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Astronomy 2014 – Part 1
This is the National Science Olympiad (NSO) Astronomy C 2014 Event which gives an overview
of the content for the competition in Orlando, Florida on May 17th, 2014. The presentation
will provide regional and state event supervisors, coaches and teams the information to locate
and acquire the resources necessary
to prepare for competition. The focus for the 2014 astronomy event is
Stellar Evolution and Variable Stars. I am Donna Young, the National Event Supervisor
for Astronomy and my co-event supervisor is Tad Komacek, a doctoral student in geophysics
and planetary science at the University of Arizona in Tucson AZ. If you have any questions
you can email either one of us, unless the question is specific to the event description.
Any questions about the event description need to be asked through the rules clarification
link on the NSO website. This event has been supported by the Chandra
X-ray Observatory since it became an event in 1999. This webinar, as well as previous
Astronomy Event webinars, are posted on the Chandra website. Some of the deep sky objects
are also on this website, along with some stellar evolution materials and the HR Diagram.
This event is also supported by the American Association of Variable Stars Observers (AAVSO),
also located in Cambridge, MA. On the AAVSO website the astronomy and Reach for the Stars
(RFTS) events from the past 3 years are posted so teams can down download them to use for
study materials for the 2014 competition. The Variable Star Astronomy curriculum is
also posted on the AAVSO site and will be extremely beneficial as a resource. The H-R
Diagram plotting activity would also be beneficial for this event. Some of the deep sky objects
in this event are located on the AAVSO website in the Variable Star of the Season archive.
The 2014 event is Stellar Evolution and Variable Stars and there is no change in the event
parameters. Each team is allowed to bring either 2 laptops, or 2 three-ring binders
or 1 laptop and 1 three-binder. Teams can substitute an IPad or a tablet. Use of the
internet is not allowed under the general NSO event rules.
The words in red are the topics and deep sky objects (DSOs) that are different from last
year. If you have been participating in this event for the past 2 years you will notice
that some of the new topics/objects were in this event in 2012. In 2012 Stellar Evolution
and Type 1A Supernovas was the focus for the Astronomy, and in 2013 Stellar Evolution and
Type 2 Supernovas. All stellar evolution stages have been covered the past two years. Most
variable stars types were also covered in 2012 and 2013. Only two of the classes of variables are different. The
emphasis this year are the transitional regions on the H-R diagram – the variable stars
that and transitional stages from one stellar evolutionary stage to another stellar evolutionary
stage. Study the H-R diagram transitional regions, the regions of instability – that
is the major focus of this year’s competition. This simple schematic is a classification
of the some of the major classes of variable stars. The General Catalog of Variable Stars
has hundreds of classes and sub classes. Included in the 2014 competition are two categories
of intrinsic variable stars, the stars that are varying in brightness due to instabilities
within the stellar atmospheres and/or stellar cores. There are two major groups of intrinsic
variables – the pulsators and the cataclysmic variables. There are three major categories
of pulsating variables: the Cepheids, the RR Lyrae, and the Long Period Variables. There
are two types of Long Period Variables – the Mira’s and the Semiregulars. All these variables
are included the 2014 event, along with three different types of cataclysmic
variables (supernovas, recurrent novas and dwarf novas) and two classes of eruptive variables
(T Tauri stars and S Doradus). This is the list of deep sky objects (DSOs) for the competition.
There are two pulsators – Mira, a Mira variable star, and V1 a Cepheid variable star. T Tauri
and Ori1647 are eruptive variables associated with
proto-stars and Eta Carinae, an S Doradus variable star which is also classified as
a luminous blue variable star (LBV). There are six different cataclysmic variable
stars this year: two Type II supernovas, two Type 1a supernovas, a dwarf nova and a recurrent
nova. There is also one X-ray binary, two white dwarf binary systems, two planetary
nebulas, two globular clusters, and one star formation region, the Trapezium.
Mira is not only an example of a Mira variable star. It is the prototype of all Mira variable
stars. It is a pulsating red giant, a stage that Sun-sized stars go through when they
run out hydrogen, core fusion stops, and they transition from the main sequence to the red
giant branch. The region on the H-R where stars transition from the main sequence to
the red giant branch is called the Mira instability strip. In this region the stars become unstable
and pulsate. This image of Mira is from the Galex mission. The ultraviolet image shows
the debris ejected from the atmosphere of the star during the pulsations as it moves
through space-time under its own proper motions. The next image is from the Chandra X-ray mission.
An artist’s illustration of the observational data shows that Mira is not only a Mira variable
star, but also has a white dwarf companion that is accreting material from the outer
envelope of Mira’s atmosphere. If material from the accretion disk drops onto the surface
of the white dwarf, a nova situation could develop, and if enough material drops onto
the surface that the white dwarf approaches Chandrasekhar limit and it can no longer exist
as a white dwarf, the result would be a Type Ia supernova.
V1 is a Cepheid variable in the Andromeda galaxy. This Hubble image shows V1 as it varies
in brightness over time. This is the variable star that, sort of, made the universe into
a very large place. This is the one that when Edwin Hubble discovered the period of this
Cepheid variable star, determined the distance and discovered that it was not a galaxy far,
far away. They then knew those little smudges in space time were not just nebulae within
the Milky Way galaxy but other galaxies. 47 Tucanae is a globular cluster in the southern
hemisphere, visible with the naked eye. It has a dense core of stars with many exotic
stars. It was thought that globular clusters were a dead end place, as globular clusters
were left behind in the halo when the galaxy collapsed into its flattened disk shape, so
globular cluster stars are older highly evolved stars. However, all stages of evolution are
present within globular clusters and Tucanae 47 contains a bunch of exotic black hole binary
X-ray binaries. NGC 1846 is a very interesting globular cluster located in the Large Magellanic
Cloud and contains a planetary nebula. Scientists think that the planetary nebula is part of
the globular cluster and not just an accidental lineup between Earth and NGC 1846. There is
a large range of age disparity of the stars in this cluster, however the stars have the
same metallicity and it is thought that two globular clusters coalesced together to form
NGC 1846.