Hubble Space Telescope observations of globular cluster systems along the Hubble sequence of spiral galaxies

摘要: We have studied the globular cluster systems of seven giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers types Sa to Sc, allowing us study variation properties along sequence. photometry reaches ∼1.5 mag beyond turn-over magnitude luminosity function for each galaxy. Specific frequencies clusters (SN values) were evaluated by comparing numbers found our WFPC2 pointings with those Milky Way that would be detected same spatial region if placed at distance target galaxies. Results from this method consistent more commonly used constructing radial distribution functions clusters. SN values spirals B/T≲ 0.3 (i.e. a type later than about Sb) are value SN= 0.55 ± 0.25. suggest population represents ‘universal’, old halo is present around Most scenario which made up (i) aforementioned plus (ii) associated bulges, grows approximately linearly mass bulge. Such scenarios include ‘merger scenario’ formation elliptical as well ‘multi-phase collapse’ scenario, but it seems inconsistent ‘secular evolution’ Pfenniger & Norman, bulges formed disc stars means redistribution angular momentum through bar instabilities and/or minor perturbations. However, there one bulge-dominated (NGC 7814) low latest-type spirals. This can still viable some Thus, results histories early-type significantly different another.