The inner Galactic bar traced by the VVV survey

O. A. Gonzalez, M. Rejkuba, D. Minniti, M. Zoccali, E. Valenti, R. K. Saito

Resultado de la investigación: Review article

48 Citas (Scopus)

Resumen

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-Ks) 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 Ks0 = 13.4 at l =-10° to Ks0 = 12.4 at l = +10°. We detect a change in the orientation of the bar in the central regions with |l| < 4° at b = ±1°, 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.

Idioma originalEnglish
Número de artículoL14
PublicaciónAstronomy and Astrophysics
Volumen534
DOI
EstadoPublished - 24 oct 2011

Huella dactilar

clumps
longitude
luminosity
inclination
extinction
color
stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Gonzalez, O. A., Rejkuba, M., Minniti, D., Zoccali, M., Valenti, E., & Saito, R. K. (2011). The inner Galactic bar traced by the VVV survey. Astronomy and Astrophysics, 534, [L14]. https://doi.org/10.1051/0004-6361/201117959
Gonzalez, O. A. ; Rejkuba, M. ; Minniti, D. ; Zoccali, M. ; Valenti, E. ; Saito, R. K. / The inner Galactic bar traced by the VVV survey. En: Astronomy and Astrophysics. 2011 ; Vol. 534.
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Gonzalez, OA, Rejkuba, M, Minniti, D, Zoccali, M, Valenti, E & Saito, RK 2011, 'The inner Galactic bar traced by the VVV survey', Astronomy and Astrophysics, vol. 534, L14. https://doi.org/10.1051/0004-6361/201117959

The inner Galactic bar traced by the VVV survey. / Gonzalez, O. A.; Rejkuba, M.; Minniti, D.; Zoccali, M.; Valenti, E.; Saito, R. K.

En: Astronomy and Astrophysics, Vol. 534, L14, 24.10.2011.

Resultado de la investigación: Review article

TY - JOUR

T1 - The inner Galactic bar traced by the VVV survey

AU - Gonzalez, O. A.

AU - Rejkuba, M.

AU - Minniti, D.

AU - Zoccali, M.

AU - Valenti, E.

AU - Saito, R. K.

PY - 2011/10/24

Y1 - 2011/10/24

N2 - 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-Ks) 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 Ks0 = 13.4 at l =-10° to Ks0 = 12.4 at l = +10°. We detect a change in the orientation of the bar in the central regions with |l| < 4° at b = ±1°, 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.

AB - 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-Ks) 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 Ks0 = 13.4 at l =-10° to Ks0 = 12.4 at l = +10°. We detect a change in the orientation of the bar in the central regions with |l| < 4° at b = ±1°, 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.

KW - Galaxy: bulge

KW - Galaxy: structure

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DO - 10.1051/0004-6361/201117959

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