Results 21 to 30 of about 24,585 (264)

Nucleosynthesis in Massive Population II Stars [PDF]

Symposium - International Astronomical Union, 1978
According to the conventional wisdom, the first stars formed in our Galaxy, including the massive ones responsible for most heavy element synthesis, must have had metal abundances much lower than solar. They may also have had somewhat lower helium abundances, corresponding to an enrichment ΔY/ΔZ = 2.7 ± 1.0 over the history of the Galaxy, a larger ...
David S. P. Dearborn, Virginia Trimble
openaire   +1 more source

The Impact of Patchy Reionization on Ultrafaint Dwarf Galaxies

The Astrophysical Journal, 2023
We investigate how patchy reionization affects the star formation history (SFH) and stellar metallicity of ultrafaint dwarf galaxies (UFDs). Patchy reionization refers to varying ultraviolet background strengths depending on a galaxy’s environment ...
Jaeeun Kim, Myoungwon Jeon, Yumi Choi, Hannah Richstein, Elena Sacchi, Nitya Kallivayalil   +5 more
doaj   +1 more source

Multiple Populations in Star Clusters

Universe, 2022
We review the multiple population (MP) phenomenon of globular clusters (GCs): i.e., the evidence that GCs typically host groups of stars with different elemental abundances and/or distinct sequences in photometric diagrams.
Antonino P. Milone, Anna F. Marino
doaj   +1 more source

[Fe/H]Ratios in Population II Stars [PDF]

Symposium - International Astronomical Union, 1991
Abundances of Population II stars of the field and globular cluster systems are reviewed. Emphasis is placed on [Fe/H] ratios determined from analyses of moderate- and high-resolution spectroscopic data. The status of analyses of metal-deficient stars is examined from the viewpoint of number of analyses and number of stars, overall distribution of the [
openaire   +1 more source

The Metallicity Variations Along the Chromosome Maps: The Globular Cluster 47 Tucanae

The Astrophysical Journal, 2023
The “chromosome maps” (ChMs) of globular clusters (GCs) have revealed that these ancient structures are inhomogeneous in metallicity in various ways and in different natures.
A. F. Marino, A. P. Milone, E. Dondoglio, A. Renzini, G. Cordoni, H. Jerjen, A. Karakas, E. P. Lagioia, M. V. Legnardi, M. McKenzie, A. Mohandasan, M. Tailo, D. Yong, T. Ziliotto   +13 more
doaj   +1 more source

Detailed Chemical Abundances of Stars in the Outskirts of the Tucana II Ultrafaint Dwarf Galaxy

The Astronomical Journal, 2023
We present chemical abundances and velocities of five stars between 0.3 and 1.1 kpc from the center of the Tucana II ultrafaint dwarf galaxy (UFD) from high-resolution Magellan/MIKE spectroscopy. We find that every star is deficient in metals (−3.6 < [Fe/
Anirudh Chiti, Anna Frebel, Alexander P. Ji, Mohammad K. Mardini, Xiaowei Ou, Joshua D. Simon, Helmut Jerjen, Dongwon Kim, John E. Norris   +8 more
doaj   +1 more source

Radial velocities of population II binary stars. I.

Astronomische Nachrichten, 2002
Here we publish the second list of radial velocities for 91 Hipparcos stars, mostly high transverse velocity binaries without previous radial velocity measurements. The measurements of radial velocities are done with a CORAVEL-type radial velocity spectrometer with an accuracy better than 1 km/s.
Bartkevicius, A., Sperauskas, J.
openaire   +2 more sources

Tracing ωCentauri’s origins: Spatial and chemical signatures of its formation history

Astronomy & Astrophysics
ωCentauri (ωCen), with its unmatched chemical complexity, is the most enigmatic Galactic globular cluster (GC). We combine photometric and spectroscopic catalogs to identify distinct stellar populations within ωCen, investigate their spatial distribution
Dondoglio E., Milone A. P., Marino A. F., Mastrobuono-Battisti A., Bortolan E., Legnardi M. V., Ziliotto T., Muratore F., Cordoni G., Lagioia E. P., Tailo M.   +10 more
doaj   +1 more source

Are Fertility Preservation Procedures Before Gonadotoxic Therapy and Hematopoietic Stem Cell Transplantation Feasible and Safe in Very Young Children? A Retrospective Cohort Study

Pediatric Blood &Cancer, EarlyView.
ABSTRACT Background Fertility preservation (FP) is increasingly integrated into the care of pediatric patients exposed to gonadotoxic therapy or conditioning for hematopoietic stem cell transplantation (HSCT), yet perioperative data in infants and toddlers remain scarce.
Kerstin Saalabian, Yannick Braun, Till‐Martin Theilen, Anke Barnbrock, Theresa Rohm, Fabienne Hammant, Nicole Sänger, Aynura Abbasova‐Semiz, Jan‐Henning Klusmann, Thomas Klingebiel, Udo Rolle, Peter Bader, Henning C. Fiegel, Andrea Jarisch   +13 more
wiley   +1 more source

Is there a Population II analogy to the F star lithium dip? [PDF]

Proceedings of the National Academy of Sciences, 1997
Observers have found a small number of lithium-depleted halo stars in the temperature range of the Spite plateau. The current status of the mass-loss hypothesis for producing the observed lithium dip in Population (Pop) I stars is briefly discussed and extended to Pop II stars as a possible explanation for these halo objects. Based
D S, Dearborn, D N, Schramm
openaire   +2 more sources