Date

Talk

Thursday
April 9
4:30 PM
Reamer

Union's Historical Scientific Equipment

In this talk presented by Mandeville Gallery, Thomas B. Greenslade Jr., professor emeritus of Kenyon College, describes how he has worked to select and identify Union's early scientific equipment.

Note special time and place: Reamer Campus Center Auditorium, 4:30pm

Thursday
April 16

No Colloquium

Thursday
April 23

Solar Probe Plus Visiting the Sun and Living to Tell

Michelle Donegan
Johns Hopkins University Applied Physics Laboratory

NASA's Solar Probe Plus mission will be the first spacecraft to fly into the Sun's corona, giving us a view of the Sun's environment that has been on the "wish list" of solar physicists for over 40 years. The primary scientific goals of the mission are to understand how the corona is heated and how the solar wind is accelerated. During the mission, the spacecraft will orbit the Sun 24 times, gradually "walking in" toward the Sun with each pass and reaching a closest approach of 8.5 solar radii (3.7 million miles) from the Sun's "surface." At closest approach, the front of the spacecraft's heat shield will face temperatures approaching 2,000° C. Keeping the payload cool under these conditions requires an innovative design, and Solar Probe Plus will use a reflective but electrically insulating ceramic coating on the spacecraft's primary heat shield. Materials of this type are not commonly used in space, and their interaction with the space plasma environment can cause spacecraft charging to occur. The potentials on the spacecraft's surface must be controlled in order to minimize both disruptions to the spacecraft's functionality and disturbances of the very environment the instruments are attempting to measure. This talk will discuss the Solar Probe Plus mission and its science objectives and mission design as well as the spacecraft design and its impact on the spacecraft charging problem.

Friday
May 1

Steinmetz Symposium

Union Physics and Astronomy Students present their research

Thursday
May 7

White Dwarf Debris Disks and the Fate of Planetary Systems

Ted von Hippel
Siena College

After a brief introduction to white dwarfs and debris disks, I will present observations from the Spitzer Space Telescope and ground-based telescopes of metal-polluted white dwarfs with circumstellar debris disks. We measure the constituents of the debris disks, the elemental abundances of the material being accreted, and the accretion timescale. Our measurements support the idea that disruptions of asteroids created these debris disks. Based on the properties of these stars, I interpret the majority of the metal-polluted white dwarfs as resulting from planetary system bodies being ground down during the late stages of stellar evolution.

Thursday
May 14

Experimental Nuclear Astrophysics and Data Activities at Oak Ridge National Laboratory

Caroline Nesaraja
Oak Ridge National Laboratory

The research activities in the Experimental Astrophysics Group at ORNL involves tightly coupled work in three areas, measurements of nuclear reactions on unstable nuclei at the Holifield Radioactive Ion Beam Facility (HRIBF), nuclear data evaluation and the Computational Infrastructure for Nuclear Astrophysics (CINA). All three of these areas are directed toward improving our understanding of stellar explosions. The talk will cover some aspects of the radioactive ion beam facility (HRIBF) and will highlight some of the experiments that have been done in the past years. Also included in the talk are the data evaluation project and the online suite of computer programs (CINA) that enable rapid incorporation of nuclear physics results into astrophysical models.

Thursday
May 21

Lightening Up on Dark Energy

Natalia Connelly
Hamilton College

Dark energy, discovered almost 10 years ago, remains one of the most profound mysteries in modern physics and astrophysics. In my talk, I will review how spectacular stellar explosions called Type Ia supernovae can be used to map out the expansion history of the Universe and thus contribute to our understanding of dark energy. I will describe one of the proposed next-generation space-based experiments called SNAP that will collect hundreds of these supernovae to measure dark energy to unprecedented precision. I will also talk about some of the challenges of identifying Type Ia's that SNAP and other large-scale supernova surveys will have to face, as well as novel ways of addressing them.

Thursday
May 28

A Search for Chiral Symmetry Restoration  
                              or  
How to Lose Weight with Nuclear Physics 

Michael Wood
Canisius College

In  introductory  Physics  classes,  we  learn  that  weight  is  due  to  the  mass  of  an  object  in  a  gravitational  field.    The  mass  is  calculated  by  summing  the  masses  of  all  the  individual  pieces  that  make  up  the  object.    This  idea  works  well  for  molecules,  atoms,  and  even  nuclei.    For  hadrons  like  protons  and  neutrons  (constituents  of  the  nuclei),  this  rule  does  not  work.    The  masses  of  the  quarks  contribute  about  3%  to  the  mass  of  a  proton  or  neutron.    The  rest  comes  from  the  motion  of  the  quarks.   Some  theories  of  the  strong  nuclear  force  predict  that  the  mass  of  the  hadron  originates  from  the  breaking  of  a  certain  symmetry  called  chiral  symmetry.    In  the  early  1990s,  predictions  were  made  that  chiral  symmetry  will  be  restored  and  the  hadron  mass  will  be  reduced  when  the  hadron  is  inside  a  dense  nuclear  environment  like  a  Pb  nucleus.    This  talk  will  describe  an  experiment  that  was  a  search for chiral symmetry restoration by  producing light vector mesons in nuclei of  C,  Ti,  Fe,  and  Pb.    The  experiment  was  conducted  in  Hall  B  at  Jefferson  Lab  in  Newport News, VA.