Ionized Gas Motions and the Structure of Feedback near a Forming Globular Cluster in NGC 5253

We observed Brackett 4.05 m emission toward the supernebula in NGC 5253 with NIRSPEC on Keck II in adaptive optics mode, NIRSPAO, to probe feedback from its exciting embedded super star cluster (SSC). NIRSPEC's Slit-viewing Camera was simultaneously used to image the K-band continuum at ∼0 1 re...

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Bibliographic Details
Published in:The Astrophysical journal 2018-06, Vol.860 (1), p.47
Main Authors: Cohen, Daniel P., Turner, Jean L., Consiglio, S. Michelle, Martin, Emily C., Beck, Sara C.
Format: Article
Language:English
Subjects:
Adaptive optics
Astrophysics
Emission spectra
Feedback
Galaxies
galaxies: dwarf
galaxies: individual (NGC 5253)
galaxies: star clusters: general
galaxies: star formation
galaxies: starburst
H II regions
Massive stars
Milky Way
Molecular clouds
Optics
Outflow
Radiative cooling
regions
Star clusters
Stellar winds
Velocity
Wind
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Summary:We observed Brackett 4.05 m emission toward the supernebula in NGC 5253 with NIRSPEC on Keck II in adaptive optics mode, NIRSPAO, to probe feedback from its exciting embedded super star cluster (SSC). NIRSPEC's Slit-viewing Camera was simultaneously used to image the K-band continuum at ∼0 1 resolution. We register the IR continuum with HST imaging, and find that the visible clusters are offset from the K-band peak, which coincides with the Br peak of the supernebula and its associated molecular cloud. The spectra of the supernebula exhibit Br emission with a strong, narrow core. The linewidths are 65-76 km s−1, FWHM, comparable to those around individual ultra-compact H ii regions within our Galaxy. A weak, broad (FWHM 150-175 km s−1) component is detected on the base of the line, which could trace a population of sources with high-velocity winds. The core velocity of Br emission shifts by +13 km s−1 from NE to SW across the supernebula, possibly indicating a bipolar outflow from an embedded object or a link to a foreground redshifted gas filament. The results can be explained if the supernebula comprises thousands of ionized wind regions around individual massive stars, stalled in their expansion due to critical radiative cooling and unable to merge to drive a coherent cluster wind. Based on the absence of an outflow with large mass loss, we conclude that feedback is currently ineffective at dispersing gas, and the SSC retains enriched material out of which it may continue to form stars.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aac170