Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253 - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Monthly Notices of the Royal Astronomical Society: Letters Année : 2016

Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253

Aaron Romanowsky
  • Fonction : Auteur
David Martínez-Delgado
  • Fonction : Auteur
Gustavo Morales
  • Fonction : Auteur
Zachary Jennings
  • Fonction : Auteur
R. Jay Gabany
  • Fonction : Auteur
Jean Brodie
  • Fonction : Auteur
Eva Grebel
  • Fonction : Auteur
Johannes Schedler
  • Fonction : Auteur
Michael Sidonio
  • Fonction : Auteur

Résumé

We report the discovery of NGC 253-dw2, a dwarf spheroidal (dSph) galaxy candidate undergoing tidal disruption around a nearby spiral galaxy, NGC 253 in the Sculptor group: the first such event identified beyond the Local Group. The dwarf was found using small-aperture amateur telescopes, and followed up with Suprime-Cam on the 8 m Subaru Telescope in order to resolve its brightest stars. Using g-and R c-band photometry, we detect a red giant branch consistent with an old, metal-poor stellar population at a distance of ∼3.5 Mpc. From the distribution of likely member stars, we infer a highly elongated shape with a semimajor axis half-light radius of (2 ± 0.4) kpc. Star counts also yield a luminosity estimate of ∼2 × 10 6 L ,V (M V ∼ −10.7). The morphological properties of NGC 253-dw2 mark it as distinct from normal dSphs and imply ongoing disruption at a projected distance of ∼50 kpc from the main galaxy. Our observations support the hierarchical paradigm wherein massive galaxies continuously accrete less massive ones, and provide a new case study for dSph infall and dissolution dynamics. We also note the continued efficacy of small telescopes for making big discoveries.
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Dates et versions

hal-03156542 , version 1 (02-03-2021)

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Aaron Romanowsky, David Martínez-Delgado, Nicolas Martin, Gustavo Morales, Zachary Jennings, et al.. Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253. Monthly Notices of the Royal Astronomical Society: Letters, 2016, 457 (1), pp.L103-L107. ⟨10.1093/mnrasl/slv207⟩. ⟨hal-03156542⟩
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