We present H I observations of the edge-on galaxy NGC 891. These are among the deepest ever performed on an external galaxy. They reveal a huge gaseous halo, much more extended than seen previously and containing almost 30% of the H I. This H I halo shows structures on various scales. On one side, there is a filament extending (in projection) up to 22 kpc vertically from the disk. Small (MHI ∼ ...

The identification and observation of planetary nebulae in the Andromeda galaxy (M3I) and its companions provide a powerful means of studying their old stellar populations. The direct determination of chemical abundances and radial velocities for even the brightest individual old stars is impossible at the distance of M31. The strongest emission lines of planetary nebulae are as bright as the e...

We define a large sample of galaxies for use in a study of the fundamental plane in the intermediate redshift cluster CL1358+62 at z = 0.33. We have analyzed high resolution spectra for 55 members of the cluster. The data were acquired with the Low Resolution Imaging Spectrograph on the Keck I 10m telescope. A new algorithm for measuring velocity dispersions is presented and used to measure the...

We present models for dusty high–redshift Lyα emitting galaxies by combining the Press–Schechter formalism with a treatment of inhomogeneous dust distribution inside galaxies. These models reproduce the surface density of emitters inferred from recent observations, and also agree with previous non–detections. Although a detailed determination of the individual model parameters is precluded by u...

In a dynamical model for the origin of the Magellanic Clouds and their large orbital angular momenta around the Galaxy, we consider that a primordial gas-rich Andromeda galaxy collided with our similar Galaxy in an oblique sense some 10 Gyr ago and it left the latter following the Hubble expansion law approximately. A huge gaseous halo was hydrodynamically compressed at their closest approach a...

Measuring the proper motions and geometric distances of galaxies within the Local Group is very important for our understanding of its history, present state and future. Currently, proper motion measurements using optical methods are limited only to the closest companions of the Milky Way. However, given that VLBI provides the best angular resolution in astronomy and phasereferencing techniques...

We present results based on an XMM-Newton observation of the prototype narrow-line Seyfert 1 galaxy I Zw 1 performed in June 2002. The 0.6−12 keV spectrum is well described by a steep power-law (Γ ∼ 2.3) and a weak soft blackbody component (kT ∼ 200 eV) below 2 keV. The soft X-ray excess emission is featureless and contributes only ∼ 10% to the total X-ray emission in the 0.6− 2 keV band. There...

Abstract Half of the satellite galaxies Andromeda form a narrow plane termed Great Plane (GPoA), and their line-of-sight velocities display correlation reminiscent rotating structure. Recently reported first proper-motion measurements for on-plane satellites NGC 147 185 indicate that they indeed co-orbit along GPoA. This provides novel opportunity to compare M31 system ΛCDM expectations. We per...

This paper presents [C I], 12CO J=4−3, and 12CO J=3−2 maps of the barred spiral galaxy M83 taken at the James Clerk Maxwell Telescope. Observations indicate a double peaked structure which is consistent with gas inflow along the bar collecting at the inner Lindblad resonance. This structure suggests that nuclear starbursts can occur even in galaxies where this inflow/collection occurs, in contr...