Arcs and Bridges in the Interacting Galaxies NGC 5775/NGC 5774
Abstract
We present the first neutral hydrogen images of the edge-on, IR-bright spiral galaxy, NGC 5775, and its companion, NGC 5774. Several H I arcs and extensions are observed out to ~8 kpc from the plane of NGC 5775 and resemble the Heiles shells observed in the Milky Way and similar features seen in NGC 891 and NGC 3079. NGC 5775 and NGC 5774 are clearly interacting, with gas apparently transferring from NGC 5774 to NGC 5775 along two connecting H I bridges. Faint optical emission as well as radio continuum emission are also present along the bridges, but no strong optical distortions or tidal tails are associated with either galaxy. We suggest that this system may be in the early stages of a merger. The parameters of the H I velocity and density distributions of NGC 5775 have been modeled using the technique of Irwin & Seaquist (1991) for edge-on galaxies. The density distributions are best described by a Gaussian ring in the galaxy plane and an exponential distribution perpendicular to the plane. The velocity distribution is well fitted with a classical Brandt rotation curve, but the fits are not particularly sensitive to the shape of this curve. An internal velocity dispersion (representing all internal sources of noncircular velocities) of order 24 km s^-1^ is also required. NGC 5774, of low inclination, has been modeled from the moments of the H I distribution. Its internal velocity dispersion is also relatively high, and high-velocity dispersion knots are also present.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1994
- DOI:
- 10.1086/174349
- Bibcode:
- 1994ApJ...429..618I
- Keywords:
-
- Astronomical Models;
- Density Distribution;
- Galactic Structure;
- Hydrogen Atoms;
- Interacting Galaxies;
- Junctions;
- Kinematics;
- Plasma Jets;
- Starburst Galaxies;
- Velocity Distribution;
- Calibrating;
- Fourier Transformation;
- Images;
- Light Emission;
- Mapping;
- Ultraviolet Radiation;
- Very Large Array (Vla);
- Astrophysics;
- GALAXIES: INTERACTIONS;
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 5774;
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 5775;
- GALAXIES: KINEMATICS AND DYNAMICS;
- GALAXIES: STRUCTURE;
- RADIO LINES: GALAXIES