Signatures of the First Stars in the

We calculate the observable signatures of the rst generation of stars at high redshifts (5 < z < 10 3). We determine the cosmic star{formation history, using an extension of the Press{Schechter formalism for Cold Dark Matter (CDM) cosmologies, and calibrate the fraction of gas converted into stars so as to reproduce the C/H ratio observed in the intergalactic medium at z = 3. We nd that the Universe is typically reionized at z = 10 ? 20. Deep infrared observations with future space telescopes (SIRTF or NGST) will be able to detect bright star clusters and early quasars at z > 5. The redshift of these sources can be inferred from the redshifted Lyman{ limit or Ly breaks in their infrared spectrum. Finally, we calculate the signatures of intergalactic dust produced by the rst supernovae. We nd that the dust opacity of the intergalactic medium (IGM) to infrared sources at z > 10 could be of order unity.