The Andromeda (M31) galaxy displays several substructures in its inner halo whose origin as remnants of accreted satellites or perturbations the pre-existing disc are encoded properties their stellar populations (SPs), leaving traces on deep [OIII] 5007 \AA planetary nebulae luminosity functions (PNLFs). By characterizing morphology PNLFs, we constrain origin. From our 54 sq. deg. narrow-band s...

We report the discovery of significant stellar substructure in the halo and outer disk of our nearest large galactic neighbour, M31. Our deep panoramic survey with the Isaac Newton Telescope Wide Field Camera currently maps out an area of ≈ 25 ⊓⊔ around M31, extending along the semi-major axis to 55 kpc, and is the first to allow an uninterrupted study of the density and color distribution of i...

We present a comprehensive study of star-forming (SF) regions in the nearest large spiral galaxy M31. We use GALEX far-UV (1344-1786 Å, FUV) and near-UV (1771-2831 Å, NUV) imaging to detect young massive stars and trace the recent star formation across the galaxy. The FUV and NUV flux measurements of the SF regions, combined with ground-based data for estimating the reddening by interstellar du...

Aims. The purpose of this study is to explore the population of X-ray point sources in the bulge of M31, with the primary goal to contrast properties of various subpopulations, such as persistent and transient sources, primordial LMXBs and dynamically formed ones. Methods. Based on the data from 26 archival Chandra observations we study the source content and properties of various subpopu-latio...

Lying at a projected distance of 40 or 9 kpc from the centre of M31, Andromeda IV is an enigmatic object first discovered during van den Bergh’s search for dwarf spheroidal companions to M31. Being bluer, more compact and higher surface brightness than other known dwarf spheroidals, it has been suggested that And IV is either a relatively old ‘star cloud’ in the outer disk of M31 or a backgroun...

We present a multiwavelength investigation of the circumnuclear environment of the Andromeda Galaxy (M31), utilizing archival Chandra, FUSE, GALEX, HST and Spitzer data as well as ground-based observations. Based on the Chandra/ACIS data, we tightly constrain the X-ray luminosity of M31, the central supermassive black hole (SMBH) of the galaxy, to be L0.3−7 keV . 1.2 × 10 36 ergs s−1, approxima...

Progression through meiotic prophase is associated with dramatic changes in chromosome condensation. Two proteins that have been implicated in effecting these changes are the mammalian HP1-like protein M31 (HP1beta or MOD1) and the unusual core histone macroH2A1.2. Previous analyses of M31 and macroH2A1.2 localisation in mouse testis sections have indicated that both proteins are components of ...

The triple nucleus of M31 consists of a population of old red stars in an eccentric disk (P1 and P2) and another population of younger A stars in a circular disk (P3) around M31’s central supermassive black hole (SMBH). We argue that P1 and P2 determine the maximal radial extent of the younger A star population and provide the gas that fueled the starburst that generated P3. The eccentric stell...

Absolute and differential chemical abundances are presented for the largest group of massive stars in M31 studied to date. These results were derived from intermediate resolution spectra of seven B-type supergiants, lying within four OB associations covering a galactocentric distance of 5−12 kpc. The results are mainly based on an LTE analysis, and we additionally present a full non-LTE, unifie...

Recent studies of M31, the Galactic Centre (GC), and galaxy clusters have made tentative detections of an X-ray line at ∼3.5 keV that could be produced by decaying dark matter. We use high-resolution simulations of the Aquarius project to predict the likely amplitude of the X-ray decay flux observed in the GC relative to that observed in M31, and also of the GC relative to other parts of the Mi...