Bibcode
DOI
Balcells, Marc; van Gorkom, J. H.; Sancisi, Renzo; del Burgo, Carlos
Referencia bibliográfica
The Astronomical Journal, Volume 122, Issue 4, pp. 1758-1769.
Fecha de publicación:
10
2001
Número de citas
33
Número de citas referidas
28
Descripción
Very Large Array7 neutral hydrogen observations of the shell elliptical
galaxy NGC 3656 reveal an edge-on, warped minor-axis gaseous disk
(MHI~2×109 Msolar) extending 7
kpc. H I is also found outside the optical image, on two complexes to
the northeast and northwest that seem to trace one or two tidal tails,
or possibly an outer broken H I disk or ring. These complexes link with
the outer edges of the inner disk and appear displaced with respect to
the two optical tails in the galaxy. The disk kinematics is strongly
lopsided, suggesting recent or ongoing accretion. Integral-field optical
fiber spectroscopy at the region of the bright southern shell of NGC
3656 has provided a determination of the stellar velocities of the
shell. The shell, at 9 kpc from the center, has traces of H I with
velocities bracketing the stellar velocities, providing evidence for a
dynamical association of H I and stars at the shell. Within the errors
the stars have systemic velocity, suggesting a possible phase-wrapping
origin for the shell. We probed a region of
40'×40' (480 kpc×480 kpc)×1160
km s-1 down to an H I mass sensitivity (6 σ) of
3×107 Msolar and detect five dwarf galaxies
with H I masses ranging from 2×108 to
2×109 Msolar, all within 180 kpc of NGC 3656
and all within the velocity range (450 km s-1) of the H I of
NGC 3656. The dwarfs had been previously cataloged, but none had a known
redshift. For the NGC 3656 group to be bound requires a total mass of
(3-7.4)×1012 Msolar, yielding a
mass-to-light ratio from 125 to 300. The overall H I picture presented
by NGC 3656 supports the hypothesis of a disk-disk merger origin or
possibly an ongoing process of multiple mergers with nearby dwarfs.
Based on observations made with the William Herschel Telescope operated
on the island of La Palma by the Isaac Newton Group of Telescopes in the
Spanish Observatorio del Roque de los Muchachos of the Instituto de
Astrofísica de Canarias.