For refcode 2001AJ....122.2969H: Retrieve 5 NED objects in this reference. Please click here for ADS abstract
NED Abstract
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2001AJ....122.2969H
HIGH-RESOLUTION H I MAPPING OF NGC 4038/39 ("THE ANTENNAE") AND ITS TIDAL
DWARF GALAXY CANDIDATES
J. E. HIBBARD
National Radio Astronomy Observatory,1 520 Edgemont Road, Charlottesville,
VA 22903; jhibbard@nrao.edu
J. M. VAN DER HULST
Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen,
Netherlands; vdhulst@astro.rug.nl
J. E. BARNES
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive,
Honolulu, HI 96822; barnes@ifa.hawaii.edu
AND
R. M. RICH
Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1562;
rmr@astro.ucla.edu
Received 2001 April 30; accepted 2001 August 27
ABSTRACT
We present new VLA C + D array H I observations and optical and
near-infrared imaging of the well-known interacting system NGC 4038/39,
"The Antennae." At low spatial resolution (~40"), the radio data reach a
limiting column density of ~10^19^ cm^-2^ (2.5 {sigma}), providing
significantly deeper mapping of the tidal features than afforded by
earlier H I maps. At relatively high spatial resolution (~10"), the radio
data reveal a wealth of gaseous substructure both within the main bodies
of the galaxies and along the tidal tails. In agreement with previous H I
studies, we find that the northern tail has H I along its outer length but
none along its base. We suggest that the H I at the base of this tail has
been ionized by massive stars in the disk of NGC 4038. The gas in the
southern tail has a bifurcated structure, with one filament lying along
the optical tail and another running parallel to it but with no optical
counterpart. The two filaments join just before the location of several
star-forming regions near the end of the tail. The H I velocity field at
the end of the tail is dominated by strong velocity gradients, which
suggests that at this location the tail is bending away from us. We
delineate and examine two regions within the tail previously identified as
possible sites of a so-called tidal dwarf galaxy condensing out of the
expanding tidal material. The tail velocity gradients mask any clear
kinematic signature of a self-gravitating condensation in this region. A
dynamical analysis suggests that there is not enough mass in gas alone for
either of these regions to be self-gravitating. Conversely, if they are
bound they require a significant contribution to their dynamical mass from
evolved stars or dark matter. Even if there are no distinct dynamical tidal
entities, it is clear that there is a unique concentration of gas, stars,
and star-forming regions within the southern tail: the H I channel maps
show clear evidence for a significant condensation near the tail
star-forming regions, with the single-channel H I column densities higher
than anywhere else in the system, including within the main disks. Finally,
the data reveal H I emission associated with the edge-on "superthin" Scd
galaxy ESO 572-G045, which lies just beyond the southern tidal tail of
The Antennae, showing it to be a companion system.
Key words: galaxies: evolution - galaxies: individual (NGC 4038/39) -
galaxies: interactions - galaxies: ISM - galaxies: kinematics and dynamics
- galaxies: peculiar
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