Long-period High-amplitude Red Variables in the KELT Survey

Abstract

We present a sample of 4,132 Mira-like variables (red variables with long periods and high amplitudes) in the Kilodegree Extremely Little Telescope (KELT) survey. Of these, 814 are new detections. We used 2MASS colors to identify candidate asymptotic giant branch (AGB) stars. We tested for photometric variability among the sample and used Lomb-Scargle to determine the periodicity of the variable sample. We selected variables with high amplitudes and strong periodic behavior using a Random Forest classifier.Of the sample of 4,132 Mira-like variables, we estimate that 70% are Miras, and 30% are semi-regular (SR) variables. We also adopt the method of using (W RP − W Ks ) vs.

An infrared study of Galactic OH/IR stars. III. Variability properties of the Arecibo sample

“…These observations taken in 2000-2005 give an irregular behaviour of the light curve with peak-to-peak amplitudes < ∼ 1 mag. A periodic light curve with P = 1019 days and an amplitude of ∆R KELT ∼ 1 mag was observed in the KELT Survey (Arnold et al 2020). Its optical (ASAS-SN and Gaia) light curve shows a peculiar shape with a periodicity compatible with the period obtained from the KELT survey.…”

“…The third and last quality check was done by comparing our results with light curves and period estimations publicly available for part of the Arecibo sample. We did an extensive search among the optical public surveys ASAS-SN, ATLAS (Heinze et al 2018), Catalina (Drake et al 2014), Gaia DR2, and KELT (Arnold et al 2020), in the General Catalogue of Variable Stars GCVS (Samus' et al 2017), and in the literature (Carter et al 1992;Herman & Habing 1985;Le Bertre 1993;Tang et al 2008;Urago et al 2020;Usatov & Nosulchik 2008;Vogt et al 2016;Whitelock et al 1994), obtaining periods for 193 (∼ 50%) objects in our sample.…”

The OGLE Collection of Variable Stars: Nearly 66,000 Mira Stars in the Milky Way

“…The growing number of known Miras-and therefore the ability to use them to study the structures of galaxies and population properties-has been possible thanks to large-scale surveys providing multiband time-series photometry or spectroscopy of variable stars. Among the various sky surveys, one can distinguish, e.g., the Asteroid Terrestrial-impact Last Alert System (Heinze et al 2018), the All Sky Automated Survey (ASAS; Pojmański 1997), the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al 2014;Jayasinghe et al 2019), the Catalina Sky Survey (Drake et al 2014, 2017), Gaia (Gaia Collaboration et al 2016, 2018Mowlavi et al 2018), the Kilodegree Extremely Little Telescope (Pepper et al 2007;Arnold et al 2020), the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (Yao et al 2017), the MAssive Compact Halo Objects (Alcock et al 1995;Bernhard & Hümmerich 2013), the Panoramic Survey Telescope and Rapid Response System (Chambers et al 2016;Flewelling et al 2020), the VISTA Variables in the Via Lactea (Minniti et al 2010), the Zwicky Transient Facility (ZTF; Bellm et al 2019;Chen et al 2020), and, finally, the Optical Gravitational Lensing Experiment (OGLE; Soszyński et al 2013;Udalski et al 2015).…”

MOA-2019-BLG-008Lb: A New Microlensing Detection of an Object at the Planet/Brown Dwarf Boundary

“…As described later in this work, we determined that the source star is a red giant. Many red giants exhibit variability at the ∼10% level (Wray et al 2004;Wyrzykowski et al 2006;Percy et al 2008;Soszyński et al 2013;Arnold et al 2020), and it is possible that this is also the case for this source, despite the apparently very long period P 1000 days. Because this trend manifests over very long timescales (several years), much longer than the duration of the actual microlensing event (weeks), it does not have any noticeable effect on the determination of the parameters of this event, which are primarily derived from the detailed morphology of the microlensing light curve.…”