Related papers: NGC 6822 as a probe of dwarf galactic evolution
We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D=2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (IR) Keck Laser Guide Star…
Based on the archival Hubble Space Telescope images, we have performed stellar photometry for 18 dwarf galaxies. Branches of young and old stars are seen on the constructed Hertzsprung-Russell diagrams. Using the photometry of red giants…
To test the existence of a possible radial gradient in oxygen abundances within the Local Group dwarf irregular galaxy NGC 6822, we have obtained optical spectra of 19 nebulae with the EFOSC2 spectrograph on the 3.6-m telescope at ESO La…
The shape and diversity of dwarf galaxy rotation curves is at apparent odds with dark matter halos in a $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. We use mock data from isolated dwarf galaxy simulations to show that this owes to…
The dynamical evolution of the large (> 100 kpc), barred spiral galaxy NGC 6872 and its small companion IC 4970 in the southern group Pavo is investigated. We present N-body simulations with stars and gas and 21 cm HI observations carried…
We present HI 21cm and optical observations of UGC 3672 which is located near the centre of the nearby Lynx-Cancer void. We find that UGC 3672 consists of an approximately linearly aligned triplet of gas rich dwarfs with large scale…
We derive the stellar rotation curve of the Galaxy in the range of Galactocentric radii of R=4-16 kpc at different vertical heights from the Galactic plane of z between -2 and +2 kpc. We used the PPMXL survey, which contains the USNO-B1…
We present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, M_V=-2.9+/-0.8, r_h=19^{+8}_{-6} pc), recently discovered in the Pan-STARRS1 3{\pi} survey. The observations, conducted with DEIMOS on the…
We present results from an HST/ACS imaging study of the metal-poor blue compact dwarf galaxy SBS 1415+437. It has been argued previously that this is a very young galaxy that started to form stars only less than 100 Myr ago. However, we…
I provide a model rotation curve for the Milky Way that matches the details of the terminal velocity curve normalized to the Galactocentric distance $R_0 = 8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular…
We have observed the 13CO J=2-1, 12CO J=2-1 and 12CO J=3-2 lines at a few locations in the dwarf irregular galaxies IC 10 and NGC 6822 using the James Clerk Maxwell Telescope. In addition, we report the first detection of the 13CO J=3-2…
We report the results of a systematic photometric survey of the peripheral regions of a sample of fourteen globular clusters in the outer halo of the Milky Way at distances d_GC>25 kpc from the Galactic centre. The survey is aimed at…
The results of optical spectroscopy of two HII regions in UGCA 292 (CVn I dwA) are presented. UGCA 292 is a nearby (D=3.1 Mpc) gas-rich dwarf irregular galaxy (M_H/L_B ~ 6.9) which was first discovered in a blind HI survey. The derived…
A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies ($M_*=10^7$-$10^9$ M$_\odot$) are currently star-forming. However, recent observations of the large abundance of "Ultra-Diffuse…
We present new Keck/HIRES observations of six red giants in the globular cluster NGC 2419. Although the cluster is among the most distant and most luminous in the Milky Way, it was considered chemically ordinary until very recently. Our…
We present HST/WFPC2 single-star photometry for the blue dwarf galaxy UGCA 290, whose morphology is intermediate between classic iE Blue Compact Dwarfs and blue dwarfs which exhibit no red background sheet of older stars. The…
Optical red spectra of a set of 18 bright barred spiral galaxies are presented. The study is aimed at determining the local kinematics, and the physical conditions of ionized gas in the compact nucleus (inside a diameter of 5") and in the…
Abridged abstract: We present HI synthesis observations of the weak blue compact dwarf (BCD) galaxy NGC~2915. NGC~2915 has the HI properties of a late type spiral galaxy (Sd - Sm), including a double horn global profile, and HI spiral arms.…
Deep images obtained with MegaCam and WIRCam on the Canada-France-Hawaii Telescope are used to probe the stellar content outside of the central star-forming regions of M82. Stars evolving on the asymptotic giant branch (AGB) are traced…
The dwarf elliptical galaxy NGC 185- the closest early-type galaxy with detectable molecular gas- offers a unique opportunity for high angular resolution studies of the interstellar medium in early-type galaxies. I present interferometric…