MAY 28 - JUNE 1, 2007

TUESDAY, MAY 29

12:30 pm: Institute for Theory and Computation (ITC) Seminar. "The Stellar Populations of the Andromeda Spiral Galaxy," Dr. Jason Kalirai, University of California, Santa Cruz. Pratt Conference Room.

Abstract:: Simulations of hierarchical galaxy formation suggest that large galaxies such as the Milky Way and Andromeda (M31) should contain extended stellar halos that are chemically distinct (more metal poor) from the inner spheroid. Yet, no such population has been discovered in our nearest neighbor, M31. We report on the first results from a photometric and spectroscopic survey of red giant branch (RGB) stars over a large expanse in M31. Using a new technique based on photometric and spectroscopic diagnostics, we are able to isolate bonafide M31 RGB stars out to a distance five times further than previous studies (165 kpc). In addition to the kinematically cold disk and metal-rich inner spheroid, we find clear evidence for an extended, power law halo component in M31. The spectroscopic and photometric metallicity of this new population is measured independently and found to be metal-poor, [Fe/H] = -1.5. We also present the discovery of a new dwarf spheroidal galaxy in M31 and evidence for spatial and kinematical substructure in the halo. The discovery of this stellar halo puts to rest much of the disparity that has existed between the Milky Way and M31 halos.

THURSDAY, MAY 31

11:00 am: Science Education Seminar and Open Discussion. Weekly sessions focus on current department programs, literature reviews, and recent trends in science education and assessment. Some sessions feature outside speakers or guests. All members of the CfA community are welcome. Please contact Bruce Ward at bward@cfa, if you wish to attend any session. Phillips Auditorium.

11:00 am: Institute for Theory and Computation (ITC) Seminar. "Probing Inflation, Dark Matter, Dark Energy, etc. Using the Lyman-alpha Forest," Pat McDonald, CITA. Pratt Conference Room.

Abstract:: I summarize recent progress in the use of the Lyman-alpha forest as a cosmological probe. As a precise probe of the power spectrum of density fluctuations on megaparsec scales, the Lyman-alpha forest plays a critical role in constraining the spectrum of primordial density perturbations generated during inflation. Similarly, we constrain deviations from purely cold dark matter that affect structure formation, e.g., sufficiently massive standard neutrinos or warm dark matter. In the near future, large Lyman-alpha forest surveys can contribute to the study of dark energy and constrain curvature using the standard ruler provided by baryonic acoustic oscillations.

SAO HUMAN RESOURCES NOTES

Leave Donations Requested

Due to a medical emergency, Donna Coletti of the Library has been approved as a leave donor recipient in the Leave Transfer Program. Any SAO Trust Fund employee who wishes to donate annual leave to Donna should complete a Leave Donor Form and send it to MS17.

Under the Leave Transfer Program, Trust Fund employees may only donate annual leave to other Trust Fund employees and Federal employees may donate annual leave only to other Federal employees. If you should have any questions or are not able to access the form, please contact Anne LeBlanc, ext. 5-7371.

Job Vacancies

An online listing of all current SAO job openings is available. For more information, please call Human Resources, ext. 5-7371, or view your nearest bulletin board.

A list of scientists currently visiting the CfA is available here.