Zobrazeno 1 - 10
of 1 411
pro vyhledávání: '"Frebel, A."'
Autor:
Roederer, Ian U., Beers, Timothy C., Hattori, Kohei, Placco, Vinicius M., Hansen, Terese T., Ezzeddine, Rana, Frebel, Anna, Holmbeck, Erika M., Sakari, Charli M.
We present stellar parameters and chemical abundances of 47 elements detected in the bright (V = 11.63) very metal-poor ([Fe/H] = -2.20 +- 0.12) star 2MASS J22132050-5137385. We observed this star using the Magellan Inamori Kyocera Echelle spectrogra
Externí odkaz:
http://arxiv.org/abs/2406.02691
Autor:
Andales, Hillary Diane, Figueiredo, Ananda Santos, Fienberg, Casey Gordon, Mardini, Mohammad K., Frebel, Anna
We present a detailed chemical abundance and kinematic analysis of six extremely metal-poor ($-4.2 \leq$ [Fe/H] $\leq-$2.9) halo stars with very low neutron-capture abundances ([Sr/H] and [Ba/H]) based on high-resolution Magellan/MIKE spectra. Three
Externí odkaz:
http://arxiv.org/abs/2405.07856
Neutron star mergers (NSMs) produce copious amounts of heavy r-process elements after a time delayed inspiral process. Once NSMs are present in a galaxy, r-process elements, such as Eu, are expected to significantly increase with time. Yet, there has
Externí odkaz:
http://arxiv.org/abs/2404.10067
Autor:
Burdge, Kevin B., El-Badry, Kareem, Kara, Erin, Canizares, Claude, Chakrabarty, Deepto, Frebel, Anna, Millholland, Sarah C., Rappaport, Saul, Simcoe, Rob, Vanderburg, Andrew
Evidence suggests that when compact objects such as black holes and neutron stars form, they may receive a ``natal kick,'' where the stellar remnant gains momentum. Observational evidence for neutron star kicks is substantial, yet limited for black h
Externí odkaz:
http://arxiv.org/abs/2404.03719
Autor:
Xylakis-Dornbusch, T., Hansen, T. T., Beers, T. C., Christlieb, N., Ezzeddine, R., Frebel, A., Holmbeck, E., Placco, V. M., Roederer, I. U., Sakari, C. M., Sneden, C.
Context. In recent years, the R-Process Alliance (RPA) has conducted a successful search for stars enhanced in elements produced by the rapid neutron-capture (r-)process. In particular, the RPA has uncovered a number of stars strongly enriched in lig
Externí odkaz:
http://arxiv.org/abs/2404.03379
Autor:
Ou, Xiaowei, Chiti, Anirudh, Shipp, Nora, Simon, Joshua D., Geha, Marla, Frebel, Anna, Mardini, Mohammad K., Erkal, Denis, Necib, Lina
The Hercules ultra-faint dwarf galaxy (UFD) has long been hypothesized to be tidally disrupting, yet no conclusive evidence has been found for tidal disruption owing partly to difficulties in identifying Hercules member stars. In this work, we presen
Externí odkaz:
http://arxiv.org/abs/2403.00921
We report on the discovery of the first ultra metal-poor (UMP) star 2MASS~J20500194$-$6613298 (J2050$-$6613; \mbox{[Fe/H] = $-4.05$}) selected from the Gaia BP/RP spectral catalog that belongs to the ancient Atari disk component. We obtained a high-r
Externí odkaz:
http://arxiv.org/abs/2402.07046
Autor:
Shah, Shivani P., Ezzeddine, Rana, Roederer, Ian U., Hansen, Terese T., Placco, Vinicius M., Beers, Timothy C., Frebel, Anna, Ji, Alexander P., Holmbeck, Erika, Marshall, Jennifer, Sakari, Charli M.
We present a detailed chemical-abundance analysis of a highly $r$-process enhanced (RPE) star, 2MASS J00512646-1053170, using high-resolution spectroscopic observations with $Hubble\ Space\ Telescope$/STIS in the UV and Magellan/MIKE in the optical.
Externí odkaz:
http://arxiv.org/abs/2401.12311
Autor:
Chiti, Anirudh, Mardini, Mohammad, Limberg, Guilherme, Frebel, Anna, Ji, Alexander P., Reggiani, Henrique, Ferguson, Peter, Andales, Hillary Diane, Brauer, Kaley, Li, Ting S., Simon, Joshua D.
The Large Magellanic Cloud (LMC) is the Milky Way's most massive satellite galaxy, which only recently (~2 billion years ago) fell into our Galaxy. Since stellar atmospheres preserve their natal cloud's composition, the LMC's recent infall makes its
Externí odkaz:
http://arxiv.org/abs/2401.11307
Autor:
Roederer, Ian U., Vassh, Nicole, Holmbeck, Erika M., Mumpower, Matthew R., Surman, Rebecca, Cowan, John J., Beers, Timothy C., Ezzeddine, Rana, Frebel, Anna, Hansen, Terese T., Placco, Vinicius M., Sakari, Charli M.
Publikováno v:
Science, 382, 1177-1180 (2023)
The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and
Externí odkaz:
http://arxiv.org/abs/2312.06844