Bibcode
Monelli, M.; Fiorentino, G.; Bernard, E. J.; Martínez-Vázquez, C. E.; Bono, G.; Gallart, C.; Dall’Ora, M.; Stetson, P. B.
Referencia bibliográfica
The Astrophysical Journal, Volume 842, Issue 1, article id. 60, 18 pp. (2017).
Fecha de publicación:
6
2017
Revista
Número de citas
18
Número de citas referidas
17
Descripción
We present the discovery of 1568 RR Lyrae stars in three of the most
luminous M31 satellites: And VII (573), NGC 147 (177), and NGC 185
(818). We use their properties to study the formation history of Local
Group spiral haloes, and in particular, to infer about the nature of
their possible building blocks by comparison with available data for RR
Lyrae stars in the halo and in a sample of satellites of M31 and the
Milky Way. We find that the brightest satellites and the halos of both
galaxies host a number of High Amplitude Short Period (HASP) RR Lyrae
variable stars, which are missing in the faintest satellites. HASP
variable stars have been shown by Fiorentino et al. to be tracers of a
population of stars as metal-rich as [Fe/H] ≃ ‑1.5 and older
than ≃ 10 {Gyr}. This suggests that the metal-rich M31 and MW halo
component, which manifests through the HASP phenomenon, comes from
massive dwarf galaxy building blocks, as the low-mass dwarfs did not
chemically enrich fast enough to produce them. All detected variable
stars are new discoveries; in particular, this work presents the first
detections of RR Lyrae stars in And VII. Moreover, a number of candidate
Anomalous Cepheids, and binary and long-period variable stars have been
detected. We provide pulsation properties (period, amplitude, mean
magnitude), light curves, and time series photometry for all of the
variable stars in the three galaxies.
Based on observations made with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated by
the Association of Universities for Research in Astronomy, Inc., under
NASA contract NAS 5-26555. These observations are associated with
programs #10430 and #11724.
Proyectos relacionados
Evolución Galáctica en el Grupo Local
La formación y evolución de galaxias es un problema fundamental en Astrofísica. Su estudio requiere “viajar atrás en el tiempo”, para lo cual hay dos enfoques complementarios. El mas extendido consiste en analizar las propiedades de las galaxias a diferentes distancias cosmológicas. Nuestro equipo se concentra en el otro enfoque, denominado
Matteo
Monelli