Are all RR Lyrae stars modulated?

Kovács, G.

doi:10.1051/0004-6361/201833181

Cited by 20 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in agreement with the landmark results of the Konkoly Blazkho Survey that found it to be 47% (of 30 stars) and 43% (of 105 stars) for short-and long-period RRab stars (Jurcsik et al 2008;Sódor 2012). In contrast to these findings, Kovács (2018) found the signs of modulation, in the form of frequency side peaks, in 91% of 151 RR Lyrae stars in the C1-C4 Campaigns of K2 mission. A subset of the targets overlap with our sample in C3-C4.…”

Section: Occurrence Of Amplitude and Phase Changessupporting

confidence: 91%

Extended Aperture Photometry of K2 RR Lyrae stars

et al. 2017

View full text Add to dashboard Cite

Abstract. We present the method of the Extended Aperture Photometry (EAP) that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC) pipeline applied on the automated Single Aperture Photometry (SAP) and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP) data. The need for custom photometric pipelinesK2 observations suffer from various instrumental effects. The most serious one is the variation in spacecraft attitude that is corrected on a 6-hour timescale. Various methods have been developed to tackle these issues but neither is really optimal for RR Lyrae stars. Main characteristics of RR Lyrae photometry are the ∼6-12 hour periods (in the range of the correction frequency) and sharp features in the light curve (false positives for outliers). Also, we are interested in the full-amplitude variation, and not in a detrended (systematics-corrected) light curve that other pipelines offer. The KepSFF pipeline [5], for example, is confused by the pulsation, and detrended light curves are of lower quality than the raw fluxes, in several cases. The K2SC pipeline [1] removes the position-dependent systematics from the SAP and PDCSAP light curves. PDCSAP data are already free from systematic trends removed by the PDC (Pre-search Data Conditioning) method [4].Here we compare our solution for RR Lyrae stars with the outputs of K2SC pipeline. In many cases, EAP photometry retains the full amplitude much better than SAP/PDCSAP-based light curves, but it is sensitive to contamination from blended sources. A simple way: Extended Aperture Photometry (EAP)We created new apertures for every star. The apertures were defined to contain the movements of the stars within the target pixel masks, but to avoid contamination from nearby stars whenever possible. Although this method produces a very slightly increased noise from the background pixels, in many cases it also preserves the pulsation e-mail: eplachy@konkoly.hu amplitudes throughout the campaign much better than the SAP and PDCSAP fluxes. After the photometry, we removed all points with SAP_QUALITY flags larger than 0, except for C2, where we also kept the large number of points with flags value of 2 15 (16384).We then ran an automated Fourier analysis script on the light curves to construct an initial fit for sigma clipping [2]. The fit was subtracted from the data, all >3 sigma outliers from the residuals were removed, then the fit was added back. Figure 1 displays four examples of RR Lyrae stars from Campaign 4. Examples EPIC 210438688 (K p = 17.387 mag)The aperture used by the Kepler pipeline is clearly undersized. The SAP data indicates that the PSF periodically moved out of the SAP aperture during the second half of the campaign, leading to significant flux l...

show abstract

Section: Occurrence Of Amplitude and Phase Changessupporting

confidence: 91%

Extended Aperture Photometry of K2 RR Lyrae stars

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Various studies show that about 40-50 per cent of classical RR Lyrae stars (hereafter RRLs) pulsating in the fundametal mode show the quasi-periodic variations in amplitude and phase of light curves (see Kovacs 2016). Kovacs (2018) even proposes based on K2 data that up to 100 per cent of RRLs has the Blazhko effect, which is, however, in contrast to results by Plachy et al (2019) who used the method of extended aperture photometry and detected only 45 per cent of stars to be modulated. This light curve modulation, which is usually called the Blazhko effect (Blažko 1907), lacks the explanation even a century after its discovery.…”

Section: Introductionmentioning

confidence: 71%

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

Skarka

Prudil

Jurcsik

2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

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 days. 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. Double modulation was found in 25 per cent of the studied stars. Only 6.3 per cent of modulated stars belongs to the Oosterhoff group II.

show abstract

“…For high-precision photometric time series analysis, application of filtering methods that clean up the data from colored noise play a crucial role in the full utilization of the signal content of the time series (i.e., see Kovacs et al 2005, Tamuz et al 2005, Bakos et al 2010, Smith et al 2012. Our decision to stay with the more standard photometric data stems from the following reasons: i) Not all datasets contain these filtered LCs (e.g., ASAS-SN); ii) Since the amplitude of the light variation is large compared to that of the colored noise, the application of these filtering methods should consider this fact, otherwise the filtered signals will be distorted (see Kovacs 2018). The systematics-filtered LCs, available at the download sites do not have a proper correction for this effect; iii) Tests made with systematics-filtered LCs as given at the download sites (i.e., not containing the signal reconstruction feature 1 https://hatnet.org/ 2 The photometric time series from the HatNet project is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) (Wright et al 2010) through the ASAS-SN supernova search program (Shappee et al 2014 andKochanek et al 2017) to the inventory of AAVSO.…”

Section: Datasets Derived O-c Valuesmentioning

confidence: 99%

The hierarchical triple nature of the former red nova precursor candidate KIC 9832227

Kovács

Hartman

Bakos

2019

A&A

Self Cite

View full text Add to dashboard Cite

We revisit the issue of period variation of the recently claimed red nova precursor candidate KIC 9832227. By using the data gathered during the main mission of the Kepler satellite, those collected by ground-based wide-field surveys and other monitoring programs (such as ASAS-SN), we find that the currently available timing data strongly support a model consisting of the known W UMa binary and a distant low-mass companion with an orbital period of ∼ 13.5 years. The period of the W UMa component exhibits a linear period decrease with a pace of (1.10 ± 0.05) × 10 −6 days per year, within the range of many other similar systems. This rate of decrease is several orders of magnitude lower than that of V1309 Sco, the first (and so far the only) well-established binary precursor of a nova observed a few years before the outburst. The high-fidelity fit of the timing data and the conformity of the derived minimum mass of (0.38 ± 0.02) M ⊙ of the outer companion from these data with the limit posed by the spectroscopic non-detection of this component, are in agreement with the suggested hierarchical nature of this system.

show abstract

Are all RR Lyrae stars modulated?

Cited by 20 publications

References 21 publications

Extended Aperture Photometry of K2 RR Lyrae stars

Extended Aperture Photometry of K2 RR Lyrae stars

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

The hierarchical triple nature of the former red nova precursor candidate KIC 9832227

Contact Info

Product

Resources

About