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 Welcome to the
Peninsula Astronomical Society's
web site.


The Peninsula Astronomical Society is a group of some 200 Bay Area astronomy enthusiasts of all ages and backgrounds. Some members are professionally trained in astronomy, others are just starting and have never looked through a telescope before. One thing that we all have in common is an interest in the sky.

The PAS holds meetings on the second Friday of each month at 7:30 pm on the campus of Foothill College in Los Altos Hills, CA (between San Jose and Palo Alto).  The meetings are usually held in Room 5015, next to Parking Lot 5 (see map). Each meeting features a speaker (or speakers) bringing us up to date on different topics in astronomy. The public is welcome to attend these meetings; there is no charge to attend.  Note, however, that there is a $3 charge for parking - visitor parking permits are available from the machines in the parking lots.  Please do not park in spaces marked "Staff" - you will be ticketed!

As part of its commitment to bringing astronomy to the public, the Peninsula Astronomical Society operates the Foothill College Observatory (click here for more information). The Observatory is staffed by members of the society who volunteer to conduct the regularly scheduled public programs.

In addition to operating the Foothill Observatory, the PAS has its own observatory in the nearby Santa Cruz Mountains. This location has AC power and room for members to set up their own telescopes at our monthly star parties. This site is also the home of the society's 12" telescope, available for member use after a checkout.

For informaton about membership in the PAS, click here.





"Galaxy Simulations and

the Circumgalactic Medium"



by Bryan Wang and Rishi Dange of the Harker School.

Friday June 14th, 2019 at 7:30pm

NEW VENUE - Los Altos Public Library

ADDRESS is  --  13 S. San Antonio Road, Los Altos, CA 94022

The driveway is just one block south of the San Antonio - Main Street intersection. FREE Parking!


ABSTRACT --  In recent decades, cosmological simulations have played an increasing role in the expert understanding of galaxy formation, but while simulations have improved dramatically, many parameters such as the strength of stellar and supernova feedback are not well determined. The circumgalactic medium (CGM), the gas outside of the galaxy disc but within the dark matter halo, could be an effective probe of feedback models due to its high ionization level and low density. However, since the CGM does not form stars and is usually detected in absorption spectra, instead of simulated telescope image comparisons, a more specialized methodology is needed. This work analyzes the CGM of many simulated galaxies using the random sampling of sightlines throughout a spherical volume surrounding them, emulating absorption spectra. We determine each sightline using two points: the starting location is chosen uniformly over the surface of the sphere and the midpoint is uniformly distributed throughout the bulk of a smaller concentric sphere. We project along this line of sight and use ionization calculation software TRIDENT to determine the column densities of ions situated in the line. Since we can make a large number of individual sightlines, many statistical properties can be examined, covering the full spectrum of redshifts, star formation histories, masses, and other macroscopic parameters of the simulated galaxies. These properties can be directly compared to observed absorption data, and can therefore help constrain the parameters of these simulations and either improve confidence in their predictions or determine what physical models need to be adjusted.


SPEAKERS:  For the second year in a row, Rishi and Bryan are two high school research interns working under Clayton Strawn and Prof. Joel Primack at the University of California, Santa Cruz Astrophysics Department. They are rising high school seniors at The Harker School in San Jose, California.

Weather permitting, the OBSERVATORY at Foothill College will be open for public viewing

from 9 to 11pm,  just as it is every CLEAR Friday night throughout the year.





PAS Logo clothing and other cool items are available at Cafe Press - click on the T-shirt:

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