相关论文: Tango of Titans: Centaurus A and M83 as a Local Gr…

The Milky Way and Andromeda galaxy are each surrounded by a thin plane of satellite galaxies that may be corotating. Cosmological simulations predict that most satellite galaxy systems are close to isotropic with random motions, so those…

The galaxy system around NGC4490 was recently highlighted to display a flattened, kinematically correlated structure reminiscent of satellite galaxy planes around other hosts. Since known satellite planes are in tension with $\Lambda$CDM…

We combine the equations of motion that govern the dynamics of galaxies in the local volume with Bayesian techniques in order to fit orbits to published distances and velocities of galaxies within $\sim 3$ Mpc. We find a Local Group (LG)…

Current models of galaxy formation predict that galaxy pairs of comparable magnitudes should become increasingly rare with decreasing luminosity. This seems at odds with the relatively high frequency of pairings among dwarf galaxies in the…

We use the SDSS-Gaia catalogue to search for substructure in the stellar halo. The sample comprises 62\,133 halo stars with full phase space coordinates and extends out to heliocentric distances of $\sim 10$ kpc. As actions are conserved…

We find a deficiency of binary stars moving on strongly retrograde Galactic orbits. No binary deficiencies are seen for U or W velocities, however. From theoretical analyses, we rule out preferential disruption of pre-existing binary stars…

At a distance of about 3.8 Mpc, the radio galaxy Centaurus A is the closest active galaxy. Therefore it is a key target for studying the innermost regions of active galactic nuclei (AGN). VLBI observations conducted within the framework of…

The globular cluster Omega Centauri (NGC 5139) is the most massive and brightest cluster in our Galaxy. It has also a moderately high mass to light ratio (3.6) and an anomalous flattening (0.83) for a globular cluster. This cluster is also…

The Local Group (LG) consists of two giant spiral galaxies, the Milky Way (MW) and Andromeda (M31), and several smaller galaxies. The MW and M31 are approaching each other at a radial velocity of about $-109\,$km\,s$^{-1}$. Observational…

A projected mass estimator and a maximum likelihood estimator are developed to best determine the mass of stellar clusters from proper motion data. Both methods effectively account and correct for errors in the velocities, and provide an…

We present new mass estimates for Andromeda (M31) using the orbital angular momenta of four satellite galaxies (M33, NGC 185, NGC 147, IC 10) derived from existing proper motions, distances, and line-of-sight velocities. We infer two masses…

We combine new Lucky Imaging astrometry from NTT/AstraLux Sur with already published astrometry from the AstraLux Large M-dwarf Multiplicity Survey to compute orbital elements and individual masses of the 2MASS J10364483+1521394 triple…

Mergers of and interactions between galaxies imprint a wide diversity of morphological, dynamical, and chemical characteristics in stellar halos and tidal streams. Measuring these characteristics elucidates aspects of the progenitors of the…

The $\alpha$ Cen binary system is a well-known stellar system with very accurate observational constraints to structure of its component stars. In addition to the classical non-seismic constraints, there are also seismic constraints for the…

We successfully measured the trigonometric parallax of Sagittarius A* (Sgr A*) to be $117\pm17$ micro-arcseconds ($\mu$as) using the VLBI Exploration of Radio Astrometry (VERA) with the newly developed broad-band signal-processing system…

We calculate the most massive object in the Universe, finding it to be a cluster of galaxies with total mass M_200=3.8e15 Msun at z=0.22, with the 1 sigma marginalized regions being 3.3e15 Msun<M<4.4e15 Msun and 0.12<z<0.36. We restrict…

We study dwarf galaxies in the Centaurus A group to investigate their metallicity and possible environmental effects. The Centaurus A group (at ~4 Mpc from the Milky Way) contains about 50 known dwarf companions of different morphologies…

We use spectra observed with the integral-field spectrograph MUSE to reveal the central kinematics of the Galactic globular cluster Messier 80 (M80, NGC 6093). Using observations obtained with the recently commissioned narrow-field mode of…

Centaurus A (Cen A) is a bright radio source associated with the nearby galaxy NGC 5128 where high-resolution radio observations can probe the jet at scales of less than a light-day. The South Pole Telescope (SPT) and the Atacama Pathfinder…

We present the highest resolution --- 15 pc (0.03'') --- ALMA $^{12}$CO(2-1) line emission and 1.3mm continuum maps, tracers of the molecular gas and dust, respectively, in the nearby merging galaxy system NGC 6240, that hosts two…