We observed the nearby spiral galaxy M31 with the Long-Wavelength Spectrometer on board the Infrared Space Observatory. Far-infrared line-to-continuum ratios of [C ii]/100 μm ' 6 × 10−3 were obtained for the central kiloparsec region along the major axis of the galaxy. These ratios are 2–3 times higher than those in the Galactic counterpart and are closer to those in the general Galactic plane....

The origin of M32, the closest compact elliptical galaxy (cE), is a long-standing puzzle of galaxy formation in the Local Group. Our N-body/smoothed particle hydrodynamics simulations suggest a new scenario in which the strong tidal field of M31 can transform a spiral galaxy into a compact elliptical galaxy. As a low-luminosity spiral galaxy plunges into the central region of M31, most of the o...

We present a progress report of our wide field CCD survey of globular clusters in M31. We have covered 3 deg × 3 deg area centered on M31, using the KPNO 0.9m and Washington CMT1 filters. Our survey is much deeper and more sensitive than previous surveys. We have found several hundred new globular cluster candidates in M31 in addition to confirming previously known globular clusters, and also h...

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...

Mid-infrared observations of the Andromeda galaxy, M31, obtained with the Infrared Array Camera on board the Spitzer Space Telescope are presented. The image mosaics cover areas of approximately 3. • 7 × 1. • 6 and include the satellite galaxies M32 and NGC 205. The appearance of M31 varies dramatically in the different mid-infrared bands, from the smooth bulge and disk of the old stellar popul...

We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3-mag semi-detached system with components of late-O and early-B spectral types. From the light and radial velocity curves we have carried out an accurate determination of the masses and radii of the components. Their effective temperatures have been estimated ...

Mid-infrared observations of the Andromeda galaxy, M31, obtained with the Infrared Array Camera on board the Spitzer Space Telescope are presented. The image mosaics cover areas of approximately 3. • 7 × 1. • 6 and include the satellite galaxies M32 and NGC 205. The appearance of M31 varies dramatically in the different mid-infrared bands, from the smooth bulge and disk of the old stellar popul...

We determine the X-ray spectral properties of a sample of low-mass X-ray binaries (LMXBs) which reside in globular clusters of M31, as well as five LMXBs in Galactic globular clusters and in the Large Magellanic Cloud using the ROSAT PSPC. We find a trend in the X-ray properties of the LMXBs as a function of globular cluster metallicity. The spectra of LMXBs become progressively softer as the m...

A murine monoclonal antibody (M31-15) was identified using the penetration-inhibiting assay of a human lung adenocarcinoma cell line (MAC10) and remarkably inhibited the phagokinetic tract motility of various cancer cell lines. The antigen, motility-related protein (MRP-1), recognized by M31-15, was 25- and 28-kD proteins, and M31-15 was used to isolate a cDNA clone from a human breast carcinom...

We find that the globular cluster systems of the Milky Way and of our neighboring spiral galaxy, M31, comprise two distinct entities, differing in three respects. First, M31 has a set of young globular clusters (GCs), ranging in age from a few 100 Myr to 5 Gyr old, as well as old globular clusters. No such very young GCs are known in the Milky Way. Second, we confirm that the oldest M31 GCs hav...