The Physics department colloquia are usually on Friday afternoons at 3 pm in Room 135. Coffee and cookies are served at 2:45 pm in the same room. Anyone is welcome.<\/p>\n
Hunting the First Generations of Stars and Galaxies<\/strong> The new Australian SkyMapper 1.3m telescope is carrying out a photometric survey of the entire Southern Sky. From using an ugriz filter plus an additionally narrow filter placed at the Ca K line at 3933 \u00c5, stellar parameters can be obtained for all stars observed. This allows for an efficient selection of a variety of stellar types, including metal-poor stars. Recent efforts to search for the most metal-poor stars have indeed delivered a new record holder the the most iron-poor star: no iron lines were detected in the high-resolution follow-up Magellan spectrum and only an upper limit of [Fe\/H]<-7.1 could be determined. Contrary to its iron deficiency, the star has a significant amount of carbon. This abundance pattern can be explained with the star being a second-generation star in the universe which formed from a gas cloud enriched by only one PopIII first star. What was the environment in which these early stellar generations formed? A spectro-scopic study of the faintest dwarf galaxy Segue 1 has shed light on this question. Given the chemical abundance patterns of some its only few stars (with metallicities ranging from -4<[Fe\/H]<-1) suggest that this tiny galaxy may be a surviving first galaxy from the early universe.<\/p>\n This suggestion is in line with recent age measurements for similar ultra-faint dwarfs which showed these galaxies to be single-age stellar systems that are about as old as the universe itself.<\/p>\n","protected":false},"excerpt":{"rendered":" The Physics department colloquia are usually on Friday afternoons at 3 pm in Room 135. Coffee and cookies are served at 2:45 pm in the same room. Anyone is welcome. Hunting the First Generations of Stars and Galaxies Dr. Anna …<\/p>\n","protected":false},"author":63,"featured_media":0,"template":"","meta":{"_acf_changed":false,"_tribe_events_status":"","_tribe_events_status_reason":"","_tribe_events_is_hybrid":"","_tribe_events_is_virtual":"","_tribe_events_virtual_video_source":"","_tribe_events_virtual_embed_video":"","_tribe_events_virtual_linked_button_text":"","_tribe_events_virtual_linked_button":"","_tribe_events_virtual_show_embed_at":"","_tribe_events_virtual_show_embed_to":[],"_tribe_events_virtual_show_on_event":"","_tribe_events_virtual_show_on_views":"","_tribe_events_virtual_url":"","footnotes":"","uwm_wg_additional_authors":[]},"tags":[],"tribe_events_cat":[58],"class_list":["post-2606","tribe_events","type-tribe_events","status-publish","hentry","tribe_events_cat-physics-colloquia","cat_physics-colloquia"],"yoast_head":"\n
\nDr. Anna Frebel<\/strong>, Associate Professor, Dept. of Physics, Massachusetts Institute of Technology <\/p>\n