JULY 2 - 6, 2007

THURSDAY, JULY 5

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.

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.

VISITING SCIENTISTS

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

JULY 9 - 13, 2007

THURSDAY, JULY 12

4:00 pm: Summer Colloquium Series. "Reflections from Outbursts of Supermassive Black Holes at the Centers of Galaxies," Dr. Christine Jones, CfA. These talks are aimed at undergraduate summer students, but all CfA staff and visitors are welcome. Preceded by refreshments at 3:30 pm. For more information, contact Jonathan McDowell (jcm@cfa, 5-7176). Phillips Auditorium.

FRIDAY, JULY 13

12:30 pm: Radio and Geoastronomy Division Lunch Talk. "VLBI with the SMA: Probing the event horizon of Sgr A*" Jonathan Weintroub, CfA. Room M-340, 160 Concord Avenue.

Abstract: A unique and challenging opportunity exists to observe the immediate neighborhood of the super massive black hole in the center of our galaxy (Sgr A*) at a resolution comparable to the size of its event horizon. At a wavelength just below 1 mm the flux density from the galactic center peaks, the emission is relatively unaffected by turbulent scattering in the intervening plasma, and the opacity is low. At 0.8 mm and with 5000 km baselines the angular resolution of an interferometer approaches 20 microarcseconds, the finest resolution available in any astronomical waveband. We are building a phased array processor and VLBI recording interface which we plan to retrofit to the SMA in 2008. This equipment will allow the SMA to function as a high frequency VLBI station with its full collecting area. In 2006 we installed a hydrogen maser time standard at the SMA site. Fiber connections between the SMA and the CSO and JCMT already exist, so those facilities can also participate in phased array VLBI observations. Thus the SMA has the potential to become the center of submm wavelength VLBI on Mauna Kea, providing the critical longest baselines. In this talk I will make the case for submm VLBI observations of the galactic center, and describe the planned instrumentation retrofit. In April 2007 we observed at 1.3 mm with a 3-element ad-hoc VLBI array. The JCMT reflector was used on Mauna Kea, with the SMA generating the maser locked LO reference, and housing the Mark5b VLBI data storage equipment. The other stations were the SMTO (Mount Graham, AZ), and a single CARMA dish (Cedar Flat, CA). I will conclude by showing and discussing some initial detections from this observation.

SAO HUMAN RESOURCES NOTES

Leave Donations Requested

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.

VISITING SCIENTISTS

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

JULY 16 - 20, 2007

MONDAY, JULY 16

12:00 pm: "Coronal Loop Modeling for Hinode and SDO" , Piet Martens (Montana State University) Pratt

Abstract: I will describe analytical and numerical coronal loop modeling efforts, and data analysis, carried out by myself and graduate students at MSU. Our immediate effort is geared towards producing multi- stranded loop models that can reproduce the unprecedented high spatial, temporal, and spectral resolution observations of coronal loops made by XRT and EIS on Hinode and by TRACE. I will show analytical solutions for the temperature profile of loops for a wide range of heating functions, that hold up very well against the results of a fully time-dependent hydro code. The analytical model allows us to produce Differential Emission Measures at each loop pixel for many-stranded loops, with minimal computational effort. One salient result of our analytical solution, is that we confirm the validity of the now almost 30-year old Rosner, Tucker, and Vaiana scaling for the whole array of heating functions considered, and that unexpectedly, the constant of proportionality in PL ~ T3 turns out to be a very good diagnostic for the spatial distribution of the heating.

WEDNESDAY, JULY 18

12:00 pm: "Coronal X-ray Flares, Abundances and Human Color Vision", Raanan Nordon (Technion, Israel) Pratt

Abstract: The study of stellar X-ray flares has been given a great boost since the launch of the hi resolution telescopes XMM-Newton and Chandra. It has since been observed that many stellar coronae exhibit abundance fractionation different from Solar. While in the Solar corona, low first ionization potential (FIP) elements seem to be enriched compared with the photosphere, some other stars show an inverse effect - a depletion of low FIP elements compared with high FIP elements. A few studies have linked this change of abundance pattern with X-ray activity. We analysed a sample of flares from XMM-Newton and Chandra archives looking for evidence of abundance variations during large flares. The results are discussed.