The Extinction Toward the Galactic Bulge From Rr Lyrae Stars

Kunder, Andrea; Popowski, Piotr; Cook, K. H.; Chaboyer, Brian

doi:10.1088/0004-6256/135/2/631

Cited by 38 publications

(53 citation statements)

References 37 publications

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“…A Gaussian fit to the (J − K s ) color distribution is then used to determine the mean color of the red clump. (Sumi 2004;Kunder et al 2008;Zoccali et al 2008), we obtain a dereddened mean color of (J − K s ) 0 = 0.68 for the RC stars in this region. We use this value as a reference for the intrinsic mean color of the RC, and its difference with respect to the measured RC color in any other region is an indicator of the extinction, given by E(J − K s ).…”

Section: Mean Color Of the Galactic Bulge Red Clumpmentioning

confidence: 69%

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Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS

Gonzalez

Rejkuba

Zoccali

et al. 2012

A&A

331

494

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Context. The Milky Way bulge is the nearest galactic bulge and the most readily accessible laboratory for studies of stellar populations in spheroids based on individual stellar abundances and kinematics. These studies are challenged by the strongly variable and often large extinction on a small spatial scale. Aims. We use the Vista Variables in the Via Lactea (VVV) ESO public survey data to measure extinction values in the complete area of the Galactic bulge covered by the survey at high resolution. Methods. We derive reddening values using the method described in Paper I. This is based on measuring the mean (J − K s ) color of red clump giants in small subfields of 2 × 2 to 6 × 6 in the following bulge area:• . To determine the reddening values E(J − K s ) for each region, we measure the RC color and compare it to the (J − K s ) color of RC stars measured in Baade's Window, for which we adopt E(B − V) = 0.55. This allows us to construct a reddening map sensitive to small-scale variations minimizing the problems arising from differential extinction. Results. The significant reddening variations are clearly observed on spatial scales as small as 2 . We find good agreement between our extinction measurements and Schlegel maps in the outer bulge, but, as already stated in the literature the Schlegel maps are unreliable for regions within |b| < ∼ 6• . In the inner regions, we compare our results with maps derived from DENIS and Spitzer surveys. While we find good agreement with other studies in the corresponding overlapping regions, our extinction map is of higher quality owing to both its higher resolution and a more complete spatial coverage of the bulge. We investigate the importance of differential reddening and demonstrate the need for high spatial resolution extinction maps for detailed studies of bulge stellar populations and structure. Conclusions. We present the first extinction map covering uniformly ∼315 sq. deg. of the Milky Way bulge at high spatial resolution. We consider a 30 arcmin window at a latitude of b = −4• , which corresponds to a frequently studied low extinction window, the so-called Baade's Window, and find that its A Ks values can vary by up to 0.1 mag. Larger extinction variations are observed at lower Galactic latitudes. The extinction variations on scales of up to 2 −6 must be taken into account when analyzing the stellar populations of the Galactic bulge.

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Section: Mean Color Of the Galactic Bulge Red Clumpmentioning

confidence: 69%

“…Other important extinction maps are available with a partial coverage of the GB such as those of Kunder et al (2008) and Sumi (2004). However, for detailed studies of the GB, a high resolution and homogeneous extinction map covering the complete area of interest is missing.…”

Section: Introductionmentioning

confidence: 99%

Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS

Gonzalez

Rejkuba

Zoccali

et al. 2012

A&A

331

494

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“…In the study of RR Lyrae in the bulge from Kunder et al (2008), variations with respect to the standard reddening law were observed in a few directions. However, they conclude that, on average, the extinction law of • , 30…”

Section: Discussionmentioning

confidence: 99%

The inner Galactic bar traced by the VVV survey

Gonzalez

Rejkuba

Minniti

et al. 2011

A&A

102

116

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Aims. We use the VVV survey observations in bulge regions close to the Galactic plane to trace the bar inclination at the Galactic latitude b ∼ ±1 and to investigate a distinct structure in the inner regions of the bar that was previously detected at positive latitude (b = +1). Methods. We use the (J − K s ) colors of the red clump stars to obtain reddening values on 6 × 6 arcmin scale, minimizing the problems arising from differential extinction. Dereddened magnitudes are then used to build the luminosity function of the bulge in regions of ∼0.4 sq deg to obtain the mean red clump magnitudes. These are used as distance indicators to trace the bar structure.Results. The luminosity function clearly shows the red clump mean magnitude variation with longitude, as expected from a large scale bar oriented towards us at positive Galactic longitude, with a dereddened magnitude varying from K s 0 = 13.4 at l = −10• to K s 0 = 12.4 at l = +10• . We detect a change in the orientation of the bar in the central regions with |l| < 4• , in agreement with results obtained at positive latitudes by other authors. Our results are based on a different dataset and at different latitude, which shows that this change in the bar orientation is real. This suggests that there is an inner structure distinct to the large-scale Galactic bar, with a different orientation angle. This inner structure could be a secondary, inner bar, with a semi-major axis of ∼500 pc that is symmetric with respect to the Galactic plane.

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“…This class of variable stars was used to characterize various components of the Milky Way, including the halo (Vivas & Zinn 2006;Helmi 2008;Miceli et al 2008;Helmi et al 2011;Drake et al 2014, etc. ), the bulge (Alcock et al 2000;Kunder et al 2008;Dékány et al 2013;Pietrukowicz et al 2015;Gran et al 2016, etc. ), the Solar neighborhood (Layden 1994(Layden , 1998, and the outer thick disk toward the anticenter (Sesar et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Characterization of the VVV Survey RR Lyrae Population across the Southern Galactic Plane

Minniti

Dékány

Majaess

et al. 2017

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Deep near-IR images from the VISTA Variables in the Vía Láctea (VVV) Survey were used to search for RR Lyrae stars in the Southern Galactic plane. A sizable sample of 404 RR Lyrae of type ab stars was identified across a thin slice of the fourth Galactic quadrant (295°< ℓ < 350°, −2°.24 < b < −1°.05). The sample's distance distribution exhibits a maximum density that occurs at the bulge tangent point, which implies that this primarily Oosterhoff type I population of RRab stars does not trace the bar delineated by their red clump counterparts. The bulge RR Lyrae population does not extend beyond ℓ∼340°, and the sample's spatial distribution presents evidence of density enhancements and substructure that warrants further investigation. Indeed, the sample may be employed to evaluate Galactic evolution models, and is particularly lucrative since half of the discovered RR Lyrae are within reach of Gaia astrometric observations.

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The Extinction Toward the Galactic Bulge From Rr Lyrae Stars

Cited by 38 publications

References 37 publications

Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS

Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS

The inner Galactic bar traced by the VVV survey

Characterization of the VVV Survey RR Lyrae Population across the Southern Galactic Plane

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