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

• DOI: 10.1093/mnras/stac1827
• Publication Date: 2022-07-05T22:07:36Z
• Authors: Nicolas Longeard; Pascale Jablonka; Anke Arentsen; Guillaume F Thomas; David S Aguado; Raymond G Carlberg; Romain Lucchesi; Khyati Malhan; Nicolas Martin; Alan W McConnachie; Julio F Navarro; Rubén Sánchez-Jan...; Federico Sestito; Else Starkenburg; Zhen Yuan
• Keywords: Radial velocity

We present a new spectroscopic study of the dwarf galaxy Bootes I (Boo I) with data from Anglo-Australian Telescope and its AAOmega spectrograph together Two Degree Field multi-object system. observed 36 high-probability Boo stars selected using Gaia Early Data Release 3 proper motions photometric metallicities Pristine survey. Out those, 27 are found to be I's stars, resulting in an excellent success rate 75% at finding members. Our analysis uses pipeline developed estimate radial velocities equivalent widths calcium triplet lines Gaussian Voigt line profile fits. The 16 members derived, including extremely metal-poor ([Fe/H] < -3.0), which translates into 25% them combination Gaia. Using large spatial extent our that spans up 4.1 half-light radii spectroscopy literature, we find systemic velocity gradient 0.40 +/- 0.10 km/s/arcmin small but resolved metallicity -0.008 0.003 dex/arcmin. Finally, show is more elongated than previously thought ellipticity epsilon = 0.68 0.15. Its gradients as well elongation suggest may have been affected by tides, result supported direct dynamical modelling.