Related papers: M31's Heavy Element Distribution and Outer Disk
We analyze the outer regions of M33, beyond 15 kpc in projected distance from its center using Subaru/HSC multi-color imaging. We identify Red Giant Branch (RGB) stars and Red Clump (RC) stars using the surface gravity sensitive $NB515$…
We present radial trends of metallicity ([Fe/H]) and abundance ratios ([X/Fe]) for several chemical elements -- including C, N, Na, and the so-called alpha-elements (O, Mg, Si, Ca, and Ti) -- in the bulge of M31, out to ~0.6kpc from the…
We present ultraviolet (UV) photometry of M31 globular clusters (GCs) found in 23 Galaxy Evolution Explorer (GALEX) images covering the entirety of M31. We detect 485 and 273 GCs (and GC candidates) in the near-ultraviolet (NUV; 2267 A) and…
The nature of the Sombrero galaxy (M 104 = NGC 4594) has remained elusive despite many observational studies at a variety of wavelengths. Here we present Hubble Space Telescope imaging of two fields at $\sim$16 and 33 kpc along the minor…
We present initial results from our JWST NIRSpec program to study the $\alpha$-abundances in the M31 disk. The Milky Way has two chemically-defined disks, the low-$\alpha$ and high-$\alpha$ disks, which are closely related to the thin and…
Several properties of the M31 disk, namely: opacity, extinction law and gas-to-dust ratio are studied by means of optical and near-infrared photometry of ten globular clusters and galaxies seen through the disk. The individual extinctions…
Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from…
Wide-field images obtained with the 3.6 meter Canada-France-Hawaii Telescope are used to investigate the spatial distribution and photometric properties of the brightest stars in the disk of M81 (NGC 3031). With the exception of the central…
Detailed studies of stellar populations in the halos of the Milky Way and the Andromeda (M 31) galaxies have shown increasing numbers of tidal streams and dwarf galaxies, attesting to a complicated and on-going process of hierarchical…
We present an updated catalog of 1300 objects in the field of M31, including 670 likely star clusters of various types. Archival images were inspected to confirm cluster classifications where possible, but most of the classifications were…
We present the largest and most detailed survey to date of the stellar populations in the outskirts of M31 based on the analysis of 14 deep HST/ACS pointings spanning the range 11.5-45.0 kpc. We conduct a quantitative comparison of the…
Theories of galaxy formation predict the existence of extended gas halo around spiral galaxies. If there are 10-100 nG magnetic fields at several ten kpc distances from the galaxies, extended galactic cosmic ray (CR) haloes could also…
We present internal velocity dispersions and precise radial velocities for 200 globular clusters (GCs) in M31 that are derived using new high-resolution spectra from MMT/Hectochelle. Of these, 163 also have King model structural parameters…
We present deep (V ~= 27) V- and I-band stellar photometry of G302 and G312, two globular star clusters in the halo of M31. These data were obtained using the Hubble Space Telescope's Wide Field/Planetary Camera 2. We find iron abundances…
We present analysis of nearly 1,000 near-infrared, integrated light spectra from APOGEE in the inner $\sim$7 kpc of M31. We utilize full spectrum fitting with A-LIST simple stellar population spectral templates that represent a population…
We study the age and metallicity distribution function (MDF) of metal-poor stars in the Milky Way halo as a function of galactocentric radius by combining N-body simulations and semi-analytical methods. We find that the oldest stars…
Gamma-ray haloes can exist around galaxies due to the interaction of escaping galactic cosmic rays with the surrounding gas. We have searched for such a halo around the nearby giant spiral Andromeda galaxy M31 using almost 7 years of Fermi…
We present the study of stellar populations in the central 5.5' (~1.2 kpc) of the M31 bulge by using the optical color magnitude diagram derived from HST ACS WFC/HRC observations. In order to enhance image quality and then obtain deeper…
We present the spectroscopic observations for 11 confirmed globular clusters of M31 with the OMR spectrograph on 2.16m telescope at Xinglong site of National Astronomical Observatories, Chinese Academy of Sciences. Nine of our sample…
In this paper we consider the implications of the distributions of dust and metals in the disc of M31. We derive mean radial dust distributions using a dust map created from Herschel images of M31 sampling the entire far-infrared (FIR)…