Astronomy Colloquium

Understanding the formation and evolution of the first stars andgalaxies is one of the most exciting  frontiers in astronomy. Since the universe was filled with neutral hydrogen at early times, the most  promising method for observing the epoch of the first stars is using the prominent 21-cm spectral  line of hydrogen. Current observational efforts are focused on a cosmic age of 500 million years,  with earlier times considered much more challenging. We show that stars from a much earlier era  may be observable as a result of a recently noticed effect of different motions of the dark matter and  the baryons in the early universe. We produce simulated maps of the first stars and show that these  relative motions significantly enhance large-scale fluctuations and produce prominent structure on  the scale of a degree in the 21-cm intensity distribution. The particular signature of this structure
 should make it easier to confirm the existence of million solar-mass halos at early times.