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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Integral field unit observations of NGC 891: Kinematics of the diffuse ionized gas halo
Astrophysical Journal, Volume 647, No. 2 I, Year 2006
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Description
We present high and moderate spectral resolution spectroscopy of diffuse ionized gas (DIG) emission in the halo of NGC 891. The data were obtained with the SparsePak integral field unit at the WIYN Observatory. The wavelength coverage includes the [N II] λλ6548, 6583, Hα, and [S II] λλ6716, 6731 emission lines. Position-velocity (PV) diagrams, constructed using spectra extracted from four SparsePak pointings in the halo, are used to examine the kinematics of the DIG. Using two independent methods, a vertical gradient in azimuthal velocity is found to be present in the northeast quadrant of the halo, with magnitude approximately 15-18 km s-1 kpc, in agreement with results from H I observations. The kinematics of the DIG suggests that this gradient begins at approximately 1 kpc above the midplane. In another part of the halo, the southeast quadrant, the kinematics is markedly different and suggest rotation at about 175 km s-1, much slower than the disk but with no vertical gradient. We use an entirely ballistic model of disk-halo flow in an attempt to reproduce the kinematics observed in the northeast quadrant. Analysis shows that the velocity gradient predicted by the ballistic model is far too shallow. Based on intensity cuts made parallel to the major axis in the ballistic model and an Hα image of NGC 891 from the literature, we conclude that the DIG halo is much more centrally concentrated than the model, suggesting that hydrodynamics dominate over ballistic motion in shaping the density structure of the halo. Velocity dispersion measurements along the minor axis of NGC 891 seem to indicate a lack of radial motions in the halo, but the uncertainties do not allow us to set firm limits. © 2006. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Heald, George H.
United States, Albuquerque
The University of new Mexico
United States, Tucson
National Optical Astronomy Observatory
Rand, Richard J.
United States, Albuquerque
The University of new Mexico
United States, Tucson
National Optical Astronomy Observatory
Benjamin, Robert A.
United States, Whitewater
University of Wisconsin-whitewater
Bershady, Matthew A.
United States, Madison
University of Wisconsin-madison
Statistics
Citations: 64
Authors: 4
Affiliations: 4
Identifiers
Doi:
10.1086/505464
ISSN:
0004637X
Research Areas
Environmental
Health System And Policy