Collection of 2017-18 dues: 11

Collection of money for 31 of 32 orders of ACA logo Polo shirts

Signup sheets for Eclipse Stations

Meeting:

President, Kenneth Beard welcomed all to our meeting and recognized the ACA officers that were present. 

Kenneth then introduced the night’s main speaker Suzanne Hayward Harris.

Suzanne’s program was titled “The Egg Beaters of Space: Helium-Core White Dwarfs, Binaries, and Globular Clusters”

Her presentation included the following points:

·         An explanation of what a White Dwarf is:

o   White Dwarfs are former stars that no longer have fusion occurring at their core

o   White Dwarfs are made of electron-degenerate matter – “Extremely dense non-interacting matter”

·         Discussion of the life cycle of a star

·         Discussion of the difference between Carbon-Oxygen versus Helium Core White Dwarfs

·         Discussion of the two ways that Helium Core White Dwarfs are created

o   A Star is too small to become a red dwarf. This take trillions of years so no White Dwarfs exist that are made this way

o   HC White Dwarfs can also be formed from Binary Stars, where one star strips away the fuel from the other.

·         Three types of Binaries

o   Visual

o   Spectroscopic

o   Eclipsing

·         Discussion of the way Mass Transfer occurs between binaries

o   Accretion Disk vs Common Envelope

·         Discussion of Star Clusters and their relation to White Dwarfs

o   Globular vs. Open Star Clusters

·         Globular Clusters are likely homes for White Dwarfs due to their density

o   During evolution the core of the globular cluster large stars tend to move outward, while the core collapses pushing smaller stars closer together.

o   Star distance becomes 1 Light Year on average.  The chance of Stellar Flyby’s increase allowing for Binary Interaction and ultimately Mass Transfer.

·         Discussion on how to search for and identify Helium Core White Dwarfs among millions of stars in a galaxy. 

·         Summary: Helium Core White Dwarfs must be formed in close binary formations because the universe is too young for them to exist by other methods. 

Suzanne recommended watching the video explaining Hertzsprung-Russel Diagram which is commonly used in the search for White Dwarfs. 

The video can be found at www.spacetelescope.org, or by searching for Hertzsprung-Russel Diagrams on the web.

Suzanne answered several questions at the end of her presentation, and offered to entertain questions and discussion during refreshments.

Our formal meeting concluded at ~8:30pm.

Many thanks to Maryglenn B for providing great refreshments, including chips, dip, sweets, sodas, and Healing Springs water.

We enjoyed great conversations.  Some went outside to observe the sky.

Respectfully submitted,

Shane Sherwood

20170624ACATHMin

The Astronomy Club of Augusta met on June 24, Saturday at Nine Mile Range-Dark Sky Observatory for two events.

There were  15  members in attendance.