A5015331936- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Innovative Teaching Methods
- Natural Products and Applications
- Experimental Learning in Engineering
- Historical Astronomy and Related Studies
- Insurance, Mortality, Demography, Risk Management
- Astro and Planetary Science
- High-pressure geophysics and materials
- Space Exploration and Technology
- CCD and CMOS Imaging Sensors
- Educational Games and Gamification
- Historical and Architectural Studies
American University of Sharjah
2013-2023
Space Telescope Science Institute
2020-2022
Cadi Ayyad University
2018
University of Cincinnati
2011-2013
University of North Carolina at Chapel Hill
2013
The 'chromosome map' diagram (ChM) proved a successful tool to identify and characterize multiple populations (MPs) in 59 Galactic Globular Clusters (GCs). Here, we construct ChMs for 11 GCs of both Magellanic Clouds (MCs) with different ages compare MPs extra-Galactic environments, explore whether this phenomenon is universal through 'place' 'time'. are detected five clusters. fractions 1G stars, ranging from about 50% more than 80%, significantly higher those observed similar present-day...
Physics is like swimming; students cannot master it by watching, they have to practice. The challenge how motivate practice physics. Our approach was introduce Kahoot! in the classroom. Students solve problems on their own and use cellphones answer class. results show that liked this game motivated them more come prepared
The star formation (SFH) and chemical enrichment (CEH) histories of Local Group galaxies are traditionally studied by analyzing their resolved stellar populations in a form color-magnitude diagrams obtained with the Hubble Space Telescope. Star clusters can be integrated light using ground-based telescopes to much larger distances. They represent snapshots evolution host galaxy at different ages. Here we present simple theoretical framework for based on instantaneous recycling approximation...
The optical integrated spectra of three Large Magellanic Cloud young stellar clusters (NGC 1984, NGC 1994 and 2011) exhibit concave continua prominent molecular bands which deviate significantly from the predictions single population (SSP) models. In order to understand appearance these spectra, we create a set (MILES) models, make available community. We use archival International Ultraviolet Explorer UV independently constrain cluster masses extinction, rule out strong stochastic effects...
The utility of stellar cluster aging methods based on integrated spectra is clearly demonstrated by its extensive use researchers for decades. However, few studies have determined the accuracy such using a significant sample age-calibrated clusters with recent models. We amassed 27 clusters, 20 new we obtained SOAR and Blanco 4-m Telescopes, previously ages color-magnitude diagrams (CMDs). compared CMD to from clusters' spectra. find that in wavelength range 3626–6230 Å, when high resolution...
We use asad2, the new version of asad (Analyzer Spectra for Age Determination), to obtain age and reddening 27 Large Magellanic Cloud (LMC) clusters from full fitting integrated spectra using different statistical methods [χ2 Kolmogorov–Smirnov (KS) test] a set stellar population models including GALAXEV MILES. show that our results are in good agreement with colour–magnitude diagram (CMD) ages both models, metallicity does not affect determination spectrum method regardless model used log...
We present an investigation of 84 star clusters in the Large Magellanic Cloud (LMC) galaxy using different broad-band photometric, age-estimation methods. Because its intermediate distance, LMC is uniquely positioned to compare that have previously been aged both resolved photometry [colour–magnitude diagrams (CMDs)] constituent stars and unresolved methods (integrated, colour photometry). In our comparison between published CMD ages three similar, but based on UBV integrated colours, we...
ABSTRACT The presence of star-to-star light-element abundance variations (also known as multiple populations, MPs) appears to be ubiquitous within old and massive clusters in the Milky Way all studied nearby galaxies. Most previous studies have focused on resolved images or spectroscopy individual stars, although there has been significant effort past few years look for population signatures integrated light spectroscopy. If proven feasible, offer a potential way vastly open parameter space,...
Analyzer of Spectra for Age Determination (ASAD) is a new package that can easily predict the age and reddening stellar clusters from their observed optical integrated spectra by comparing them to synthesis model spectra. The ages obtained with ASAD are consistent previous cluster methods requiring more rigorous time-consuming analysis. This not only provides fast results, but also allows user comprehend accuracy these results providing surface plots spectral all combinations observations...
ABSTRACT Recent work has shown that the properties of multiple populations (MPs) within massive stellar clusters (i.e. in extent their abundance variations as well fraction stars show anomalous chemistry) depend on mass age host cluster. Such correlations are largely unexpected current models for formation MPs and hence provide essential insight into origin. Here, we extend our previous study presence or absence using integrated light spectroscopy ∼600 Myr, (∼107–108 M⊙) clusters, W3 W30,...
