The projected structures and integrated properties of the Andromeda I, II, III, V, VI, VII and Cetus dwarf spheroidal galaxies are analysed based upon resolved counts of red giant branch stars. The observations were taken as part of the Isaac Newton Telescope Wide Field Survey of M31 and its environs. For each object, we have derived isopleth maps, surface brightness profiles, intensity-weighte...

We present the latest results from our project to search for new planetary nebulae in nearby galaxies using Sloan Digital Sky Survey (SDSS) imaging data. Our method is based on photometric criteria and can be applied to galaxies where PNe appear as point sources. We applied these criteria to the whole area of M31 as scanned by SDSS, detecting 130 new PN candidates and 30 known PNe. All selected...

This article reviews the nature and distribution of baryonic dark matter in galaxies , with a particular emphasis on the Milky Way. The microlensing experiments towards the Large Magellanic Clouds, the Andromeda Galaxy and the bulge provide evidence on the characteristic mass and abundance of baryonic dark matter, as do direct searches for local counterparts of dark halo populations.

The last few months have seen the measurements of the radial velocities of all of the dwarf spheroidal companions to the Andromeda galaxy (M31) using the spectrographs (HIRES and LRIS) on the Keck Telescope. This paper summarises the data on the radial velocities and distances for all the companion galaxies and presents new dynamical modelling to estimate the mass of extended halo of M31. The b...

We present BIMA observations of a 20 field in the northeastern spiral arm of M31. In this region we find six giant molecular clouds (GMCs) that have a mean diameter of 57 13 pc, a mean velocity width of 6:5 1:2 km s , and a mean molecular mass of 3:0 1:6 ð Þ ; 10 M . The peak brightness temperature of these clouds ranges from 1.6 to 4.2 K. We compare these clouds to clouds in M33 observed by Wi...

We present a color-magnitude diagram (CMD) of the globular cluster SKHB-312 in the Andromeda galaxy (M31), obtained with the Advanced Camera for Surveys on the Hubble Space Telescope. The cluster was included in deep observations taken to measure the star formation history of the M31 halo. Overcoming a very crowded field, our photometry of SKHB-312 reaches mV ≈ 30.5 mag, more than 1 mag below t...

Using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope, we have obtained deep optical images reaching stars well below the oldest main sequence turnoff in three fields of the Andromeda Galaxy: the spheroid, tidal stream, and outer disk. These observations allow a complete reconstruction of the star formation history in these fields. We analyze the color-magnitude diagrams of ...

It was found that satellites of nearby galaxies can form flattened co-rotating structures called disks or planes satellites. Their existence is not expected by the current galaxy formation simulations in standard dark matter-based cosmology. On contrary, modified gravity offers a promising alternative: objects are tidal dwarf galaxies, is, small from tails interacting galaxies. After introducin...

We present a color-magnitude diagram (CMD) for a minor-axis field in the halo of the Andromeda galaxy (M31), 51 arcmin (11 kpc) from the nucleus. These observations, taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope, are the deepest optical images yet obtained, attaining 50% completeness at mV = 30.7 mag. The CMD, constructed from ∼ 3× 105 stars, reaches more than 1...

Amajor uncertainty in the dynamical history of the local group of galaxies originates from the unknown transverse speed of the Andromeda galaxy (M31) relative to the Milky Way. We show that the recent VLBA measurement of the proper motion of Andromeda’s satellite, M33, severely constrains the possible values of M31’s proper motion. The condition that M33’s stellar disk will not be tidally disru...