Bibcode
DOI
Arribas, S.; Mediavilla, E.; del Burgo, C.; García-Lorenzo, B.
Bibliographical reference
The Astrophysical Journal, Volume 511, Issue 2, pp. 680-685.
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2
1999
Journal
Citations
10
Refereed citations
9
Description
We present two-dimensional optical spectroscopy of the central region
(9.4"x12.2") of the Seyfert 1 ring galaxy NGC 985 obtained with an
optical fiber system (two-dimensional Fiber ISIS System). The 95 spectra
presented here include the Hβ-[O III] lambdalambda4959, 5007
emission lines and the Mg I b absorption lines, which permit the study
of the distribution and kinematics of the ionized gas and the stars in
two dimensions. In agreement with the results of other authors, the
continuum maps show the presence of two maxima: the bright Seyfert 1
nucleus and a second nucleus located about 3.7" to the northwest. These
observations confirm that this second nucleus is an extragalactic object
at the same redshift as that of NGC 985. These observations indicate an
anisotropic distribution of the ionized gas around the Seyfert nucleus.
Despite this, the velocity field of the ionized gas shows a rather
regular pattern, its general kinematic properties being similar to those
found in other unperturbed spiral Seyfert galaxies. Many of the spectra
in the region between the Seyfert and the secondary nucleus have
asymmetric and relatively broad [O III] emission-line profiles. The
kinematic center of the stellar velocity field is located in the
neighborhood of the Seyfert nucleus, suggesting that this nucleus is
related to the main stellar component. Therefore, these observations
support the hypothesis that NGC 985 is the result of a two-galaxy
collision in which the intruder (elliptical or spheroidal) galaxy would
be what is now the secondary nucleus, while the Seyfert activity is
associated with the nucleus of the primary disk galaxy. In spite of the
strong disruption that defines the large-scale morphology of NGC 985,
the stellar and ionized gas kinematics do not appear significantly
perturbed in the circumnuclear region.