Asteroseismology of RR Lyrae stars with non-radial modes

Netzel, H.; Smolec, R.

doi:10.48550/arxiv.2206.12853

Cited by 1 publication

(3 citation statements)

References 46 publications

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“…Both plots indicate that the blue edge of the instability strip is populated by pure overtone pulsators, but cooler RRc stars almost always feature at least one type of extra mode. This is in good agreement with previous observations (Jurcsik et al 2015;Smolec et al 2017;Molnár et al 2022) and with the linear model calculations of Netzel & Smolec (2022). The agreement between the distribution of the observed f 0.61 modes and the linearly excited high-modes supports the hypothesis of Dziembowski (2016) that we are indeed observing high radial-order modes in overtone pulsators.…”

Section: Color-magnitude Diagramsupporting

confidence: 92%

“…11. For reference, we also plotted RR 0.68 stars detected in the OGLE data (Netzel et al 2015). The stars studied here are centred on a period ratio of around 0.685, which is slightly lower than what was observed for the OGLE sample, where the average period ratio was around 0.686.…”

Section: Rr 068 Starsmentioning

confidence: 79%

“…Another group of multi-mode RR Lyrae stars are the socalled RR 0.68 stars (Netzel et al 2015). In these stars, the dominant pulsation mode is the first overtone.…”

Section: Introductionmentioning

confidence: 99%

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Frequency analysis of the first-overtone RR Lyrae stars based on the Extended Aperture Photometry from the K2 data

Netzel¹,

Molnar²,

Plachy³

et al. 2023

Preprint

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Context. Additional low-amplitude signals are observed in many RR Lyrae stars, beside the pulsations in radial modes. The most common ones are short-period signals forming a period ratio of around 0.60-0.65 with the first overtone, or long-period signals forming a period ratio of around 0.68. The RR Lyrae stars may also exhibit quasi-periodic modulation of the light curves, known as the Blazhko effect. Aims. We used the extensive sample of the first-overtone RR Lyrae stars observed by the Kepler telescope during the K2 mission to search for and characterize these low-amplitude additional signals. K2 data provides space-based photometry for a statistically significant sample. Hence this data is excellent to study in detail pulsation properties of RR Lyrae stars. Methods. We used K2 space-based photometry for RR Lyrae candidates from Campaigns 0-19. We selected RR Lyrae stars pulsating in the first overtone and performed a frequency analysis for each star to characterize their frequency contents. Results. We classified 452 stars as first-overtone RR Lyrae. From that sample, we selected 281 RR 0.61 stars, 67 RR 0.68 stars, and 68 Blazhko stars. We found particularly interesting stars which show all of the above phenomena simultaneously. We detected signals in RR 0.61 stars that form period ratios lower than observed for the majority of stars. These signals likely form a new sequence in the Petersen diagram, around a period ratio of 0.60. In 32 stars we detected additional signals that form a period ratio close to that expected in RRd stars, but the classification of these stars as RRd is uncertain. We also report a discovery of additional signals in eight stars that form a new group in the Petersen diagram around the period ratio of 0.465-0.490. The nature of this periodicity remains unknown.

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