相关论文: Hiding its age: the case for a younger bulge
We present accurate relative ages for a sample of 55 Galactic globular clusters. The ages have been obtained by measuring the difference between the horizontal branch and the turnoff in two, internally photometrically homogeneous databases.…
Recent discoveries have put the picture of stellar clusters being simple stellar populations into question. In particular, the color-magnitude diagrams of intermediate age (1-2 Gyr) massive clusters in the Large Magellanic Cloud (LMC) show…
We present a new database of our two-dimensional bulge-disk decompositions for 14,233 galaxies drawn from SDSS DR12 in order to examine the properties of bulges residing in the local universe ($0.005 < z < 0.05$). We performed…
Globular clusters trace the formation history of the spheroidal components of both our Galaxy and others, which represent the bulk of star formation over the history of the universe. They also exhibit a range of metallicities, with…
We calculate the contribution to Balmer line indices from far ultraviolet component sources. We find that this is significant, and may lead to identification of spurious age differences of the order of a total span of $\sim 6$ Gyrs or $\sim…
An overview is given of the results obtained about Galactic Structure studies towards the Galactic Centre from star counts. The results indicate the presence of an old, metal-rich population (Z=0.005-0.08; t=13-15 Gyr), presumably the old…
The color-magnitude diagram of $ \sim 3 \times 10^5 $ stars obtained for Baade's Window towards the Galactic bulge with the OGLE project reveals a surprisingly narrow main sequence due to galactic disk stars at a distance of $d \sim 2 $…
We report periods and JHKL observations for 648 oxygen-rich Mira variables found in two outer bulge fields at b=-7 degrees and l=+/-8 degrees and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys,…
We analyse the spatially resolved colours of distant galaxies of known redshift in the Hubble Deep Field, using a new technique based on matching resolved four-band internal colour data to the predictions of evolutionary synthesis models.…
A comparison is made between the age-metallicity relation obtained from four different types of studies: F and G stars in the Solar Neighbourhood, analysis of open clusters, galactic structure studies with the stellar population synthesis…
A chromospheric age distribution of 552 late-type dwarfs is transformed into a star formation history by the application of scale height corrections, stellar evolutionary corrections and volume corrections. We show that the disk of our…
We present a brief summary of our current results on the stellar distribution and population gradients of the resolved stars in the surroundings of ~50 nearby disk galaxies, observed with space- (Hubble & Spitzer) and ground-based…
We use data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey to study how the spatial variation in the stellar populations of galaxies relate to the formation of galaxies at $1.5 < z < 3.5$. We use the Internal Color…
Panchromatic spectral energy distribution (SED) from the ultraviolet (UV), optical to infrared (IR) photometry of NGC 628, combined with the evolutionary stellar population synthesis, is used to derive the spatially resolved age,…
We study the star-formation history of the Galactic bulge, as derived from the age distribution of the central stars of planetary nebulae that belong to this stellar population. The high resolution imaging and spectroscopic observations of…
Recent studies have shown that the observed main-sequence turn-off (MSTO) in colour-magnitude diagrams of intermediate age (1-2 Gyr) clusters in the LMC are broader than would be nominally expected for a simple stellar population. This has…
The structure and kinematics of the old component of the Galactic bulge are still a matter of debate. The bulk of the bulge as traced by red clump stars includes two main components, which are usually identified as the metal-rich and…
Galactic bulges are central to understanding galaxy formation and evolution. Here we report on recent studies using micro-lensing events to obtain spectra of high resolution and moderately high signal-to-noise ratios of dwarf stars in the…
A high number of embedded clusters is found in the Galaxy. Depending on the formation scenario, most of them can evolve to unbounded groups that are dissolved within a few tens of Myr. A systematic study of young stellar clusters showing…
We present the metallicity results from the ARGOS spectroscopic survey of the Galactic bulge. Our aim is to understand the formation of the Galactic bulge: did it form via mergers, as expected from Lambda CDM theory, or from disk…