals Detecting shock waves in non-fundamental mode RR Lyrae using large sample of spectra in SDSS and LAMOST

2020 ◽  
pp. 181-186
Author(s):  
Xiao-Wei Duan ◽  
Xiao-Dian Chen ◽  
Li-Cai Deng ◽  
Fan Yang ◽  
Chao Liu ◽  
...  
Keyword(s):  
Shock Waves ◽  
Fundamental Mode ◽  
Variable Stars ◽  
Ionization Zone ◽  
Rr Lyrae Stars ◽  
Hydrogen Emission ◽  
Emission Signal ◽  
Rr Lyrae ◽  
Hydrogen Emission Lines ◽  
Blazhko Effect

Steps toward the nature inside RR Lyrae variables can not only improve our understanding of variable stars but also innovate the precision when we use them as tracers to map the structure of the universe. In this work, we develop a hand-crafted one-dimensional pattern recognition pipeline to fetch out the "first apparitions", the most prominent observational characteristic of shock. We report the first detection of hydrogen emission lines in the first-overtone and multi-mode RR Lyrae variables. We find that there is an anti-correlation between the intensity and the radial velocity of the emission signal, which is possibly caused by opacity changing in the helium ionization zone. Moreover, we find one RRd star with hydrogen emission that possibly shows Blazhko-type modulations. According to our discoveries, with an enormous volume of upcoming data releases of variable stars and spectra, it may become possible to build up the bridge between shock waves and big problems like the Blazhko effect in non-fundamental mode RR Lyrae stars.

Sign in / Sign up

Export Citation Format

Share Document