scholarly journals Discovery of the Blazhko effect in V1065 Aql, CzeV980, FI Sge, and CzeV1242

2018 ◽  
Author(s):  
Skarka M. ◽  
Cagas P.
Keyword(s):  
Blazhko Effect

scholarly journals Physical Parameter Determination for the δ Scuti Star HD 200925

2000 ◽  
Vol 176 ◽  
pp. 467-468 ◽  
Author(s):  
J. H. Peña ◽  
M. Paparó ◽  
R. Peniche ◽  
M. Rodríguez ◽  
M. A. Hobart ◽  
...  
Keyword(s):  
Physical Parameter ◽  
Time Scale ◽  
Parameter Determination ◽  
Theoretical Ratio ◽  
Blazhko Effect ◽  
Metal Abundance ◽  
Scuti Star

HD 200925 is an unusual star: the period is stable on a time scale of many years, yet it shows variations which are either large and irregular, or small, suggesting a possible Blazhko effect (Poretti 1984; Joner & Johnson 1985); it has larger values of Teff and log g derived from uvbyβ than those of dwarf Cepheids of similar period; and it has a somewhat higher metal abundance, [Fe/H], than the Hyades. Furthermore, in conflict to what Joner and McNamara (1983) determined – that m1 index shows no variation with temperature – HD 200925 shows a definite variation, unlike that predicted in Crawford (1979). No explanation of this has yet been found. Johnson & Joner (1986) also derived an unusual and unexpected value of [Fe/H]. Finally, with respect to the pulsation periods of this star, Mantegazza & Poretti (1986) determined the existence of two periods: one definite, 0.26730 d and a possible second one of 0.2138 d which yield a ratio of P2/P1 = 0.800, the theoretical ratio expected between the first and the second overtones, found in other pulsating variables. All of these facts make HD 200925 an interesting star, motivating the present study.

scholarly journals The Blazhko Effect of the RR Lyrae Star FM Persei

2001 ◽  
Vol 113 (785) ◽  
pp. 835-838 ◽  
Author(s):  
Kevin M. Lee ◽  
Edward G. Schmidt
Keyword(s):  
Rr Lyrae ◽  
Blazhko Effect

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 First Detection of a Frequency Multiplet in the Line Profile Variations of RR Lyrae: Towards an Understanding of the Blazhko Effect

2000 ◽  
Vol 176 ◽  
pp. 286-290 ◽  
Author(s):  
K. Kolenberg ◽  
C. Aerts ◽  
M. Chadid ◽  
D. Gillet
Keyword(s):  
Line Profile ◽  
Theoretical Models ◽  
Theoretical Modelling ◽  
Line Profiles ◽  
Multiplet Structure ◽  
Complete Understanding ◽  
Period Analysis ◽  
Essential Step ◽  
Rr Lyrae ◽  
Blazhko Effect

AbstractWe provide the first detection of a frequency multiplet in the line profile variations of RR Lyrae. Performing a period analysis on 669 high resolution line profiles obtained with the spectrograph ELODIE at OHP, we clearly detect a multiplet structure, with a separation equal to the Blazhko frequency, around the main frequency and its harmonics. The triplet components are very prominent; additional observations are needed to decide about the existence of a quintuplet. The complete understanding of the origin of the Blazhko effect still needs further theoretical modelling and better observations. Our detection of the frequency multiplet in the line profile variations is a first essential step towards a decisive confrontation between the theoretical models and the observations.

scholarly journals Oblique Pulsator Model for the Blazhko Effect of RR Lyrae Stars

1995 ◽  
Vol 155 ◽  
pp. 42-43
Author(s):  
Hiromoto Shibahashi ◽  
Masao Takata
Keyword(s):  
Rotation Axis ◽  
Oscillation Mode ◽  
Stellar Rotation ◽  
Rr Lyrae Stars ◽  
Aspect Angle ◽  
Rr Lyrae ◽  
Quadrupole Component ◽  
Blazhko Effect ◽  
Apparent Variation ◽  
Lyrae Stars

AbstractBy assuming that the RR Lyrae stars have fairly strong dipole magnetic fields with the symmetry axis oblique to the rotation axis of the star, we show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, which is axisymmetric with respect to the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent variation is interpreted as the Blazhko effect in RR Lyrae stars.

