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ABRIDGED) We revise the formation of Galactic GCs by adding the detailed chemical composition of their different stellar generations (from 1200 giants in 19 GCs) to their global parameters. We propose to identify as GCs those showing the…

The formation of massive stellar clusters in turbulent molecular clouds is investigated. We include artificial star formation and energy feedback of newly born stars. The obtained systems are not likely to survive. Case studies to determine…

Astrophysics · Physics 2007-05-23 Michael P. Geyer , Andreas Burkert

Many scenarios for the origin of the chemical anomalies observed in globular clusters (GCs; i.e., multiple populations) require that GCs were much more massive at birth, up to $10-100\times$, than they are presently. This is invoked in…

Astrophysics of Galaxies · Physics 2015-08-19 Nate Bastian , Carmela Lardo

Globular clusters (GCs) are among the oldest and densest stellar systems in the Universe, yet how they form remains a mystery. Here we present a suite of cosmological simulations in which both dark-matter-free GCs and dark-matter-rich dwarf…

Galaxy clusters are known to be reservoirs of Cosmic Rays (CRs), as inferred from theoretical calculations or detection of CR-derived observables. CR acceleration in clusters is mostly attributed to the dynamical activity that produces…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-05 Reju Sam John , Surajit Paul , Luigi Iapichino , Karl Mannheim , Harish Kumar

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) and with…

Many Galactic globular clusters (GCs) originated in diverse host galaxies before being subsequently incorporated into the Milky Way through hierarchical galaxy assembly. Identifying their origins is crucial for revealing galaxy properties…

Star clusters are formed in molecular clouds which are believed to be the birth places of most stars. From recent observational data, Lada & Lada(2003) estimated that only 4 to 7% of the proto-clusters have survived. Many factors could…

Astrophysics · Physics 2007-05-23 Hui-Chen Chen , Chung-Ming Ko

A systematic study on the long-term periodicities of known Galactic cataclysmic variables (CVs) was conducted. Among 1580 known CVs, 344 sources were matched and extracted from the Palomar Transient Factory (PTF) data repository. The PTF…

We created artificial color-magnitude diagrams of Monte Carlo dynamical models of globular clusters, and then used observational methods to determine the number of blue stragglers in those clusters. We compared these blue stragglers to…

Solar and Stellar Astrophysics · Physics 2015-06-15 Alison Sills , Evert Glebbeek , Sourav Chatterjee , Frederic A. Rasio

We present a novel approach to the riddle of star cluster multiple populations. Stars form from molecular cores. But not all cores form stars. Following their initial compression, such 'failed' cores re-expand, rather than collapsing. We…

Astrophysics of Galaxies · Physics 2022-01-19 G. Parmentier , A. Pasquali

Based on new CCD photometry and spectroscopy we confirm the presence of two cataclysmic variables (CVs) in the very old open cluster NGC 6791. One of these variables, known as B8, was observed by Rucinski, Kaluzny & Hilditch (1996) to…

Astrophysics · Physics 2009-10-30 J. Kaluzny , K. Z. Stanek , P. M. Garnavich , P. Challis

Using selection criteria based on amplitude, time and color, we have identified 329 objects as known or candidate cataclysmic variable (CVs) during the first year of testing and operation of the Zwicky Transient Facility (ZTF). Of these, 90…

Stars generally form faster than the ambipolar diffusion time, suggesting that several processes short circuit the delay and promote a rapid collapse. These processes are considered here, including turbulence compression in the outer parts…

Astrophysics · Physics 2009-11-13 Bruce G. Elmegreen

We critically examine the basic paradigm for the origin of the 2-3 hr period gap in cataclysmic variables (CVs). We carry out an extensive population synthesis study of CVs starting from ~ 3 x 10^6 primordial binaries, and evolving some ~ 2…

Astrophysics · Physics 2011-05-05 Steve B. Howell , Lorne A. Nelson , Saul Rappaport

Typical globular clusters (GCs - young and old) host stellar populations with little or no star-to-star variations in heavy elements (e.g., Ca, Fe) nor in age. Nuclear star clusters (NSCs), on the other hand, host complex stellar…

Astrophysics of Galaxies · Physics 2021-11-03 Nate Bastian , Joel Pfeffer

The mass distribution and chemical composition of globular cluster (GC) systems preserve fossil record of the early stages of galaxy formation. The observed distribution of GC colors within massive early-type galaxies in the ACS Virgo…

Astrophysics of Galaxies · Physics 2015-06-19 Hui Li , Oleg Y. Gnedin

In this paper, the second of a series, we study the stellar dynamical and evolutionary processes leading to the formation of compact binaries containing neutron stars (NSs) in dense globular clusters (GCs). For this study, 70 dense clusters…

Astrophysics · Physics 2009-11-13 N. Ivanova , C. Heinke , F. A. Rasio , K. Belczynski , J. Fregeau

We estimate the stochastic gravitational-wave background arising from all stellar core-collapse events in the universe based on the gravitational-wave signal predictions of recent numerical simulations. We focus on waveforms from slowly or…

General Relativity and Quantum Cosmology · Physics 2022-03-30 Bella Finkel , Haakon Andresen , Vuk Mandic

Bursty star formation in dwarf galaxies can slowly transform a steep dark matter cusp into a constant density core. We explore the possibility that globular clusters (GCs) retain a dynamical memory of this transformation. To test this, we…

Astrophysics of Galaxies · Physics 2019-09-11 M. D. A. Orkney , J. I. Read , James A. Petts , Mark Gieles