期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 442, 期 4, 页码 3544-3564出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stu1074
关键词
galaxies: individual: NGC 4651; galaxies: interactions; galaxies: kinematics and dynamics
资金
- Marie Curie Actions of the European Commission (FP7-COFUND)
- European Commission [PITN-GA-2009-238356]
- National Science Foundation [AST-0909237, AST-1211995]
- W.M. Keck Foundation
- NSF [AST-0071048]
- NASA [NAS5-26555]
- NASA Office of Space Science [NNX13AC07G]
- STFC [ST/L000695/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/L000695/1] Funding Source: researchfish
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1211995] Funding Source: National Science Foundation
We study the dynamics of faint stellar substructures around the Umbrella Galaxy, NGC 4651, which hosts a dramatic system of streams and shells formed through the tidal disruption of a nucleated dwarf elliptical galaxy. We elucidate the basic characteristics of the system (colours, luminosities, stellar masses) using multiband Subaru/Suprime-Cam images. The implied stellar mass ratio of the ongoing merger event is similar to 1:50. We identify candidate kinematic tracers (globular clusters, planetary nebulae, H ii regions) and follow up a subset with Keck/DEIMOS (DEep Imaging Multi-object Spectrograph) spectroscopy to obtain velocities. We find that 15 of the tracers are likely associated with halo substructures, including the probable stream progenitor nucleus. These objects delineate a kinematically cold feature in position-velocity phase space. We model the stream using single test particle orbits, plus a rescaled pre-existing N-body simulation. We infer a very eccentric orbit with a period of similar to 0.35 Gyr and turning points at similar to 2-4 and similar to 40 kpc, implying a recent passage of the satellite through the disc, which may have provoked the visible disturbances in the host galaxy. This work confirms that the kinematics of low surface brightness substructures can be recovered and modelled using discrete tracers - a breakthrough that opens up a fresh avenue for unravelling the detailed physics of minor merging.
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