Stellar Variability in the VVV survey

Catelan, M.; Minniti, D.; Lucas, P. W.; Dékány, I.; Saito, R. K.; Angeloni, R.; Alonso-García, J.; Hempel, M.; Hełminiak, K. G.; Jordán, Andrés; Ramos, R. Contreras; Navarrete, C.; Beamin, J. C.; Rojas, A. F.; Gran, F.; Lopes, C. E. Ferreira; Peña, C. Contreras; Kerins, E.; Huckvale, L.; Rejkuba, M.; Cohen, Roger E.; Mauro, F.; Borissova, J.; Amigo, P.; Eyheramendy, S.; Pichara, Karim; Espinoza, N.; Navarro, C.; Hajdu, G.; Espinoza, Diego Nicolás Calderón; Muro, G.; Andrews, H.; Motta, V.; Kurtev, R.; Emerson, J. P.; Bidin, C. Moni; Chené, A. N.

doi:10.48550/arxiv.1310.1996

Cited by 11 publications

(14 citation statements)

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“…We couldn't identify the type of variable, since it is difficult to classify variability type, due to the few features showed in Ks bands (Catelan et al 2013;Alonso-García et al 2015).…”

Section: Variabilitymentioning

confidence: 99%

Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Muñoz

Geisler

Villanova

et al. 2018

A&A

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Context. The Bulge Globular Clusters (GCs) are key tracers of this central ancient component of our Galaxy. It is essential to understand their formation and evolution to study that of the bulge, as well as their relationship with the other Galactic GC systems (halo and disk GCs). High resolution spectroscopy is a powerful tool for such studies, allowing us to obtain a detailed chemical characterization and kinematics of the clusters and to compare their chemical patterns with those of their halo and disk counterparts. Aims. Our main goals are to obtain detailed abundances for a sample of seven red giant members of NGC 6528 in order to characterize its chemical composition and study the relationship of this GC with the bulge, and with other bulge, halo and disk GCs. Moreover, we analyze this cluster's behavior associated with the Multiple Populations (MPs) phenomenon. Methods. We obtained the stellar parameters and chemical abundances of light elements (Na, Al), iron-peak elements (V, Cr, Mn, Fe, Co, Ni, Cu), α-elements (O, Mg, Si, Ca, Ti) and heavy elements (Zr, Ba, Eu) in seven red giant members of NGC 6528 using high resolution spectroscopy from FLAMES-UVES. Results. We obtained in six stars of our sample a mean iron content of [Fe/H]=-0.14±0.03 dex, in good agreement with other studies. We found no significant internal iron spread. We detected one candidate variable star, which was excluded from the mean in iron content, we derived a metallicity in this star of [Fe/H]=-0.55±0.04 dex. Moreover, we found no extended O-Na anticorrelation but instead only an intrinsic Na spread. In addition, NGC 6528 does not exhibit a Mg-Al anticorrelation, and no significant spread in either Mg or Al. The α and iron-peak elements show good agreement with the bulge field star trend. The heavy elements are slightly dominated by the r-process. The chemical analysis suggests an origin and evolution similar to that of typical old Bulge field stars. Finally, we find remarkable agreement in the chemical patterns of NGC 6528 and another bulge GC, NGC 6553, suggesting a similar origin and evolution.

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“…We couldn't identify the type of variable, since it is difficult to classify variability type, due to the few features showed in Ks bands (Catelan et al 2013;Alonso-García et al 2015).…”

Section: Variabilitymentioning

confidence: 99%

Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Muñoz

Geisler

Villanova

et al. 2018

A&A

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“…Active Galactic Nuclei (AGN) can show up as point sources in the search through the GPS catalogues, and these objects are also variable in the near-infrared (Enya et al 2002;Cioni et al 2013). Other known classes of infrared variable stars include symbiotic stars (Corradi et al 2008), Cataclysmic Variables/Novae (Saito et al 2013) and Classical Be stars (Dougherty & Taylor 1994) (see also Catelan et al 2013, for a discussion on classes of near-infrared variable stars).…”

Section: Introductionmentioning

confidence: 99%

Extreme infrared variables from UKIDSS – I. A concentration in star-forming regions

Peña¹,

Lucas²,

Froebrich³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present initial results of the first panoramic search for high-amplitude near-infrared variability in the Galactic Plane. We analyse the widely separated two-epoch K-band photometry in the 5th and 7th data releases of the UKIDSS Galactic Plane Survey. We find 45 stars with ∆K > 1 mag, including 2 previously known OH/IR stars and a Nova. Even though the mid-plane is not yet included in the dataset, we find the majority (66%) of our sample to be within known star forming regions (SFRs), with two large concentrations in the Serpens OB2 association (11 stars) and the Cygnus-X complex (12 stars). Sources in SFRs show spectral energy distributions (SEDs) that support classification as Young Stellar Objects (YSOs). This indicates that YSOs dominate the Galactic population of high amplitude infrared variable stars at low luminosities and therefore likely dominate the total high amplitude population. Spectroscopic follow up of the DR5 sample shows at least four stars with clear characteristics of eruptive pre-main-sequence variables, two of which are deeply embedded. Our results support the recent concept of eruptive variability comprising a continuum of outburst events with different timescales and luminosities, but triggered by a similar physical mechanism involving unsteady accretion. Also, we find what appears to be one of the most variable classical Be stars.

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“…Comparing with known eruptive variables classes, G286.2032+0.1740, characterized by a long-term large-amplitude rising light curve, resembles an FUor object in its temporal behavior. In principle, high-amplitude variability in the NIR can be produced by various physical phenomena, including evolved giant and supergiant stars like Mira variables, cataclysmic variables and active galactic nuclei (AGN), etc (see Catelan et al 2013, for a discussion). However, none of these possibilities is consistent with the characteristics of G286.2032+0.1740, including its faintness, NIR color and shape of the light curve.…”

Section: Discussionmentioning

confidence: 99%

Stellar Variability in a Forming Massive Star Cluster

Cheng,

Andersen,

Tan

2020

Preprint

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We present a near-infrared (NIR) variability analysis for an 6 × 6 region, which encompasses the massive protocluster G286.21+0.17. The total sample comprises more than 5000 objects, of which 562 show signs of a circumstellar disk based on their infrared colors. The data includes HST observations taken in two epochs separated by 3 years in the F110W and F160W bands. 363 objects (7% of the sample) exhibit NIR variability at a significant level (Stetson index > 1.7), and a higher variability fraction (14%) is found for the young stellar objects (YSOs) with disk excesses. We identified 4 high amplitude (> 0.6 mag) variables seen in both NIR bands. Follow up and archival observations of the most variable object in this survey (G286.2032+0.1740) reveal a rising light curve over 8 years from 2011 to 2019, with a K band brightening of 3.5 mag. Overall the temporal behavior of G286.2032+0.1740 resembles that of typical FU Ori objects, however its pre-burst luminosity indicates it has a very low mass (< 0.12 M ), making it an extreme case of an outburst event that is still ongoing.

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Stellar Variability in the VVV survey

Cited by 11 publications

References 0 publications

Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Extreme infrared variables from UKIDSS – I. A concentration in star-forming regions

Stellar Variability in a Forming Massive Star Cluster

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