Fourier Decomposition of RR Lyrae light curves and the SX Phe population in the central region of NGC 3201

Abstract

distancia. De esta manera hemos obtenido, para la metalicidad, el valor medio [Fe/H] ZW = −1.483 ± 0.006 (estadístico) ±0.090 (sistemático), y para la distancia, 5.000 ± 0.001 kpc (estadístico) ±0.220 (sistemático). La metalicidad y la distancia estimados a partir de dos estrellas RRc son consistentes con los anteriores. Debido a la presencia de enrojecimiento diferencial, derivamos valores individuales de E(B − V ) para las estrellas RR Lyrae analizando sus curvas de color V −I. El valor promedio encontrado es E(B −V ) = 0.23±0.02. Una exploración de las curvas de luz de las estrellas en la región de las blue stragglers condujo al descubrimiento de tres nuevas variables SX Phe. La relación periodo-luminosidad de las estrellas SX Phe se empleó para obtener una determinación independiente de la distancia al cúmulo y de los enrojecimientos individuales. La distancia calculada fue de 5.0 kpc.

Variability in NGC 3201 Giant Stars

“…Because of its period (P V = 0.36028 and P I = 0.35629), amplitude (A(V ) = 0.70348 and A (I) = 0.44557), and the shape of the phased LC, we suggest it to be a RR Lyrae ab-type star with a Blazhko effect (Blažko 1907). This star is located in the region of the HB, in the middle of the sample of RR Lyrae variable stars reported by Arellano Ferro et al (2014). This star does not present previous studies on its variability, which might have been due to its low amplitude.…”

“…The giant stars were selected by means of the magnitude color diagram. The data, provided by J. Ahumada and originally published by Arellano Ferro et al (2014), were obtained on 2013 March 20-23 at the Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina, using the 2.15 m telescope, and consist of V and I observations. The detector used was a Roper Scientific backilluminated CCD of 2048 × 2048 pixels with a 0 15 pix −1 scale and a field of view of approximately 5.1 × 5.1 arcmin 2 .…”

“…The details regarding data reduction and transformation to the VI standard magnitude system are described in Sections 2.2 and 2.3 of Arellano Ferro et al (2014). We will summarize the data reduction process, which was made with the DanDIA 6 pipeline (Bramich et al 2013).…”

“…9 (J2000) (Harris 1996(Harris , 2010 at a distance of ∼4.9 kpc. This GC has been the object of several studies, such as the debate about the presence of an intrinsic iron spread (e.g., Gonzalez & Wallerstein 1998;Muñoz et al 2013;Simmerer et al 2013;Mucciarelli et al 2015, and references therein) based on highresolution spectra from instruments such as the UVES-FLA-MES@VLT and MIKE@Magellan, as well as works regarding its variable star population (e.g., Layden & Sarajedini 2003;Arellano Ferro et al 2014;Kaluzny et al 2016). In fact, this GC is known for its rich content in variable stars, with a list of 121 targets according to the 2012 update of the Catalogue of Variable Stars in Globular Clusters (CVSGC; Clement et al 2001), containing RR Lyrae, SX Phoenicis, eclipsing binaries, and so on.…”

Variability in Early Post-main-sequence Stars in Globular Cluster NGC 3201

“…Furthermore, NGC 3201 is also known for its rich variable star population, having 121 targets according to the 2012 update of the Catalogue of Variable Stars in Globular Clusters (Clement et al 2001), as well as containing several RGB stars with lowamplitude light variations (Layden & Sarajedini 2003). Many works have been published in order to study its variables (e.g., Layden & Sarajedini 2003;Arellano Ferro et al 2014;Kaluzny et al 2016;Llancaqueo Albornoz et al 2021). As a further note on the topic of low-amplitude variable stars, there is knowledge about stars that display not only such low amplitudes but also large periods, being known as pulsating red giants, the classification having been provided by Olin Eggen in a series of papers (e.g., Eggen 1973Eggen , 1977.…”