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.

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.

The K2 RR Lyrae Survey

2017 ◽  
Vol 14 (S339) ◽  
pp. 83-86
Author(s):  
R. Szabó
Keyword(s):  
Statistical Study ◽  
Period Doubling ◽  
Variable Stars ◽  
Galactic Structure ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Continuous Coverage ◽  
Blazhko Effect ◽  
Lyrae Stars

AbstractIn the framework of this project, the K2 RR Lyrae Survey, we proposed to observe thousands of RR Lyrae stars along the Ecliptic in Kepler’s K2 Mission. The high photometric precision and the 80-to-90-day continuous coverage enabled us to investigate in unprecedented detail the light variations of these variable stars which can trace galactic structure. The survey enabled us to conduct a thorough statistical study of RR Lyrae pulsation dynamics, including both old and more recently discovered dynamical phenomena such as resonances, non-radial modes, period doubling and the Blazhko effect. This talk described the K2 RR Lyrae Survey, and discussed the prospects of combining our endeavour with Gaia, LSST and other surveys in the context of studies of Galactic archeology.

scholarly journals Frequency Analysis of a Subset of Fundamental Mode RR Lyrae Stars from the MACHO Project Large Magellanic Cloud Database

2002 ◽  
Vol 185 ◽  
pp. 412-413
Author(s):  
D.L. Welch ◽  
G. Kovács ◽  
K.H. Cook ◽  
C. Alcock ◽  
R. Allsman ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Fundamental Mode ◽  
Power Spectra ◽  
Frequency Component ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
Two Peaks

AbstractWe present the preliminary results of a frequency analysis of 1457 fundamental mode RR Lyrae (RR0) stars in the Large Magellanic Cloud (LMC) from MACHO Project photometry. We find the same classes of pulsational behavior as were found in our earlier survey of first overtone RR Lyrae (RR1) stars. Variables whose prewhitened power spectra contain one or two peaks close to the main frequency component in the original power spectra are commonly known as Blazhko-type variables. The present analysis shows the overall frequency of Blazhko-type stars in the total RR0 population analysed to date to be ≈ 10%. This is lower than the often cited Galactic field/globular rate of 20-30% (Szeidl, 1988).The incidence rate of Blazhko-type variability in the LMC appears to be about three times higher in RR0 stars than in RR1 stars. This puts important constraints on possible models of the Blazhko effect.

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 Impact of Observing Strategy on the Reliable Classification of Standard Candle Stars: Detection of Amplitude, Period, and Phase Modulation (Blazhko Effect) of RR Lyrae Stars with LSST

2021 ◽  
Vol 258 (1) ◽  
pp. 4
Author(s):  
Nina Hernitschek ◽  
Keivan G. Stassun
Keyword(s):  
Phase Modulation ◽  
Variable Stars ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Standard Candle ◽  
Blazhko Effect ◽  
The Impact ◽  
Lyrae Stars

Abstract The Vera C. Rubin Observatory will carry out its Legacy Survey of Space and Time (LSST) with a single-exposure depth of r ∼ 24.7 and an anticipated baseline of 10 yr, allowing access to the Milky Way’s old halo not only deeper than, but also with a longer baseline and better cadence than, e.g., PS1 3π. This will make the LSST ideal to study populations of variable stars such as RR Lyrae stars (RRL). Here, we address the question of observing strategy optimization of LSST, as survey footprint definition, single-visit exposure time, as well as the cadence of repeat visits in different filters are yet to be finalized. We present metrics used to assess the impact of different observing strategies on the reliable detectability and classification of standard candle variable stars, including detection of amplitude, period, and phase modulation effects of RRL (the so-called Blazhko effect), by evaluating metrics for simulated potential survey designs. So far, due to the depths and cadences of typical all-sky surveys, it has been nearly impossible to study this effect on a larger sample. All-sky surveys with relatively few observations over a moderately long baseline allow only for fitting phase-folded RRL light curves, thus integrating over the complete survey length and hiding any information regarding possible period or phase modulation during the survey. On the other hand, surveys with cadences fit to detect slightly changing light curves usually have a relatively small footprint. LSST’s survey strategy, however, will allow for studying variable stars in a way that makes population studies possible.

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 Fundamental Mode and First Overtone Mode Cepheids in the Small Magellanic Cloud

1993 ◽  
Vol 139 ◽  
pp. 349-356
Author(s):  
H.A. Smith ◽  
N.A. Silbermann ◽  
S.R. Baird ◽  
J.A. Graham
Keyword(s):  
Frequency Distribution ◽  
Fundamental Mode ◽  
Surface Density ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Photographic Survey ◽  
Lyrae Stars

AbstractWe report results of a new photographic survey of variable stars in a 1 x 1.3 degree region near the Northeast Arm of the Small Magellanic Cloud. We have discovered 133 new variable stars in this field and have determined periods and B lightcurves for 78 new and 72 previously known variables. At periods shorter than about 3 days, the Cepheid period-luminosity relation splits into two sequences. The brighter sequence is believed to be populated by stars pulsating in the first overtone radial mode, wherecis the fainter sequence is populated by fundamental mode pulsators. The peak in the Cepheid period-frequency distribution occurs near a period of 1.8 days. The surface density of RR Lyrae stars in this field is comparable to that in an outlying SMC field near NGC 121.

scholarly journals Time-Domain Astrophysics with SuperWASP

2011 ◽  
Vol 7 (S285) ◽  
pp. 382-384
Author(s):  
A. J. Norton ◽  
Keyword(s):  
Binary Stars ◽  
Variable Stars ◽  
Eclipsing Binaries ◽  
Rr Lyrae Stars ◽  
Long Baseline ◽  
Rr Lyrae ◽  
Look Ahead ◽  
Blazhko Effect ◽  
Data Points ◽  
Lyrae Stars

AbstractSuperWASP is the world's leading ground-based survey for transiting exoplanets. Its database now contains over 300 billion data points covering 30 million unique objects from 10 million images obtained over 1700 nights since 2004. In addition to having discovered 70 transiting exoplanets, SuperWASP enables long-baseline, high-cadence studies of variable stars to be performed. We summarise some of the studies already carried out, and look ahead to the prospects for studying periodic variables with varying periods. The science which is thus supported will include studies of the Blazhko effect in RR Lyræ stars, migrating starspots in rotational variables, third bodies in eclipsing binaries, and coalescing binary stars.

scholarly journals General Properties of the Two Groups of Globular Clusters and Their Variable Stars

1975 ◽  
Vol 67 ◽  
pp. 541-543
Author(s):  
A. V. Mironov ◽  
N. N. Samus'
Keyword(s):  
Chemical Composition ◽  
Globular Clusters ◽  
Variable Stars ◽  
Rr Lyrae Stars ◽  
General Properties ◽  
Rr Lyrae ◽  
Lyrae Stars

The dependences of the numbers of variable stars in globular clusters on the chemical composition are studied. For given metallicity the numbers of RR Lyrae stars reduced to some definite total number of stars in the cluster are different for the two groups of globular clusters introduced by Mironov.

Sign in / Sign up

Export Citation Format

Share Document