Zobrazeno 1 - 10
of 112
pro vyhledávání: '"Frebel, A."'
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 521:2623-2648
We apply the clustering algorithm HDBSCAN on the Gaia early third data release astrometry combined with the Gaia second data release radial velocity measurements of almost 5.5 million stars to identify the local stellar kinematic substructures in the
Autor:
Mohammad K Mardini, Anna Frebel, Rana Ezzeddine, Anirudh Chiti, Yohai Meiron, Alexander P Ji, Vinicius M Placco, Ian U Roederer, Jorge Meléndez
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 517:3993-4004
We present a high-resolution (R ∼ 35 000), high signal-to-noise (S/N = 350) Magellan/MIKE spectrum of the bright extremely metal-poor star 2MASS J1808−5104. We find [Fe/H] = −4.01 (spectroscopic LTE stellar parameters), [Fe/H] = −3.8 (photome
Autor:
Mardini, Mohammad K., Frebel, Anna, Betre, Leyatt, Jacobson, Heather, Norris, John E., Christlieb, Norbert
Based on high-resolution spectra obtained with Magellan/MIKE, we present a chemo-dynamical analysis for 27 near main-sequence turnoff metal-poor stars, including 20 stars analyzed for the first time. The sample spans a range in [Fe/H] from -2.5 to -3
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d4c091d5306ae7ca843c386561ef462b
http://arxiv.org/abs/2305.05363
http://arxiv.org/abs/2305.05363
Context: Carbon Enhanced Metal-Poor (CEMP) stars ($\mathrm{[C/Fe]} > 0.7$) are known to exist in large numbers at low metallicity in the Milky Way halo and are important tracers of early Galactic chemical evolution. However, very few such stars have
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::527b53b796f782f61d1c03124b528b80
http://arxiv.org/abs/2305.02316
http://arxiv.org/abs/2305.02316
In this paper, we construct the circular velocity curve of the Milky Way out to $\sim 30$ kpc, providing an updated model of the dark matter density profile. We derive precise parallaxes for 120,309 stars with a data-driven model, using APOGEE DR17 s
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e2074779a4cbbbc78778960fefebdaac
http://arxiv.org/abs/2303.12838
http://arxiv.org/abs/2303.12838
We investigate the distribution of the lithium abundances, A(Li), of metal-poor dwarf and subgiant stars within the limits 5500 K < Teff < 6700 K, -6.0 < [Fe/H] < -1.5, and logg > ~3.5 (a superset of parameters first adopted by Spite and Spite), usin
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dac38c7e146e6e8084a1912457e407a4
http://arxiv.org/abs/2303.11497
http://arxiv.org/abs/2303.11497
Autor:
Frebel, Anna, Ji, Alexander P.
This chapter presents an overview of the recent progress on spectroscopic observations of metal-poor stars with r-process element signatures found in the Milky Way's stellar halo and satellite dwarf galaxies. Major empirical lessons related to the or
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::367e8639abd36c8deb323c9604fdb817
http://arxiv.org/abs/2302.09188
http://arxiv.org/abs/2302.09188
Autor:
Ian U. Roederer, John J. Cowan, Marco Pignatari, Timothy C. Beers, Elizabeth A. Den Hartog, Rana Ezzeddine, Anna Frebel, Terese T. Hansen, Erika M. Holmbeck, Matthew R. Mumpower, Vinicius M. Placco, Charli M. Sakari, Rebecca Surman, Nicole Vassh
We present new observational benchmarks of rapid neutron-capture process (r-process) nucleosynthesis for elements at and between the first (A ~ 80) and second (A ~ 130) peaks. Our analysis is based on archival ultraviolet and optical spectroscopy of
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d569ad7dd4a05bbad140851fb27f74d1
http://arxiv.org/abs/2210.15105
http://arxiv.org/abs/2210.15105
Autor:
Kowkabany, Jeremy, Ezzeddine, Rana, Charbonnel, Corinne, Roederer, Ian U., Li, Yangyang, Hackshaw, Zoe, Beers, Timothy C., Frebel, Anna, Hansen, Terese T., Holmbeck, Erika, Placco, Vinicius M., Sakari, Charli M.
We present the discovery of 2MASS J05241392-0336543 (hereafter J0524-0336), a very metal-poor ([Fe/H]=-2.43 \pm 0.16), highly r-process-enhanced ([Eu/Fe]=+1.34 \pm 0.10) Milky Way halo field red giant star, with an ultra high Li abundance of A(Li)(3D
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6f0ba9f83ef69f2fba33d42132a3f5fa
http://arxiv.org/abs/2209.02184
http://arxiv.org/abs/2209.02184
Autor:
Joshua D. Simon, Thomas M. Brown, Burçin Mutlu-Pakdil, Alexander P. Ji, Alex Drlica-Wagner, Roberto J. Avila, Clara E. Martínez-Vázquez, Ting S. Li, Eduardo Balbinot, Keith Bechtol, Anna Frebel, Marla Geha, Terese T. Hansen, David J. James, Andrew B. Pace, M. Aguena, O. Alves, F. Andrade-Oliveira, J. Annis, D. Bacon, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, P. Doel, S. Everett, I. Ferrero, J. Frieman, J. García-Bellido, M. Gatti, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, K. Kuehn, N. Kuropatkin, J. L. Marshall, J. Mena-Fernández, R. Miquel, A. Palmese, F. Paz-Chinchón, M. E. S. Pereira, A. Pieres, A. A. Plazas Malagón, M. Raveri, M. Rodriguez-Monroy, E. Sanchez, B. Santiago, V. Scarpine, I. Sevilla-Noarbe, M. Smith, E. Suchyta, M. E. C. Swanson, G. Tarle, C. To, M. Vincenzi, N. Weaverdyck, R. D. Wilkinson
Publikováno v:
The Astrophysical Journal. 944:43
The ultra-faint dwarf galaxy Reticulum II (Ret II) exhibits a unique chemical evolution history, with 72 +10/-12% of its stars strongly enhanced in r-process elements. We present deep Hubble Space Telescope photometry of Ret II and analyze its star f