Spiral Galaxies (6) ...

Some barred spiral galaxies exhibit strong star formation in the central region that appears to be associated with the influence of the bar on the gas and dust near the center.
Example: NGC 1365 in Visible Light
The figure below shows closeup visible (outlined in blue) and infrared (outlined in red) views of the center of the SBb barred spiral NGC 1365.

The small blue and red inset boxes in the center image indicate the regions displayed in the Hubble Space Telescope visible and IR views, respectively. The high-resolution visible image on the left shows the hub of the barred spiral. The core, in bright yellow, is surrounded by dark gas and dust being funneled into the central region by the rotation of the bar. The blue regions are young star clusters presumably forming in response to this flow of gas and dust.

Example: NGC 1365 in Infrared
The IR image of the central region shown on the right further clarifies the star formation taking place in the bar region of the spiral. The bright central spot is the core. The bright blue dots are young star clusters, the bright red dots are young star clusters still surrounded by gas and dust that are visible only in the IR image, and the fainter red dots are older star clusters, many of which are also seen in the visible image. Click on the "Identify" button to identify some corresponding points in the visible and IR views.

Example: NGC 4314
The left image is of the central region of the barred spiral NGC 4314, which is about 40 million light years away in the constellation Coma Berenices. The small inset in the upper left is a McDonald Observatory image of the galaxy. The tiny red box in the inset is the region shown in the full Hubble Space Telescope image.

The central region of the galaxy looks itself like a miniature spiral galaxy only about a thousand light years in diameter, with spiral arms and dust lanes and vigorous star formation. The stars being formed in the bright ring are less than 5 million years old, which is considerably younger than stars in the arms seen outside the bright ring of star birth. The color image is a superposition of UV, blue, IR, and H-alpha images; the purple color in the ring is hydrogen ionized by hot young stars.