NGC 3448 revisited - A combined optical, radio, and UV investigation

The present combined optical, radio, and UV observations are of the irregular galaxy NGC 3448. It interacts with a smaller spiral companion, UGC 6016, forming the peculiar system Arp 205. Rotation curves were constructed from the red lines of a KPNO spectrum and from VLA H I observations. Abnormal velocity features were detected, and are attributed to clouds having at least 10 million solar masses. These clouds do not take part in the mean rotation, and one of them probably causes the observed obscuration on the NE side of the galaxy. They are probably similar to the high-velocity clouds detected in the Magellanic Stream and to the H I satellites found in nearby groups of spirals. The fact that all the clouds of the pair lie in the equatorial plane of the system could result from the interaction with the companion. An IUE spectrum reveals the presence of a hot nuclear component (25,000 K) with a total flux greater than the visible one, a characteristic of late-type galaxies.