Charlottesville Astronomical Society
April Meeting Minutes
April 5, 2006
McCormick Observatory
Attendance: 35
Guest Speaker: Dr.
Kelsey Johnson (UVA Astronomy Dept.) – The Most Extreme Modes of Star Formation
in the Universe
Club Business:
•
48 paid active members
•
Checking account: $1958.10
•
See Larry Saunders for information on discounted
subscriptions to Astronomy and Sky and Telescope
•
Public Outreach:
Group Nights at McCormick (April 13 & 27)
•
Introduction to Amateur Astronomy
- April 20
at AHS
•
Scheduled Observing
- April 28
– Open House at Fan
Mountain
•
Astronomy Day, May 6
Messier Marathon Update
•
Re-Schedule for July?
with 90+ objects
•
Winner will be drawn from the names of club members who
find 50 objects
•
Atlas donated by Tom Ayers
Coffee Mugs are now being given out. One free to all CAS members. Mugs are given out at monthly meetings…first
come, first served.
T Shirts with CAS Logo on Chest and Horsehead
on back are now on sale for $8.50
Upcoming Speakers:
•
May: Jack Koester
(CAS Member) – Antique Telescopes
•
June: Don Wells
– NRAO
•
July: Ed Murphy
- Eclipses
Astronomy Retreat
2006:
•
Mark your calendar now for the weekend of August 25 –
27 at Bear Mountain Retreat in Highland
County
•
Email pre-registration began today. Make sure Richard Drumm
has your name if your interested. See website for pictures of past retreats.
10 Minute Topic:
John Avellone gave brief
presentation on “Solar Observing Basics”.
10 minute topic of next month “Various types of telescope mounts”, Wes Epperly.
Web Site of the
Month:
Universe Today
Notes from Guest Speaker’s Presentation:
“The Most Extreme Modes of Star Formation
in the Universe”, Dr. Kelsey
Johnson (UVA Astronomy Dept.).
An
abstract of this presentation can be found here.
Stellar Ecosystem.
Most
stars form in clusters. To understand
star formation in general we need to understand the cluster mode.
A fossil in the Milky Way.
Globular clusters. >10billion years old. A few parsec in size,
~10^4-10^5 stars. How were these
incredible objects formed?
Theoretically
it is difficult to theorize how these clusters formed. Understanding globular give
us insights into early universe.
So.. Globulars are the most extreme form of star formation.
First clue to formation of Globulars. Globulars live in the halos of galaxies. All the other stars live in the disk. This tells us that they formed before the
galaxy existed as we know it.
Second clue. Their
creation requires incredible pressures and densities in order to produce
massive clusters that are this compact that can survive the age of the
universe. When there are supernovas. The
material expels from the cluster…as the supernovas happen, material is ejected
from the cluster…if too many are lost then the gravity weakens and the globular
falls apart. So it is real important
that a globular uses all of the available mass in the area when they are
formed.
They
need high pressures to form.
The evolution of a globular cluster. The bigger and fluffier it is …the less time
it will survive. They can only survive
in the halos of galaxies because if the they interact
with too much stuff then they are broken apart with time.
So
how do we get Globulars? How do we get the
high pressures? Galaxies collide!
We
previously thought that Globulars only could form in a very old universe…but
through the use of Hubble has shown us that they can also form when galaxies
collide.
Adolescent
Globulars are called super clusters
Galaxies
are quite social and interactions are common.
In fact our own galaxy is shredding up the large and small Magellanic Clouds…
Simplified
diagram of hybrid hierarchical galaxy formation of evolution,
First
clumps form after big bang -> massive stars form proto galaxies with small
disks -> mergers -.proto galaxies merge ans the
disks are destroyed then it either branches off as a large spiral in isolation or large ellipticals from merging and interactions.
Why
are “super” star cluster clusters interesting?
Extreme
mode of star formation
Plausibility
proto-globular clusters
Formation
common in early universe
Impact on the ISM &IGM (Interstellar medium, and intergalactic
medium).
When
these clusters are formed…there will be many massive stars born on the same
day, and they will die on the same day.
The
nearest starburst: m82 ~3.6 Mpc
M82
is exploding because of super star clusters, as seen in other wavelengths.
Super
star clusters have the biggest impact on the smallest galaxies.
Examples
of exploding galaxies:
NGC159, NGC1755, He2-10
Can
globular clusters formation provide insight about the early universe?
In principle yes.
The
problem is that star formation occurs within dense clouds of gas
Showed view of star-formation cloud transitioning from visible
light to far- infrared light.
Things like Spitzer Space Telescope are providing this
data.
Beyond
the visible
Observational
strategy-if we want to understand star formation, it’s not a bad idea to
observe them while they are forming.
Early formation may be viewed in infrared…then later with visible after
they have been formed.
SBS
0335-052…one of the most important galaxy in the near by universe. We think that this is similar to how early
galaxies look. There is
very low amounts of heavy elements.
So they are looking for super star clusters that can form in that type
of environment.
Showed
movie of embryonic star formation
Future
– golden time
Cutting
edge observatories
Expanded very large array starting ~2007
~20x
more sensitive then the very large array (Socorro, NM. Socorro means help)
If
Hubble (Space telescope) dies then the hay
day of optical astronomy is over… next planned orbiting telescope is 20 years
out. Large ground based telescopes are
too expensive (30meter size = billion dollars)
Only
the electronics are being upgraded at the VLA.
The existing computers are from the 70s…no mechanical upgrades..but with new
electronics…yields 20 times more sensitivity!
Atacama Large Millimeter Array (ALMA) (Early science ~2009, fully online~2012)
Altitude,
17,000 feet
~20
more sensitive than the VLA
~10x
the resolution of HST
Virtually
unexplored wavelength regime. Some of
the prototypes are being shipped down there now.
The ALMA Science center is operated by NRAO here at UVA.
There
were 60 antennas planned, but there will be 50 due to budget constraints.
