Título:
Inferring stellar densities with flexible models. I. The distribution of RR Lyrae in the Milky Way with Gaia DR3
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Autor:
Lucey, Madeline
Mateu, Cecilia
Price-Whelan, A. M.
Hogg, David W.
Rix, Hans-Walter
Sanderson, Robyn E.
Mateu, Cecilia
Price-Whelan, A. M.
Hogg, David W.
Rix, Hans-Walter
Sanderson, Robyn E.
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Tipo de documento:
Artículo
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Palabras clave:
Milky Way Galaxy
RR Lyrae variable stars
Milky Way stellar halo
RR Lyrae variable stars
Milky Way stellar halo
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Año de publicación:
2026
Contenido:
Resumen:
Understanding the formation and evolutionary history of the Milky Way requires detailed mapping of its stellar
components, which preserve fossil records of the Galaxy’s assembly through cosmic time. RR Lyrae stars are
particularly well suited for this endeavor, as they are old, standard candle variables that probe the Galaxy’s
earliest formation epochs. In this work, we employ a hierarchical Bayesian Gaussian Mixture Model (GMM) to
characterize the three-dimensional density distribution of RR Lyrae stars in the Milky Way over the galactocentric
radius (R) of ≈0.2–120 kpc. This approach provides a flexible framework for modeling complex stellar distributions, particularly in the inner Galaxy where the bulge, disk, and halo components overlap. Our analysis reveals that the inner Galaxy (R ≲ 10 kpc) is dominated by a distinct prolate stellar population with axis ratio q = 1.31. Consistent with previous work, we find the halo follows a r−4 power-law profile that flattens within 12 kpc of the Galactic center. We also confirm the outer halo (R ≳ 10 kpc) is oblate q = 0.70 with a tilt angle of 18º. We report for the first time that this tilt aligns the halo major axis in the direction of the Sagittarius dwarf galaxy. These results establish GMMs as an effective and flexible tool for modeling Galactic structure and provide new constraints on the distribution of old stars in the inner Galaxy.
Descripción:
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Editorial:
Institute of Physics
EN:
The Astronomical Journal, 2026, 171(4): 249.
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Citación:
Lucey, M, Mateu, C, Price-Whelan, A [y otros autores]. "Inferring stellar densities with flexible models. I. The distribution of RR Lyrae in the Milky Way with Gaia DR3". The Astronomical Journal. [en línea] 2026, 171(4) :249. 11 h. DOI: 10.3847/1538-3881/ae4aaa
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ISSN:
0004-6256
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Licencia:
Licencia Creative Commons Atribución (CC - By 4.0)
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| Ficheros | Descripción | Tamaño | Formato | ||
|---|---|---|---|---|---|
| 10.3847.1538-3881.ae4aaa.pdf | — | 3.79 MB | Adobe PDF |