Long period variables in the Large Magellanic Cloud from the EROS-2 survey

Abstract

Context. The EROS-2 survey has produced a database of millions of time series from stars monitored for more than six years, allowing us to classify some of their sources into different variable star types. Among the so-called, long period variables (LPVs), which are known to follow particular sequences in the period-luminosity diagram, we find long secondary period variables whose variability origin remains a matter of debate. Aims. We analyze data for the 856 864 variable stars that have been discovered in the Large Magellanic Cloud (LMC) that are present in the EROS-2 database, to detect, classify, and characterize LPVs. Methods. Our method for identifying LPVs is based on the statistical Abbe test. It investigates the regularity of the light curve with respect to the survey duration in order to extract candidates with long-term variability. The period search is performed using Deeming, Lomb-Scargle, and generalized Lomb-Scargle methods, combined with a Fourier series fit. Color−magnitude, period-magnitude, and period-amplitude diagrams are used to characterize our candidates.Results. We present a catalog of 43 551 LPV candidates for the Large Magellanic Cloud. For each of them, we provide up to five periods, a mean magnitude in EROS-2, 2MASS, and Spitzer bands, B E −R E color, R E amplitude, and spectral type. We use infrared data to distinguish between RGB, O-rich, C-rich, and extreme AGB stars. Properties of our LPV candidates are investigated by analyzing period-luminosity and period-amplitude diagrams.

Luminosities and mass-loss rates of Local Group AGB stars and red supergiants

“…For all stars additional broadband photometry ranging from the optical to the mid-IR was collected from the literature, primarily using VizieR 5 and the NASA/IPAC Infrared Science Archive 6 , using the coordinates given in Tables A.1 and A.2. In the optical we collected U BVI data from Zaritsky et al (2002Zaritsky et al ( , 2004 for the LMC and SMC, U BVR data from Massey (2002) for the MCs, BVRI data from Oestreicher et al (1997) for RSGs in the LMC, OGLE-iii VI mean magnitudes from Udalski et al (2008a,b), EROS BR mean magnitudes from Kim et al (2014) and Spano et al (2011), MACHO BR mean magnitudes from Fraser et al (2008), and VRI data from Wood, Bessell & Fox (1983, hereafter WBF).…”

A dearth of OH/IR stars in the Small Magellanic Cloud

“…The second source, 2MASS J05241334−6829587, has a 24 µm flux density of 2.58, a J − K colour of 3.2 mag, a pulsation period of 899 days (Spano et al 2011). Within our SMC fields, there are three target sources that lie within the scaled LMC masing zone in the CMD: IRAS 00483−7347, IRAS 01074−7140, and MSX SMC 018 (Fig.…”

The EPOCH Project

“…Light curves obtained using the B E band generally have better photometric accuracy and also have more measurements than R E -band light curves (Spano et al 2011). Figure 1 shows a histogram of the B E band magnitude of about 550k sources in the EROS-2 LMC fields.…”

“…Beaulieu et al (2001) discovered two variable stars resembling Herbig Ae/Be or classical Be stars, Tisserand et al (2004) detected five R Coronae Borealis stars, Marquette et al (2009) discovered 185 new beat Cepheid variables, Spano et al (2011) reported forty-three thousand longperiod variable candidates, and Dubath et al (2012) found about 300 variable candidates from a subset of EROS-2 database but without identifying their variable types. Although these works produced some variable star candidates of various types, no study has searched the entire EROS-2 light curve database to classify different types of variable stars including δ Scuti stars, RR Lyraes, Cepheids, eclipsing binaries, and long-period variables.…”