scholarly journals Blazhko Effect and Magnetic Field in RR Lyrae

2000 ◽  
Vol 176 ◽  
pp. 318-319
Author(s):  
M. Chadid ◽  
D. Gillet ◽  
K. Kolenberg ◽  
C. Aerts
Keyword(s):  
Magnetic Field ◽  
Pulsation Frequency ◽  
Frequency Splitting ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
Magnetic Model ◽  
Observational Techniques ◽  
The Magnetic Field

AbstractThe recent detection of a frequency splitting around the pulsation frequency and its harmonics points towards the magnetic model to explain the Blazhko effect. Here we show that it is urgent to confirm with modern observational techniques the existence of the magnetic field in RR Lyrae.

scholarly journals CCD VI time-series of the extremely metal-poor globular cluster M92: revisiting its variable star population

2020 ◽  
Vol 494 (3) ◽  
pp. 3212-3226 ◽  
Author(s):  
M A Yepez ◽  
A Arellano Ferro ◽  
D Deras
Keyword(s):  
Time Series ◽  
Globular Cluster ◽  
Variable Star ◽  
Variable Stars ◽  
Frequency Spectra ◽  
Fourier Decomposition ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
New Variables ◽  
Gaia Dr2

ABSTRACT We present an analysis of VI CCD time-series photometry of the Oo II type globular cluster M92. The variable star population of the cluster is studied with the aim of revising their classifications, identifications, frequency spectra, and to select indicators of the parental cluster metallicity and distance. The Fourier decomposition of RR Lyrae light curves lead to the estimation of mean [Fe/H]spec = −2.20 ± 0.18 and distance of 8.3 ± 0.2 kpc. Four new variables are reported: one RRd (V40), a multimode SX Phe (V41), an SR (V42), and one RRc (F1) that is most likely not a cluster member. The AC nature of V7 is confirmed. The double mode nature of the RRc star V11 is not confirmed and its amplitude modulations are most likely due to the Blazhko effect. Two modes are found in the known RRc variable V13. It is argued that the variable V30, previously classified as RRab is, in fact, a BL Her-type star not belonging to the cluster. Using the Gaia-DR2 proper motions, we identified 5012 stars in the field of the cluster, which are very likely cluster members, and for which we possess photometry, enabling the production of a refined colour–magnitude diagram. This also allowed us to identify a few variable stars that do not belong to the cluster. The RR Lyrae pulsation modes on the HB are cleanly separated by the first overtone red edge, a common feature in all Oo II-type clusters.

scholarly journals Blazhko Effect in the RR Lyrae Variables as a Result of Double Mode Pulsation

1980 ◽  
Vol 58 ◽  
pp. 511-517
Author(s):  
K.J. Borkowski
Keyword(s):  
Frequency Analysis ◽  
Fundamental Mode ◽  
Nonlinear Superposition ◽  
Number Of Components ◽  
The Third ◽  
Rr Lyrae ◽  
Blazhko Effect

AbstractOn the basis of a frequency analysis of light variations of AR Her a double-mode pulsation is proposed as an explanation of the Blazhko effect. The analysis revealed a number of components, which can all be interpreted as a result of nonlinear superposition of the fundamental mode, and a mode with period P = 1/(2/P0 + 1/PB) ~ P0/2, where P0 = 0d.470 and Pb = 31d.55 denote the fundamental and the Blazhko effect periods, respectively.The P ⋍ P0/2 mode can be identified as the second or the third radial overtone. In both these cases the “beat” masses derived from a comparison of the calculated (nonadiabatic) and observed period ratios for RR Lyrae variables with Blazhko effect are different from their evolutionary masses.

scholarly journals The Blazhko Effect of the RR Lyrae Star DR Andromedae

2001 ◽  
Vol 113 (787) ◽  
pp. 1140-1144 ◽  
Author(s):  
Kevin M. Lee ◽  
Edward G. Schmidt
Keyword(s):  
Rr Lyrae ◽  
Blazhko Effect
Sign in / Sign up

Export Citation Format

Share Document