Bulge RR Lyrae stars in the VVV tile b201

Gran, F.; Minniti, D.; Saito, R. K.; Navarrete, C.; Dékány, I.; McDonald, Iain; Ramos, R. Contreras; Catelan, M.

doi:10.1051/0004-6361/201424333

Cited by 23 publications

(27 citation statements)

References 38 publications

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“…Figure 2 shows the J −K s colour-magnitude diagram (CMD) for the complete RR Lyrae catalog with tile b201 as a comparison field. The RR Lyrae stars lie in a wide range of mean-K s magnitudes owing to their distance distribution in the Galaxy, but the J − K s colour is limited between ∼0.0 and 0.6, similar values to those reported by Gran et al (2015).…”

Section: Resultssupporting

confidence: 81%

“…We note that none of our classified RRab stars has tagged eclipsing binary counterparts in the GCVS, even though we do not discard minor contamination due to eclipsing binaries that can mimic RRab stars. Finally, 27 of the RRab stars in the tile b201 have already een reported y Gran et al (2015).…”

Section: Detection and Classification Of Rr Lyrae Starsmentioning

confidence: 92%

“…A similar analysis was presented in Carpenter et al (2001) to detect variable candidates. If this value exceeds the imposed cutoff of χ 2 = 2 (see Gran et al 2015), the time-series periodicities are tested by the analysis of variance (AoV) statistic (Schwarzenberg-Czerny 1989) in the RR Lyrae stars period range (0.2 ≤ P (days) ≤ 1.2). After this process the light curves were visually classified.…”

Section: Detection and Classification Of Rr Lyrae Starsmentioning

confidence: 99%

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Mapping the outer bulge with RRab stars from the VVV Survey

Gran

Minniti

Saito

et al. 2016

A&A

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Context. The VISTA Variables in the Vía Láctea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. In particular, enormous numbers of RR Lyrae stars have been discovered in the inner regions of the bulge (−8• ) by optical surveys such as OGLE and MACHO, but leaving an unexplored window of more than ∼47 sq deg (−10.0• and −10.3• b −8.0 • ) observed by the VVV Survey. Aims. Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to that of red clump stars, which is known to trace a X-shaped structure, in order to determine whether these two different stellar populations share the same Galactic distribution. Methods. A search for RR Lyrae stars was performed in more than ∼47 sq deg at low Galactic latitudes (−10.3• ). In the procedure the χ 2 value and analysis of variance (AoV) statistic methods were used to determine the variability and periodic features of the light curves, respectively. To prevent misclassifications, the analysis was performed only on the fundamental mode RR Lyrae stars (RRab) owing to similarities found in the near-IR light curve shapes of contact eclipsing binaries (W UMa) and first overtone RR Lyrae stars (RRc). On the other hand, the red clump stars of the same analyzed tiles were selected, and cuts in the color-magnitude diagram were applied and the maximum distance restricted to ∼20 kpc in order to construct a similar catalog in terms of distances and covered area compared to the RR Lyrae stars. Results. We report the detection of more than 1000 RR Lyrae ab-type stars in the VVV Survey located in the outskirts of the Galactic bulge. A few of them are possibly associated with the Sagittarius Dwarf Spheroidal Galaxy. We calculated colours, reddening, extinction, and distances of the detected RR Lyrae stars in order to determine the outer bulge 3D structure. Our main result is that, at the low galactic latitudes mapped here, the RR Lyrae stars trace a centrally concentrated spheroidal distribution. This is a noticeably different spatial distribution to the one traced by red clump stars known to follow a bar and X-shaped structure. We estimate the completeness of our sample at 80% for K s ≤ 15 mag.

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Section: Resultssupporting

confidence: 81%

Section: Detection and Classification Of Rr Lyrae Starsmentioning

confidence: 92%

Section: Detection and Classification Of Rr Lyrae Starsmentioning

confidence: 99%

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Mapping the outer bulge with RRab stars from the VVV Survey

Gran

Minniti

Saito

et al. 2016

A&A

Self Cite

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“…This table, together with later work (e.g. Gonzalez et al 2011;Gerhard et al 2012;Dékány et al 2013;Pietrukowicz et al 2012Pietrukowicz et al , 2015Wegg et al 2013;Cao et al 2013;Vasquez et al 2013;Gran et al 2015;Nataf et al 2015) shows that a large range of bar angles have been suggested. These are generally in the range ∼ 20 o to ∼ 45 o but have ranged from 11.1 ± 0.7 o (Robin et al 2003) to a near spherical distribution (Dékány 2013).…”

Section: Introductionmentioning

confidence: 56%

The age and structure of the Galactic bulge from Mira variables

Catchpole¹,

Whitelock²,

Feast³

et al. 2015

Mon. Not. R. Astron. Soc.

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We report periods and JHKL observations for 648 oxygen-rich Mira variables found in two outer bulge fields at b = −7 o and l = ±8 o and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys, which are concentrated closer to the Galactic centre. Distance moduli are estimated for all these stars. Evidence is given showing that the bulge structure is a function of age. The longer period Miras (log P > 2.6, age ∼ 5 Gyr and younger) show clear evidence of a bar structure inclined to the line of sight in both the inner and outer regions. The distribution of the shorter period (metal-rich globular cluster age) Miras, appears spheroidal in the outer bulge. In the inner region these old stars are also distributed differently from the younger ones and possibly suggest a more complex structure. These data suggest a distance to the galactic centre R 0 , of 8.9 kpc with an estimated uncertainty of ∼ 0.4 kpc. The possible effect of helium enrichment on our conclusions is discussed.

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“…A general purpose classifier that can classify (with a bit lower accuracy) many different variability classes Long et al 2012;Pichara & Protopapas 2013). (Gran et al 2015) from the rest. 5.…”

Section: Introductionmentioning

confidence: 99%

Meta-Classification for Variable Stars

Pichara

Protopapas

León

2016

ApJ

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The need for the development of automatic tools to explore astronomical databases has been recognized since the inception of CCDs and modern computers. Astronomers already have developed solutions to tackle several science problems, such as automatic classification of stellar objects, outlier detection, and globular clusters identification, among others. New scientific problems emerge, and it is critical to be able to reuse the models learned before, without rebuilding everything from the beginning when the sciencientific problem changes. In this paper, we propose a new meta-model that automatically integrates existing classification models of variable stars. The proposed meta-model incorporates existing models that are trained in a different context, answering different questions and using different representations of data. A conventional mixture of expert algorithms in machine learning literature cannot be used since each expert (model) uses different inputs. We also consider the computational complexity of the model by using the most expensive models only when it is necessary. We test our model with EROS-2 and MACHO data sets, and we show that we solve most of the classification challenges only by training a meta-model to learn how to integrate the previous experts.

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Bulge RR Lyrae stars in the VVV tile b201

Cited by 23 publications

References 38 publications

Mapping the outer bulge with RRab stars from the VVV Survey

Mapping the outer bulge with RRab stars from the VVV Survey

The age and structure of the Galactic bulge from Mira variables

Meta-Classification for Variable Stars

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