Analysing the structure of the bulge with Mira variables

Chrobáková, Ž.; López-Corredoira, M.; Garzón, F.
Referencia bibliográfica

Astronomy and Astrophysics

Fecha de publicación:
Número de autores
Número de autores del IAC
Número de citas
Número de citas referidas
Context. The Galactic bulge at latitude 4 < |b|(deg) < 10 was claimed to show an X-shape, which means that stellar density distributions along the line of sight have a double peak. However, this double peak is only observed with the red-clump population, and doubt has been cast on its use as a perfect standard candle. As such, a boxy bulge without an X-shape is not discarded.
Aims: We aim to constrain the shape of the bulge making use of a different population: Mira variables from the new Optical Gravitational Lensing Experiment data release, OGLE-IV, with an average age of 9 Gyr.
Methods: We analysed an area of the bulge far from the plane, where we fitted the density of the Miras with boxy bulge and X-shaped bulge models and calculated the probability of each model.
Results: We find that the probability of a boxy bulge fitting the data is p = 0.19, whereas the probability for the X-shaped bulge is only p = 2.85 × 10−6 (equivalent to a tension of the model with the data of a 4.7σ level). Therefore, the boxy bulge model seems to be more appropriate for describing the Galactic bulge, although we cannot exclude any model with complete certainty.
Proyectos relacionados
Cúmulo Globular NGC 2808
Vía Láctea y galaxias cercanas

El objetivo general del Proyecto es el estudio de la estructura, historia evolutiva y proceso de formación de galaxias a través de sus poblaciones estelares resueltas, tanto a partir de fotometría como espectroscopia. El proyecto puede dividirse en cuatro líneas principales: I. Historia de formación estelar en el Grupo Local. El objetivo de esta

López Corredoira