Related papers: Tracing the Star Stream Through M31 Using Planetar…
Evidence for a bar at the center of the Milky Way triggered a renewed enthusiasm for dynamical modelling of the Galactic bar-bulge. Our goal is to compare the kinematics of a sample of tracers, planetary nebulae, widely distributed over the…
The chemo-dynamics of galaxy halos beyond the Local Group may now be mapped out through the use of globular clusters and planetary nebulae as bright tracer objects, along with deep multi-slit spectroscopy of the integrated stellar light. We…
We present 3D hydrodynamical simulations of a jet launched from the secondary star of a binary system inside a proto-planetary nebula. The secondary star moves around the primary in a close eccentric orbit. From the gasdynamic simulations…
To investigate the origins of S0 galaxies, we present a new method of analyzing their stellar kinematics from discrete tracers such as planetary nebulae. This method involves binning the data in the radial direction so as to extract the…
Tidal streams from existing and destroyed satellite galaxies populate the outer regions of the Andromeda galaxy (M31). This inhomogeneous debris can be studied without many of the obstacles that plague Milky Way research. We review the…
M31 has experienced a recent tumultuous merger history as evidenced from the many substructures that are still present in its inner halo, particularly the G1-Clump, NE- and W- shelves, and the Giant Stream (GS). We present planetary nebulae…
The interaction between an accreting satellite and the Andromeda galaxy (M31) has been studied analytically and numerically, using a high-resolution N-body simulation with $4\times10^7$ particles. For the first time, we show the…
Detailed studies of stellar populations in the halos of the Milky Way and the Andromeda (M 31) galaxies have shown increasing numbers of tidal streams and dwarf galaxies, attesting to a complicated and on-going process of hierarchical…
The galaxy pair NGC 5194/95 (M 51) is one of the closest and best known interacting systems. Despite its notoriety, however, many of its features are not well studied. Extending westward from NGC 5195 is a low surface brightness tidal tail,…
We present high-resolution, long-slit spectroscopic observations of two planetary nebulae with [WC] central stars located near the galactic bulge, M 1-32 and M 3-15. The observations were obtained with the 2.1-m telescope at the…
The Andromeda galaxy (M 31) has experienced a tumultuous merger history as evidenced by the many substructures present in its inner halo. We use planetary nebulae (PNe) as chemodynamic tracers to shed light on the recent merger history of M…
We report the discovery of a giant stellar tidal stream in the halo of NGC 4631, a nearby edge-on spiral galaxy interacting with the spiral NGC 4656, in deep images taken with a 40-cm aperture robotic telescope. The stream has two…
Planetary nebulae (PNe) are circumstellar gas ejected during an intense mass-losing phase in the the lives of asymptotic giant branch stars. PNe have a stunning variety of shapes, most of which are not spherically symmetric. The debate over…
Planetary Nebulae (PNe) are very important kinematical tracers of the outer regions of early-type galaxies, where the integrated light techniques fail. Under ad hoc assumptions, they allow measurements of rotation velocity and velocity…
The nearest giant spiral, M31, exhibits a kinematically hot stellar disc, a global star formation episode ~2-4 Gyr ago, and conspicuous substructures in its stellar halo that are suggestive of a recent accretion event. Recent chemodynamical…
This paper is a review of some of the recent modeling efforts to improve our understanding of structure formation and evolution of planetary nebulae including their interaction with the interstellar medium. New propositions have been made…
Recent spectroscopic observations of planetary nebulae (PNe) in several elliptical galaxies have revealed structural and kinematical properties of the outer stellar halo regions. In order to elucidate the origin of the properties of these…
We present a new modeling tool for planetary nebulae (PNe), based on 3D photoionization calculations. From models for two theoretical PNe, we show that the enhancement in the equatorial zone observed in several PNe is not necessarily due to…
We report the detection of a new satellite of M31, projected close to M32. And VIII is tidally distorted, with length ~10 kpc and width a few kpc. It contains 5-12 planetary nebulae (PNe) and 1-3 globular clusters, and has a velocity of…
We present evidence for a new Milky Way stellar tidal stream in the direction of the Andromeda and Triangulum (M31 and M33) galaxies. Using a matched-filter technique, we search the Sloan Digital Sky Survey Data Release 8 by creating…