2006/04/29 by N. Roche, Nathan Roche, Roche, Nathan
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0605015
12 pages, 11 figures
arxiv created 2006/04/29 · openalex publication_date 2006/04/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We perform UBR imaging and optical spectroscopy of the interacting galaxy pair Arp 104, at z=0.0098. This consists of NGC5218, a disturbed Sb barred spiral with an inclined outer shell, the round spheroidal NGC5216, a connecting bridge of length 50 kpc and a curved plume. Neither galaxy shows emission lines. NGC5218 has strong Balmer lines and appears to have undergone a major starburst some 0.2 Gyr ago, triggered by the last close passage of the two galaxies. The galaxy is very red in its centre, suggesting it is dusty, but its outer regions, and the bridge connecting the two galaxies, have the blue colours of 0.2-0.4 Gyr old stars. NGC5216 lacks strong Balmer lines but outside its centre is blue in U-B, suggesting it experienced a star-formation episode only about 40 Myr ago. This could have been fuelled by gas from NGC5218, transfered through the bridge. The bridge passes through NGC5216 to emerge as a plume extending 14 kpc to the SW. The plume, from its colours, is very young and may be a site of ongoing star-formation or the formation of a tidal dwarf galaxy.