The first stars must have formed from gas consisting of only hydrogen and helium, produced\u00a0in the Big Bang, with zero contribution from ‘metals’ – those elements heavier than helium that\u00a0are created at later epochs, by nuclear-burning in the cores of stars. We understand metals\u00a0to play a critical role at later epochs, in cooling the gas sufficiently that it can collapse to form\u00a0stars. The first stars must form differently from later generations, in as-yet poorly understood\u00a0ways. During their lives and deaths, the first stars played a significant role in reionizing the\u00a0cosmic baryonic material, in particular neutral hydrogen, and creating and then dispersing\u00a0metals far from the sites of early star formation. Stars less massive than around 80% of the\u00a0mass of the Sun live for essentially the age of the Universe and their surface chemical\u00a0abundances reflect conditions in the gas from which they form. Old, low-mass stars in nearby\u00a0galaxies thus probe early star formation. The first stars are also expected to form black holes of 10 solar masses or more, some of which can seed the growth of the supermassive black holes observed in the local Universe, and some of which may remain as stellar-mass black holes in present-day galaxies, powering ultra-luminous X-ray sources, and produce gravitational waves as binaries.<\/p>\n
The impact of the first stars on subsequent star formation and galaxy evolution depends on\u00a0many unknown quantities, including the relative distribution by number of their individual\u00a0masses (the Initial Mass Function, IMF), the properties of the dark matter halos within which\u00a0they are predicted to form, their environment – both the immediate surroundings and on larger\u00a0scales – and how they cluster. These issues form the basis of the proposed meeting, with\u00a0presentations of new results from observations relevant to the most metal-poor and oldest stars, as well as nearby stellar systems and the chemical enrichment of the intergalactic\u00a0medium. These observational discoveries will be discussed in the context of the results from\u00a0theoretical calculations of, for example, star formation in metal-free mostly atomic gas, the\u00a0IMF of the first stars, stellar evolution of the first stars, the properties of the first collapsed dark-matter halos, along with simulations of their evolution in a\u00a0 cosmological context. The\u00a0formation of seed black holes from the first stars and possible growth and evolutionary paths\u00a0to supermassive black holes and active galactic nuclei will also be discussed in one of the\u00a0sessions.<\/p>\n
Jean Brodie (University of California, Santa Cruz)
\nAnna Frebel (MIT)
\nZoltan Haiman (Columbia University)
\nAlexander Heger (Monash University, Australia)
\nMatthias Steinmetz (Leibniz Institute for Astrophysics, Potsdam, Germany)
\nRosemary Wyse (Johns Hopkins University)<\/p>\n
Registration will be possible via aspenphys.org<\/a>. The registration fee is $400.<\/p>\n","protected":false},"excerpt":{"rendered":"