相关论文: The Spatially-Resolved Star Formation History of t…

The outer regions of disc galaxies are becoming increasingly recognized as key testing sites for models of disc assembly and evolution. Important issues are the epoch at which the bulk of the stars in these regions formed and how discs grow…

We present a detailed analysis of two fields located 26 kpc (~5 scalelengths) from the centre of M31. One field samples the major axis populations--the Outer Disc field--while the other is offset by ~18' and samples the Warp in the stellar…

We explore the assembly history of the M31 bulge within a projected major-axis radius of 180" (~680 pc) by studying its stellar populations in Hubble Space Telescope WFC3 and ACS observations. Colors formed by comparing near-ultraviolet vs.…

We present resolved stellar photometry of 4 fields along the major axis of the M33 disk from images taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The photometry provides a detailed census of the red clump in…

Over the past several years, the Hubble Space Telescope (HST) has acquired many broad-band images of various regions in the M31 disk. I have obtained 27 such fields from the HST data archive in order to produce color-magnitude diagrams…

We map the star formation history across M31 by fitting stellar evolution models to color-magnitude diagrams of each 83$''{\times}$83$''$ (0.3$\times$1.4 kpc, deprojected) region of the PHAT survey outside of the innermost 6$'{\times}$12$'$…

The star formation history of the northern and southern M31 disk is measured using samples of BV photometry for 4' X 4' regions taken from the KPNO/CTIO Local Group Survey (Massey et al. 2001). The distances, mean reddening values, and age…

We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing $\sim$60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was…

While wide-field surveys of M31 have revealed much substructure at large radii, understanding the nature and origin of this material is not straightforward from morphology alone. Using deep HST/ACS data, we have derived further constraints…

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…

Studying the stellar populations in the outskirts of spiral galaxies can provide important constraints on their structure, formation, and evolution. To that end, we present VI photometry obtained with the Advanced Camera for Surveys for…

We examine the star-forming history (SFH) of the M31 disk during the past few hundred Myr. The luminosity functions (LFs) of main sequence stars at distances R_GC > 21 kpc (i.e. > 4 disk scale lengths) are matched by models that assume a…

We present the results on the star formation history and extinction in the disk of M82 over spatial scales of 10" (~180 pc). Multi-band photometric data covering from the far ultraviolet to the near infrared bands were fitted to a grid of…

Numerical simulations of galaxy formation within the cold dark matter (CDM) hierarchical clustering framework are unable to produce large disk galaxies without invoking some form of feedback to suppress gas cooling and collapse to a…

We continue the analysis of the dataset of our spectroscopic observation campaign of M31, by deriving simple stellar population properties (age metallicity and alpha-elements overabundance) from the measurement of Lick/IDS absorption line…

We present the first WFPC2 V, I photometry for the Sculptor Group galaxy NGC 300 in four fields ranging from the centre to the outer edge. We have made the first measurement of the star formation histories in two disk fields: the oldest…

We present a detailed analysis of the star formation history (SFH) of three fields in M33 located ~ 4 - 6 visual scale lengths from its nucleus. These fields were imaged with the Advanced Camera for Surveys on the Hubble Space Telescope and…

Images recorded with MegaCam are used to investigate the recent star-forming history (SFH) of the Local Group Sc galaxy M33. The properties of the stellar disk change near R = 8 kpc. Within this radius the star formation rate (SFR) has been…

We discuss H and K observations of three fields in the bulge and disk of M31 obtained with the Altair adaptive optics system and NIRI instrument on Gemini North. These are the highest resolution and deepest near-infrared observations…

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…