相关论文: A Pattern Speed in the Galaxy's OH/IR Stars
This paper examines the reliability of the Tremaine-Weinberg (TW) method in measuring the pattern speed of barred galaxies at high redshifts. Measuring pattern speeds at high redshift may help to shed light on the time evolution of…
Aims. New or refined methods for determining instantaneous scalar and vector pattern speeds from a restricted domain are developed, for applications in N-body simulations or in galaxies. Methods. The general feature used throughout follows…
We present surface photometry and stellar kinematics of NGC 2950, which is a nearby and undisturbed SB0 galaxy hosting two nested stellar bars. We use the Tremaine-Weinberg method to measure the pattern speed of the primary bar. This also…
When integrals in the standard Tremaine-Weinberg method are evaluated for the case of a realistic model of a doubly barred galaxy, their modifications introduced by the second rotating pattern are in accord with what can be derived from a…
The Tremaine-Weinberg equations are solved for a pattern speed that is allowed to vary with radius. The solution method transforms an integral equation for the pattern speed to a least squares problem with well established procedures for…
We study the kinematics of the barred spiral galaxy NGC 6946 by investigating the velocity field from H-alpha Fabry-Perot observations, determined the pattern speed of the bar by using the Tremaine-Weinberg method, and find a main pattern…
In spiral galaxies where the molecular phase dominates the ISM, the molecular gas as traced by CO emission will approximately obey the continuity equation on orbital timescales. The Tremaine-Weinberg method can then be used to determine the…
We have estimated the spiral pattern speed in the Galaxy $\Omega_p$ from a large sample of young open star clusters (OSCs). For this purpose, we have used 2494 OSCs younger than 50 Myr. Their mean proper motions, line-of-sight velocities,…
Previous work has related the Galactic bar to structure in the local stellar velocity distribution. Here we show that the bar also influences the spatial gradients of the velocity vector via the Oort constants. By numerical integration of…
We use the continuity equation to derive a method for measuring the pattern speed of the Milky Way's bar/bulge from proper motion data. The method has minimal assumptions but requires complete coverage of the non-axisymmetric component in…
Variable OH/IR stars are Asymptotic Giant Branch (AGB) stars with an optically thick circumstellar envelope that emit strong OH 1612 MHz emission. They are commonly observed throughout the Galaxy but also in the LMC and SMC. Hence, the…
I present a brief review of some of the most recent and active topics of star formation process in the Milky Way using mid and far infrared observations, and motivated by the research being carried out by our science group using data…
The circumstellar masers around evolved stars offer an interesting possibility to measure stellar parameters through VLBI astrometry. In this paper the application of this technique is discussed, including the accuracy and the uncertainties…
We report on our attempts to achieve a nearly steady-state gas flow in hydrodynamical simulations of doubly barred galaxies. After exploring the parameter space, we construct two models, for which we evaluate the photometric and the…
We observe the density wave angular pattern speed OMEGA-p to be near 12 to 17 km / s / kpc, by the separation between a typical optical HII region (from the spiral arm dust lane) and using a HII evolution time model to yield its relative…
An important dynamic parameter of barred galaxies is the bar pattern speed. Among several methods that are used for the determination of the pattern speed the Tremaine-Weinberg method has the advantage of model independency and accuracy. In…
We invoke the estimates of the amplitudes of the velocity perturbations $f_R$ and $f_\theta$ caused by the influence of a spiral density wave that have been obtained by us previously from three stellar samples. These include Galactic masers…
The pattern speed in one of the fundamental parameters that determines the structure of barred galaxies. This quantity is usually derived from indirect methods or by employing model assumptions. The number of bar pattern speeds derived…
Context: The Large Magellanic Cloud (LMC) internal kinematics have been studied in unprecedented depth thanks to the excellent quality of the Gaia mission data, revealing the disc's non-axisymmetric structure. Aims: We want to constrain the…
We are conducting a spectroscopic monitoring of O and WN -type stars in our Galaxy. In this work, we summarize some of our first results related to the search for radial-velocity variations indicative of orbital motion.