The Pristine dwarf galaxy survey - IV. Probing the outskirts of the dwarf galaxy Boötes I

Longeard, Nicolas; Jablonka, Pascale; Arentsen, Anke; Thomas, Guillaume F.; Aguado, David S.; Carlberg, Raymond G.; Lucchesi, Romain; Malhan, Khyati; Martin, Nicolas; McConnachie, Alan W.; Navarro, Julio F.; Sánchez-Janssen, Rubén; Sestito, Federico; Starkenburg, Else; Yuan, Zhen
Referencia bibliográfica

Monthly Notices of the Royal Astronomical Society

Fecha de publicación:
10
2022
Número de autores
15
Número de autores del IAC
1
Número de citas
21
Número de citas referidas
18
Descripción
We present a new spectroscopic study of the dwarf galaxy Boötes I (Boo I) with data from the Anglo-Australian Telescope and its AAOmega spectrograph together with the Two Degree Field multi-object system. We observed 36 high-probability Boo I stars selected using Gaia Early Data Release 3 proper motions and photometric metallicities from the Pristine survey. Out of those, 27 are found to be Boo I stars, resulting in an excellent success rate of 75 per cent at finding new members. Our analysis uses a new pipeline developed to estimate radial velocities and equivalent widths of the calcium triplet lines from Gaussian and Voigt line profile fits. The metallicities of 16 members are derived, including 3 extremely metal-poor stars ([Fe/H] < -3.0), which translates into a success rate of 25 per cent at finding them with the combination of Pristine and Gaia. Using the large spatial extent of our new members that spans up to 4.1 half-light radii and spectroscopy from the literature, we find a systemic velocity gradient of 0.40 ± 0.10 km s-1 arcmin-1 and a small but resolved metallicity gradient of -0.008 ± 0.003 dex arcmin-1. Finally, we show that Boo I is more elongated than previously thought with an ellipticity of ϵ = 0.68 ± 0.15. Its velocity and metallicity gradients as well as its elongation suggest that Boo I may have been affected by tides, a result supported by direct dynamical modelling.
Proyectos relacionados
Una vista de nuestra galaxia, la Vía Láctea, con sus vecinos cercanos,  las Nubes de Magallanes
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