Extinction law and stellar mass in the Nuclear Bulge from kinematically-selected red clump stars

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Main Authors: Navarro, Á. Valenzuela, Zoccali, M., Valenti, E., Ramos, R. Contreras, Rojas-Arriagada, A., Luna, A., Albarracín, R., Gallart, C., Carvajal, J. Olivares, Gran, F., Salvo-Guajardo, C., Nandakumar, G., Renzini, A.
Format: Preprint
Published: 2026
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author Navarro, Á. Valenzuela
Zoccali, M.
Valenti, E.
Ramos, R. Contreras
Rojas-Arriagada, A.
Luna, A.
Albarracín, R.
Gallart, C.
Carvajal, J. Olivares
Gran, F.
Salvo-Guajardo, C.
Nandakumar, G.
Renzini, A.
author_facet Navarro, Á. Valenzuela
Zoccali, M.
Valenti, E.
Ramos, R. Contreras
Rojas-Arriagada, A.
Luna, A.
Albarracín, R.
Gallart, C.
Carvajal, J. Olivares
Gran, F.
Salvo-Guajardo, C.
Nandakumar, G.
Renzini, A.
contents The Nuclear Bulge of the Milky Way harbors stellar populations that provide crucial insights into galaxy formation processes and serve as a nearby analog for understanding bulge formation in external galaxies. However, detailed studies of this region are severely hampered by extreme and highly variable interstellar extinction, which obscures the intrinsic stellar properties and impedes accurate stellar mass determinations. Our goal is to measure the extinction law towards the Nuclear Bulge and to estimate its stellar density. We developed a method to determine the extinction law towards the Nuclear Bulge by kinematically selecting red clump stars belonging to this region. We created a high-spatial resolution reddening map, and computed stellar mass with completeness-corrected red clump star counts, scaled from empirical measurements. We find a total-to-selective extinction ratio of $\mathrm{A_K/{E_{H-K}} = 1.259 \pm 0.074}$, and an extinction ratio of $\mathrm{A_H/A_K = 1.794 \pm 0.046}$, which are consistent with previous works. The high-spatial resolution reddening map shows clear filamentary structures, and a gradient in the extinction over the giant molecular cloud G0.253+0.016 (i.e., the Brick). From the star counts, we measured a stellar mass of $\mathrm{12.2~\pm2.6\times10^8~M_{\odot}}$ for the Nuclear Bulge, in agreement with other mass estimates.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00223
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Extinction law and stellar mass in the Nuclear Bulge from kinematically-selected red clump stars
Navarro, Á. Valenzuela
Zoccali, M.
Valenti, E.
Ramos, R. Contreras
Rojas-Arriagada, A.
Luna, A.
Albarracín, R.
Gallart, C.
Carvajal, J. Olivares
Gran, F.
Salvo-Guajardo, C.
Nandakumar, G.
Renzini, A.
Astrophysics of Galaxies
The Nuclear Bulge of the Milky Way harbors stellar populations that provide crucial insights into galaxy formation processes and serve as a nearby analog for understanding bulge formation in external galaxies. However, detailed studies of this region are severely hampered by extreme and highly variable interstellar extinction, which obscures the intrinsic stellar properties and impedes accurate stellar mass determinations. Our goal is to measure the extinction law towards the Nuclear Bulge and to estimate its stellar density. We developed a method to determine the extinction law towards the Nuclear Bulge by kinematically selecting red clump stars belonging to this region. We created a high-spatial resolution reddening map, and computed stellar mass with completeness-corrected red clump star counts, scaled from empirical measurements. We find a total-to-selective extinction ratio of $\mathrm{A_K/{E_{H-K}} = 1.259 \pm 0.074}$, and an extinction ratio of $\mathrm{A_H/A_K = 1.794 \pm 0.046}$, which are consistent with previous works. The high-spatial resolution reddening map shows clear filamentary structures, and a gradient in the extinction over the giant molecular cloud G0.253+0.016 (i.e., the Brick). From the star counts, we measured a stellar mass of $\mathrm{12.2~\pm2.6\times10^8~M_{\odot}}$ for the Nuclear Bulge, in agreement with other mass estimates.
title Extinction law and stellar mass in the Nuclear Bulge from kinematically-selected red clump stars
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2605.00223