Astronomy C. Madison Brady

Transcription

1 Madison Brady Disclaimer: This presentation was prepared using draft rules. There may be some changes in the final copy of the rules.

2 Overview Stellar evolution and type II supernovae, as well as astronomical diagrams and calculation methods. Team of up to two Each team may bring: up to two three-ring binders of any size containing information in any form and from any source, attached using the available rings. Eye protection not required

3 Basics of This Event This year s focus is on stellar evolution and Type II Supernovae Students will be expected to be familiar with objects from the list and be able to identify them with the usage of images, diagrams, light curves, or other data Students should also be able to perform astronomical calculations

4 Changes From Last Year Focus is on Type II instead of Type Ia supernovae Type II result from the collapse of a massive star at the end of its life, Type Ia result from a white dwarf accreting enough mass to exceed the Chandrasekhar limit Examining different types of stellar objects More focus on large and late-stage objects (such as Wolf-Rayet stars, hypergiants, Cepheids, Luminous Blue Variables) New objects (elaborated upon in next slide)

5 New Objects - Star-Forming Regions NGC 6357 ( Lobster Nebula ), a HII region known for its very high population of extremely massive young stars NGC 7822, a HII region which contains an extremely hot eclipsing binary system and pillar-like formations known as elephant trunks

6 New Objects - Variables Alpha Orionis (Betelgeuse), a red supergiant semiregular variable. It is one of the brightest stars in the night sky. AG Carinae, a luminous blue variable and one of the most luminous stars in the Milky Way S Doradus, a Luminous Blue Variable in the LMC, prototypical LBV

7 New Objects - Binary Systems HR 5171, a system of three stars, two of which form an eclipsing binary system. The primary is a hypergiant and the largest known yellow star. Circinus X-1, an X-ray binary system containing a neutron star. It is one of the youngest observed X-ray binary systems.

8 New Objects - Stellar Remnants Geminga, a neutron star gamma-ray source. It was not identified as a neutron star until years after its discovery. M82 X-2, an X-ray pulsar with an exceptionally high luminosity possibly caused by the infalling of material along magnetic field lines. PSR B , a bright radio pulsar with very little gamma emission (essentially the reverse of Geminga)

9 New Objects - Supernova Remnants IC 443 ( Jellyfish Nebula ), a supernova remnant that is undergoing interesting interactions with surrounding molecular clouds DEM L241, a supernova remnant. It is a binary system, and its companion survived the blast. RCW103, a supernova remnant consisting of a very slowly-spinning neutron star (~6.5 hours)

10 New Objects - Supernova Remnants SN W49B, the most recent black hole in the Milky Way (with an age about a thousand years as viewed from Earth) SN 1987A, a nearby supernova which allowed astronomers to study the process of a supernova in detail ASASSn-15lh, a bright object. It may be a Type 1 supernova or a tidal disruption event around a black hole.

11 Key Formulas Kepler s third law Parallax Hubble s Law Luminosity Blackbody Radiation Distance Modulus Cepheid Period-Luminosity Relationship

12 Coaching Tips Familiarize students with all of the objects from the list. Identify and teach key equations, practice calculations using tests from past years. Students typically have the most trouble with computation, so get lots of practice! Intuitively understand the basics of stellar evolution for several different star masses. This way, even if the student does not know the specific answer to a question, they can at least make an informed guess based off of what they know is possible.

13 Common Pitfalls Common ways to lose points on tests: Misidentifying objects (if subsequent questions are about the object, a bad ID can ruin your score) Mis-copying formulas or generally not understanding calculations (this event can be heavily computational, students should understand how to compute basic values or else lose lots of points) Misusing units (for example, substituting a luminosity into the magnitude equation can cause quite a headache, and mistaking kilometers for astronomical units can make an answer many orders of magnitude off)

14 Example Questions Given an image of a light curve, determine what type of variable a star is. Describe what causes the mass-loss of a Wolf-Rayet star. Describe a typical gamma-ray binary system. List two theories regarding the nature of ASASSn-15lh. Given an image of a star with a scale bar, determine its width in AU. Use this derived radius to calculate its apparent magnitude, knowing that its temperature is 3000 k and it is 30 ly from Earth.

15 Resources Science Olympiad Student Center - Astronomy Wiki, Question Marathons, Test Exchange Science Olympiad National Website Outside Websites: Chandra, NASA, Hubble Univ. of California, San Diego, Center for Astrophysics and Space Sciences Website