Eva Manthey

Energy shift of first excited state in 10Be

Using the reaction 9Be(d,p)10Be (Q = 4.59 MeV) at Ed = 1.0 MeV, the energy of the first excited state in 10Be was found to be 3368.34±0.43 keV, in excellent agreement with the literature value. The result strengthens conclusions derived from recent studies of the cold ternary spontaneous fission of 252Cf.

The H(I) content of the advanced merger NGC4441

Context. NGC4441 is a candidate for a merger between a spiral and an elliptical galaxy (S+E merger), because it shows typical tidal structures such as an optical tail and two shells. With a far-infrared luminosity of similar to 5 x 10(9) L(circle dot) this galaxy belongs to the class of moderate luminosity mergers, in which the merging process induces (if at all) only a moderate starburst. Aims. The study of the atomic gas content allows us to investigate the merger history and the impact on the star formation. In particular, it is not clear from simulations whether an S+E merger leads to a gas concentration in the nucleus, resulting in a starburst, or whether the gas is spread out and therefore too diffuse for new star forming regions. Methods. We used the Westerbork Radio Synthesis Telescope to observe the properties of the Hi. By using this interferometer, we are able to study the large-scale Hi distribution and kinematics with high spatial and velocity resolution. Results. We found two Hi tails extending out to more than 40 kpc. In a central disc, the gas shows a fairly regular rotation pattern indicating that the gas started to settle after the merger. The total Hi mass adds up to 1.5 x 10(9) M(circle dot). By comparing the high resolution Hi maps with deep optical images, differences between the stellar and gaseous tidal features are apparent, which indicates an S+E merger origin.

A Multi Wavelength Study of Moderate Luminosity Mergers

Interaction and merging are the two most important driving forces of galaxy evolution. In recent years, much research activity has been focused on ULIRGs, which are the result of a disk‐disk merger, since they are among the most spectacular objects in the universe. However, ULIRGs are rare objects in the local universe. Thus, a study of a sample of merging galaxies of moderate FIR luminosity (∼ 1010 – 1011L⊙) may teach us as much as or even more about galaxy formation and evolution as investigations of the most extreme objects. Mergers having a moderate FIR luminosity can also be produced by merging two gas‐rich galaxies with unequal mass or a spiral and an elliptical (S+E). Alternatively, they can be a result of a faded major merger. As a class, moderate luminosity mergers are poorly studied and their role in the overall process of galaxy evolution is not yet well understood. We have obtained multicolour optical and NIR imaging data, optical spectroscopy, HI and CO (i.e. molecular gas) data for a large p...

Properties of moderate luminosity mergers

Interaction and merging are the two most important driving forces of galaxy evolution. In recent years, much research activity has been focused on ULIRGs, which are the result of a disk-disk merger, since are among the most spectacular objects in the universe. However, ULIRGs are rare objects in the local uni verse. Thus, a study of a sample of merging galaxies of moderate FIR luminosity (~ 10 10 L§) may teach us as much as or even more about galaxy formation and evolution than investigations of the most extreme objects. Mergers having a moderate FIR luminosity can also be produced by merging two gas-rich galaxies with unequal mass or a spiral and an elliptical (S+E). Alternatively, they can be a result of a faded major merger. As a class, moderate luminosity mergers are poorly studied and their role in the overall process of galaxy evolution is not yet well understood. We have obtained multicolour optical and NIR imaging data, optical spectroscopy, ill and CO (i.e.\ molecular gas) data for a large part of a sample of moderate luminosity merger candidates. A cross section of the results will be presented, and some preliminary conclusions will be drawn. These include an assessment of the crucial question of the extent (and existence) of the starburst resulting from the merger a dominating young stellar population and significant dust obscuration is indeed suggested for most of the sample galaxies.