Zobrazeno 1 - 10
of 343
pro vyhledávání: '"Norris, John. E."'
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:
http://arxiv.org/abs/2305.05363
Autor:
Chiti, Anirudh, Frebel, Anna, Ji, Alexander P., Mardini, Mohammad K., Ou, Xiaowei, Simon, Joshua D., Jerjen, Helmut, Kim, Dongwon, Norris, John E.
We present chemical abundances and velocities of five stars between 0.3 kpc to 1.1 kpc from the center of the Tucana II ultra-faint dwarf galaxy (UFD) from high-resolution Magellan/MIKE spectroscopy. We find that every star is deficient in metals (-3
Externí odkaz:
http://arxiv.org/abs/2205.01740
Autor:
Chiti, Anirudh, Frebel, Anna, Simon, Joshua D., Erkal, Denis, Chang, Laura J., Necib, Lina, Ji, Alexander P., Jerjen, Helmut, Kim, Dongwon, Norris, John E.
The Milky Way is surrounded by dozens of ultra-faint (< $10^5$ solar luminosities) dwarf satellite galaxies. They are the surviving remnants of the earliest galaxies, as confirmed by their ancient (~13 billion years old) and chemically primitive star
Externí odkaz:
http://arxiv.org/abs/2012.02309
Autor:
Limberg, Guilherme, Rossi, Silvia, Beers, Timothy C., Perottoni, Hélio D., Pérez-Villegas, Angeles, Santucci, Rafael M., Abuchaim, Yuri, Placco, Vinicius M., Lee, Young Sun, Christlieb, Norbert, Norris, John E., Bessell, Michael S., Ryan, Sean G., Wilhelm, Ronald, Rhee, Jaehyon, Frebel, Anna
We analyze the dynamical properties of $\sim$1500 very metal-poor (VMP; [Fe/H] $\lesssim -2.0$) halo stars, based primarily on medium-resolution spectroscopic data from the HK and Hamburg/ESO surveys. These data, collected over the past thirty years,
Externí odkaz:
http://arxiv.org/abs/2011.08305
Stellar metallicities from SkyMapper photometry I: A study of the Tucana II ultra-faint dwarf galaxy
We present a study of the ultra-faint Milky Way dwarf satellite galaxy Tucana II using deep photometry from the 1.3m SkyMapper telescope at Siding Spring Observatory, Australia. The SkyMapper filter-set contains a metallicity-sensitive intermediate-b
Externí odkaz:
http://arxiv.org/abs/2001.07684
Autor:
Norris, John E., Yong, David
We explore the nature of carbon-rich ([C/Fe]_{1D,LTE} > +0.7), metal-poor ([Fe/H_{1D,LTE}] < -2.0) stars in the light of post 1D,LTE literature analyses, which provide 3D-1D and NLTE-LTE corrections for iron, and 3D-1D corrections for carbon (from th
Externí odkaz:
http://arxiv.org/abs/1905.04810
Autor:
Chiti, Anirudh, Frebel, Anna, Ji, Alexander P., Jerjen, Helmut, Kim, Dongwon, Norris, John E.
We present chemical abundance measurements for seven stars with metallicities ranging from [Fe/H] = $-$3.3 to [Fe/H] = $-$2.4 in the Tucana II ultra-faint dwarf galaxy (UFD), based on high-resolution spectra obtained with the MIKE spectrograph on the
Externí odkaz:
http://arxiv.org/abs/1803.01808
We investigate the color-magnitude diagram (CMD) of the Carina dwarf spheroidal galaxy using data of Stetson et al. (2011) and synthetic CMDs based on isochrones of Dotter et al. (2008), in terms of the parameters [Fe/H], age, and [alpha/Fe], for the
Externí odkaz:
http://arxiv.org/abs/1705.09020
Chemical abundances are presented for 19 elements in a sample of 63 red giants in the Carina dwarf spheroidal galaxy (dSph), based on homogeneous 1D/LTE model atmosphere analyses of our own observations (32 stars) and data available in the literature
Externí odkaz:
http://arxiv.org/abs/1705.09023
Autor:
Yong, David, Norris, John E., Da Costa, Gary S., Stanford, Laura M., Karakas, Amanda I., Shingles, Luke J., Hirschi, Raphael, Pignatari, Marco
We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system omega Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X
Externí odkaz:
http://arxiv.org/abs/1702.07087