Franziska Laatz Universitaet Hamburg

Dark Star atmospheres with PHOENIX (pdf)

It is predicted that the first stars in the history of the universe formed in mini halos of 10^5 to 10^6 sun masses, which also contain a reasonable amount of dark matter. Theses stars are predicted to be very massiv (M > 100 M_sun). It has been proposed that self-annihilating dark matter could provide an additional source of energy during the formation, producing a new type of stable object, a dark matter powered star (Dark Star).The properties of such a Dark Star may be altered in comparison to a normal Pop III star. Dark Stars are predicted to be cooler, larger, more massive and potentially longer lived, due to their additional energy source. There have been several approaches to calculate the properties of such Dark Stars. Using the PHOENIX atmospheric code. I calculate the spectra of stars for a wide range of Temperatures. PHOENIX is able to calculate atmospheres for all interesting temperatures (if gravity is high enough). PHOENIX is able to calculate the radiative transfer in the non-local thermal equilibrium and also includes several advanced line broadening options (Stark broadening and van der Waals broadening). Using the Phoenix spectra, the detectability of such stars via the James Webb space telescope can be calculated considering the sensitivity of the near infrared camera. Results of this study will be presented, and the implication for the detectability of the Dark Stars with the JWST will be discussed.