Ortwin Gerhard

TL;DR: In this article, the authors present simulations of bar-unstable stellar discs in which the bars thicken into box/peanut shapes, revealing three different mechanisms for thickening the bars: buckling instability, vertical excitation of bar orbits by passage through the 2:1 vertical resonance, and a gradually increasing fraction of bar orbit trapped into this resonance.

TL;DR: In this paper, the authors measured the line-of-sight velocities and [O III] 5007 A expansion velocity for 11 planetary nebulae (PNs) in the Virgo Cluster core, at 15 Mpc distance, with the FLAMES spectrograph on the ESO VLT.

TL;DR: In this paper, a photometric survey of PNe in the galaxy's extended halo to characterise its PN population, as well as the surrounding intragroup light (IGL) of the Subcluster B is presented.

TL;DR: In this article, the imprint left by the Milky Way bar and spiral arms on the stars with full phase-space data in Gaia Data Release 2.0 was revealed. But the authors did not use a specific tracer to enhance the signatures left by these asymmetries.

TL;DR: In this article, the authors investigate the kinematics in the outer halo of M49, look for substructures, and describe the transition to the surrounding intra-group light.