by Victor Davis, Program Chair

September Meeting
The September, 2024 meeting of the AAAP will take place in Peyton Hall on the campus of Princeton University on Tuesday, September 10^th at 7:30 PM. As usual, the meeting is open to AAAP members and the public. Participants can join the meeting in-person at Peyton Hall or log in to the Zoom session as early as 7:00 pm to chat informally before the meeting begins. The evening’s guest speaker is Neta Bahcall, Eugene Higgins Professor of Astrophysics at Princeton University.

Options for Attending the Meeting
You may choose to attend the meeting in person or participate via Zoom or YouTube as we’ve been doing for the past few years. (See How to Participate below for details). Due to security concerns, if you log in before the host has set up internet connectivity in Peyton Hall, you may need to wait in the Waiting Room for a few minutes until the host is prepared to admit you into the meeting. You’ll need to unmute yourself to make comments or ask questions. It’s polite, though not required, for you to enable your camera so other participants can see you. A week or so after the meeting, the video of the lecture and Q&A will be posted on AAAP’s public YouTube channel.

Meet the Speaker Dinner
The status of the club’s traditional “Meet the Speaker” dinner is undetermined at this time. Please contact the Program Chair closer to the meeting date if you’d like to attend.

Getting to Peyton Hall
The parking lots across the street (Ivy Lane) from Peyton Hall are now construction sites, unavailable for parking. We’ve been advised by the administration of the astrophysics department that we should park in the new enclosed parking garage off Fitzrandolph street and walk around the stadium and athletic fields. Here’s a map of the campus and walking routes from the parking garage to Peyton Hall. The map shows the recently completed East Garage. Not shown is an access road Sweet Gum that connects from Faculty Road to an entrance at the lower left corner of the garage. Stadium Road connects from Fitzrandolph Road to another entrance at the opposite corner (and higher level) of the garage. It’s about a 10-15 minute walk from the parking garage to Peyton Hall.

Lighting Up the Dark: Where is the Dark Matter?
Gravitational lensing and other phenomena help to show the distribution of mass within galaxies and throughout the universe, revealing the connection between the dark and bright sides of the Universe. We’ve discovered that – at galactic scales – the observed mass distribution extends considerably beyond the dimensions we observe in luminous objects. This trend changes dramatically at scales larger than a few hundred kiloparsecs, where mass, light, and stars trace each other remarkably well. Contrary to earlier expectations, it seems that most of the dark matter in the universe may be located in large halos (~300 Kpc in extent) enveloping and surrounding galaxies as opposed to being found on larger scales throughout galaxy groups, clusters, and other large-scale structures.

How can stars, which represent only about one percent of the total mass of the universe, follow the total mass so well? Where are the rest of the baryons? How is dark matter distributed in the universe, and how does it relate to the underlying distribution of light, stars, and baryons? Prof. Bahcall will discuss the connection between baryons, stars, and mass at large scales, and the implications for galaxy formation, the mass-density of the universe, and cosmology.

Neta Bahcall
Neta A. Bahcall is the Eugene Higgins Professor of Astrophysics at Princeton University. She is Director of the Undergraduate Program in Astrophysics, and past Director of the Council on Science and Technology of Princeton University. 

Prof. Bahcall was born in Israel. She earned her PhD from Tel-Aviv University, working in Nuclear Astrophysics under the direction of Prof. William A. Fowler of Caltech. She was the first Head of the Science Program Selection Office and Chief of the General Observer Branch at the Space Telescope Science Institute (STScI) in Baltimore. Prof. Bahcall is a Distinguished Lecturer at various universities and has served on editorial boards of many organizations. She’s an elected member of the National Academy of Sciences, and past-chair of its astronomy section. She has won prestigious awards for her distinguished career in astronomical research. Prof. Bahcall married renowned astrophysicist John N. Bahcall in 1966, and has three children. 

Prof. Bahcall’s research work focuses on questions such as: What is the large-scale structure of the universe? How did structure form and evolve? How much dark matter exists in the universe and how is it distributed? What is the nature of dark energy? What is the ultimate fate of our universe? Prof. Bahcall and colleagues’ determination of properties such as the cluster correlation function, the cluster mass function and its evolution, the mass-to-light function from galaxies to superclusters, the geometrical shapes of clusters and of large-scale structure have provided powerful constraints on cosmology, including one of the first determinations of the mass-density of the universe and the amplitude of mass fluctuations. Prof. Bahcall works closely with students and postdoctoral fellows; their work is summarized in more than 300 scientific publications.

How to Participate (Links)

Zoom and YouTube links will be provided soon

As always, members’ comments and suggestions are gratefully accepted and much appreciated.

victor.davis@verizon.net
program@princetonastronomers
(908) 581-1780 cell