JANUARY 14 - 18, 2008

MONDAY, JANUARY 14

12 noon: Solar, Stellar, and Planetary Sciences Division Lunch Talk. "The Poisson Point Process: An Effective Tool for Radiative Transfer Problems," Rainer Wehrse, Zentrum fur Astronomie der Universitat, Heidelberg. Pratt Conference Room.

Abstract:In the talk, the Poisson Point Process that is well known in mathematical statistics is introduced and applied to the extinction due to a large number of spectral lines. We address in particular the calculation of the opacity distribution function from the line density, and the distributions of strengths and shapes. When the process is combined with analytical solutions of the radiative transfer equation it allows the very effective calculation of important mean values as, for example, of the radiative flux and acceleration and of the expansion opacity. Examples are shown for plane-parallel media that both absorb and scatter and are static or in differential motion. It is also demonstrated that the process allows easy insight into problems that are nearly impossible to treat numerically, such as the role of the myriad of missing lines in stellar atmosphere models.

THURSDAY, JANUARY 17

7:30 pm: Monthly Observatory Night for the Public. "Impact! Finding and Tracking Asteroid Threats," Brian Marsden, CfA. The lecture will be followed by telescopic observing, weather permitting. No tickets or reservations are necessary; however, seating is to the capacity of the hall. Doors open at 7:00 pm. Phillips Auditorium.

Abstract: In late 2007, astronomers spotted an asteroid with a chance of hitting Mars on January 30. Whether it strikes or not, this incident reminds us that we are in a cosmic "shooting gallery." How do astronomers find and track asteroids, and predict which ones may hit a planet? Brian Marsden, director emeritus of the Minor Planet Center, has the answers along with anecdotes from the scary to the amusing (that's no asteroid, it's a spacecraft!).

FRIDAY, JANUARY 18

12:30 pm: Radio and Geoastronomy Division Lunch Talk. "The Warm and Dense Gas of Embedded Low-Mass Protostars," Tim van Kempen, Leiden Observatory. Room M-340, 160 Concord Avenue.

Abstract: Embedded low-mass protostars, also known as the Class 0 and Class I evolutionary stages, have been studied extensively the last decade. Although much is known about the cold outer regions on scales of a few tens of thousand of AU from dust and gas studies, far less information exists about the inner regions, where the dense and warm gas is located. The dense gas in the center, close to where the material in the envelope accretes onto the central star and disk system, is studied using molecular lines with the new HARP-B array on the JCMT for a large sample of embedded objects in the L1688 region. Comparison between high density and cloud material tracers characterizes these inner regions of embedded sources. In addition, it is found that many sources thought to be embedded from (near)-IR studies, are not embedded, but confused by geometrical effects. The warm gas, with temperatures above 100 Kelvin, is studied using the new 650/800 GHz heterodyne array receiver CHAMP+ on the APEX telescope. Such studies disentangle the warm gas heated thermally from that shock heated by the outflowing gas. First results of CO isotopologues of a recently started project will be presented.

SAO HUMAN RESOURCES NOTES

CFC Contribution Deadline Extended

The deadline for making contributions to the 2007 Combined Federal Campaign of Eastern Massachusetts has been extended to January 15, 2008. If you wish to contribute to the 2007 Combined Federal Campaign, please return your pledge card in an envelope addressed to CFC, MS 17, no later than January 15, 2008. If you need a new pledge card or if you have any questions, please contact Anne LeBlanc at ext. 5-7371.

All organizations listed in the CFC brochure have met the stringent application guidelines outlined by the Office of Personnel Management. For more information please refer to http://www.opm.gov/cfc/. For a complete list of the local, national and international charities please refer to the 2007 CFC brochure of Eastern Massachusetts.

Federal and non-federal employees may use payroll deduction, cash or check to make pledges.

Leave Donations Requested

Due to a medical emergency, Joyce Janjigian of the Solar, Stellar and Planetary Science Division 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 Joyce should complete a Leave Donor Form and send it to MS 17.

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.