ABSTRACT We investigate the precision of ages and metallicities 21 000 mock simple stellar populations (SSPs) determined through full-spectrum fitting. The SSPs cover an age range 6.8 < log (age/yr) 10.2, for three wavelength ranges in optical regime, using both Padova MIST isochrone models. Random noise is added to model spectra achieve S/N ratios between 10 100 per pixel. find that ≥ 50, this technique can yield overall ∆log (age/yr)∼01 7.0 ≤ 8.3 8.9 9.4. For 9.5, which have...
We derive the first detailed chemical abundances of three star clusters in Large Magellanic Cloud (LMC), NGC1831 (436+/-22 Myr), NGC1856 (350+/-18 Myr) and [SL63]268 (1230+/-62 using integrated-light spectroscopic observations obtained with Magellan Echelle spectrograph on Baade telescope. [Fe/H], [Mg/Fe], [Ti/Fe], [Ca/Fe], [Ni/Fe], [Mn/Fe], [Cr/Fe] [Na/Fe] for clusters. Overall, our results match LMC literature as well those predicted by evolution models. For NGC1856, [Mg/Fe] ratios appear...
In this fourth paper of a series on the precision ages stellar populations obtained through full-spectrum fitting technique, we present first systematic analysis that compare age, metallicity and reddening star clusters from resolved unresolved data (namely colour-magnitude diagrams (CMDs) integrated-light spectroscopy) using same sets isochrones. We investigate results with both Padova isochrones MIST find there generally is good agreement between derived CMDs integrated spectra. However,...
In this second paper of a series on the accuracy and precision determination age metallicity simple stellar populations (SSPs) by means full spectrum fitting technique, we study influence star cluster mass through stochastic fluctuations number stars near top function, which dominate flux in certain wavelength regimes depending age. We consider SSP models based Padova isochrones, spanning range 7.0 $\leq$ log (age/yr) 10.1. Simulated spectra clusters $10^4 \leq M/M_{\odot} < 10^6$ are...
ABSTRACT In this third paper of a series on the precision obtaining ages stellar populations using full-spectrum fitting technique, we examine technique in deriving possible age spreads within star cluster. We test how well an internal spread can be resolved as function cluster age, population, mass fraction, and signal-to-noise ratio (S/N). For test, two (Age (SSP1) Age (SSP2)) are free parameters along with fraction SSP1. perform analysis 118 800 mock clusters covering all range 6.8...
Abstract Recent surveys uncovered new young massive clusters (YMCs) that host dozens of red supergiants (RSGs) in the inner Milky Way. These are ideal for studying most recent and violent star formation events Galaxy. However, due to high extinction affects Galactic plane, they need be studied through infrared (IR) spectroscopy. IR spectra RSGs have proven powerful tools obtaining chemical abundances. We present first [Fe/H] measurement (−0.07 ± 0.02) YMC VdBH 222 analysis its using Very...
We present the first application of novel approach based on data-driven machine learning methods applied to Multi-Unit Spectroscopic Explorer (MUSE) field data derive stellar abundances star clusters. MUSE has been used target more than 10,000 fields, and it is unique in its ability study dense fields such as clusters providing spectra for each individual star. use extragalactic young cluster NGC 1856, located Large Magellanic Cloud (LMC). [Fe/H] abundance 327 members addition [Mg/Fe],...
Abstract We present the first application of novel approach based on data-driven machine learning methods applied to Multi-Unit Spectroscopic Explorer (MUSE) field data derive stellar abundances star clusters. MUSE has been used target more than 10,000 fields, and it is unique in its ability study dense fields such as clusters providing spectra for each individual star. use extragalactic young cluster NGC 1856, located Large Magellanic Cloud (LMC). [Fe/H] abundance 327 members addition...
Abstract Recent surveys have uncovered new young massive clusters that host dozens of red supergiants (RSGs) near the inner Galaxy. However, many them still not been fully studied. Using Very Large Telescope/X-shooter near-infrared spectra, we present first radial velocity analysis for putative members candidate RSG cluster Alicante-8. Our results show a large dispersion velocities among member stars, indicating Alicante-8 does seem to be real cluster, unlike Alicante-7 and Alicante-10,...
In this paper we detect double-lined spectroscopic binaries (SB2) in five open clusters: NGC 2243, 2420, 3532, 6253 and 6705 (M 11) using a method based on high values of the projected rotational velocity when they are fitted with single star spectral model. Observed spectra were obtained from ESO archive. The was validated sets synthetic for binary stars. It is able to reliably select without confusing them stars, if components rotate slowly radial separation sufficiently high. We found 60...
ABSTRACT In this paper we detect double-lined spectroscopic binaries (SB2) in five open clusters: NGC 2243, 2420, 3532, 6253, and 6705 (M 11) using a method based on high values of the projected rotational velocity when they are fitted with single star spectral model. Observed spectra were obtained from European Southern Observatory archive. The was validated sets synthetic for binary stars. It is able to reliably select without confusing them stars, if components rotate slowly radial...