Related papers: Non-circular Motions in the Outer Perseus Spiral A…
In spite of much work, the overall spiral structure morphology of the Milky Way remains somewhat uncertain. In the last two decades, accurate distance measurements have provided us with an opportunity to solve this issue. Using the precise…
Combining HI data from the Canadian Galactic Plane Survey~(CGPS) and CO data from the Milky Way Imaging Scroll Painting (MWISP) project, we have identified a new segment of a spiral arm between Galactocentric radii of 15 and 19~kpc that…
The relation is studied between occurrence of a regular chain of star complexes and superclouds in a spiral arm, and other properties of the latter. A regular string of star complexes is located in the north-western arm of M31; they have…
The spiral arm tangencies are ideal lines of sight in which to determine the distribution of interstellar gas components in the spiral arms and study the influence of spiral density waves on the interarm gas in the Milky Way. We present a…
Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active…
We have conducted the first parallax and proper motion measurements of 6.7 GHz methanol maser emission using the Australian Long Baseline Array (LBA). The parallax of G339.884$-$1.259 measured from five epochs of observations is 0.48$\pm…
Integral field spectroscopy of the inner region of the Galactic Center, over a field of roughly 40"x40" was obtained at 2.06 microns (He I) and 2.16 microns (Brackett-gamma) using BEAR, an imaging Fourier Transform Spectrometer, at spectral…
We propose a new, more realistic, description of the perturbed gravitational potential of spiral galaxies, with spiral arms having Gaussian-shaped groove profiles. We investigate the stable stellar orbits in galactic disks, using the new…
We present the first internal motion measurement of the 6.7-GHz methanol maser within S269, a small HII region in the outer Galaxy, which was carried out in 2006 and 2011 using the Japanese VLBI Network (JVN). Several maser groups and weak…
Deep HI observations of the outer parts of disc galaxies demonstrate the frequent presence of extended, well-developed spiral arms far beyond the optical radius. To understand the nature and the origin of such outer spiral structure, we…
Spiral galaxies are ubiquitous in the local Universe. However the properties of spiral arms in them are still not well studied, and there is even less information concerning spiral structure in distant galaxies. We aim to measure the most…
In the inner 3kpc of M51 we find that logarithmic spirals provide good fits to the peak intensities in molecular gas observed by BIMA in the CO (J=1-0) emission line along the spiral arms. However, we measure significant asymmetries between…
Using 3D global hydro simulations coupled with radiative transfer calculations, we study the appearance of density waves induced by giant planets in direct imaging observations at near infrared wavelengths. We find that a 6 MJ planet in a…
We investigate the effect of spiral structure on the Galactic disk as viewed by pencil beams centered on the Sun, relevant to upcoming surveys such as ARGOS, SEGUE, and GAIA. We create synthetic Galactic maps which we call Pencil Beam Maps…
The mean Galactocentric radial velocities $\langle v_{R}\rangle(R,\varphi)$ of luminous red giant stars within the mid-plane of the Milky Way reveal a spiral signature, which could plausibly reflect the response to a non-axisymmetric…
We present new Faraday rotation measures (RMs) for 148 extragalactic radio sources behind the southern Galactic plane (253o < l < 356o, |b| < 1.5o), and use these data in combination with published data to probe the large-scale structure of…
We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two…
We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars…
We have determined 194 Faraday rotation measures (RMs) of polarized extragalactic radio sources using new, multi-channel polarization observations at frequencies around 1.4 GHz from the Very Large Array (VLA) in the Galactic plane at…
We present radio continuum observations of the spiral-shaped ionized feature (Sgr A West) within the inner pc of the Galactic center at three epochs spanning 1986 to 1995. The VLA A-configuration was used at $\lambda$2cm (resolution of…