Satellite accretion in action

• Verfasst von: Romanowsky, Aaron J. [VerfasserIn]
• Verfasst von: Martínez-Delgado, David [VerfasserIn]
• Verfasst von: Morales, Gustavo [VerfasserIn]
• Verfasst von: Grebel, Eva K. [VerfasserIn]
• Titel: Satellite accretion in action
• Titelzusatz: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253
• Verf.angabe: Aaron J. Romanowsky, D. Martinez-Delgado, Nicolas F. Martin, Gustavo Morales, Zachary G. Jennings, R. Jay GaBany, Jean P. Brodie, Eva K. Grebel, Johannes Schedler, and Michael Sidonio
• Fussnoten: Gesehen am 08.11.2017
• Titel Quelle: Enthalten in: De.arxiv.org
• Jahr Quelle: 2015
• Band/Heft Quelle: (2015) Artikel-Nummer 1512.03815, 6 Seiten
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1565126092

Abstract

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 semi-major axis half-light radius of (2 +/- 0.4) kpc. Star counts also yield a luminosity estimate of ~ 2x10^6 L_Sun,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 continously 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.