Science Olympiad

1. Science Olympiad Astronomy C 2007 Joshua Haislip

3. Stellar Nurseries Evaporating Gaseous Globules Shockwaves from distant supernovae or gravity from nearby stars can trigger collapse. Consists of dense regions of molecular hydrogen Pillars are left after ‘erosion’ from the intense ultraviolet radiation of nearby, bright stars around 3.5 light years

4. Protostars and Protoplanetary Disks 15 times Neptune’s orbit As gas collapses it heats up Before nuclear fusion and hydrostatic equilibrium is achieved, this ball of gas is known as a protostar The disk of swirling dust and gas orbiting this protostar/star is called the protoplanetary disk NICMOS Peers Through Dust to Reveal Young Stellar Disks. A View of IRAS 04302+2247 T Tauri Star Forming System

5. Brown Dwarfs Were not big enough to ignite nuclear fusion Turbulent stellar duds Less that 3% mass of sun TWA 5B

6. Red Dwarfs Slow rate fusion of hydrogen into helium in core Between 8% and 50% the mass of the sun Most common type of star in the galaxy Turbulent interiors Proxima Centauri: closest star to the sun

7. White Dwarf As red dwarf stars use up all of their fuel in the core, they cool down This allows for collapse -> they shrink to about the size of the Earth Process takes longer than the age of the Universe -> we have never this type of white dwarf

8. Sun-like Star Currently 70% hydrogen, 28% helium, and 2% other metals Fusion of hydrogen into helium is taking place in core 700 million tons of hydrogen are converted to helium each second

9. Red Giant When solar-type stars run out of hydrogen in the core, they cool and begin to collapse Collapsing causes temperature to rise, igniting a shell of hydrogen around the core Star expands over 100 times its original size, core collapses further igniting helium fusion The surface of our sun might swallow the Earth when it becomes a red giant

10. Planetary Nebula After helium is depleted in core, star blows off outer layers leaving behind hotter star High speed stellar winds from the new hot star slam into previously ejected material creating the nebula

11. White Dwarf The core will eventually collapse to a white dwarf

12. Type Ia Supernova Chandrasekhar limit: A white dwarf with more than 1.4 solar masses will collapse A white dwarf stripping material off a binary companion could result in breaking this limit Type Ia Supernova will result Tycho Brahe

13. Blue Supergiant Extremely massive stars with tremendous power output 20 times the diameter and 30 times the mass of the sun If we replace the sun with Rigel (blue supergiant in Orion) this is what would be seen from earth The sun as it appears from earth (compare with Rigel image to the left)

14. Red Giant When blue supergiants run out of hydrogen in the core, they cool and begin to collapse Collapsing causes temperature to rise, igniting a shell of hydrogen around the core Star expands over 100 times its original size, core collapses further igniting helium fusion The surface of our sun might swallow the Earth when it becomes a red giant Same as with solar-type stars

15. Blue Giant Unlike solar-type stars, as massive stars expand to red giants their outer layers are ejected leaving a blue giant, or Wolf Rayet star Similar to planetary nebulas, the new blue giant’s hot solar winds collide with previously ejected material creating nebulae Crescent Nebula

16. Type II Supernovae When a massive star runs out of fuel, it will collapse to either a neutron star or a black hole Energy released during the collapse blows the star apart

17. Neutron Star Only around 12 miles in diameter Extremely dense! 1 spoonful of neutron star material would weigh over 10 billion tons Some act as rapidly rotating lighthouses beaming radiation (puslars or Little Green Men)

18. Blue Supergiant Some blue supergiants are so large, they completely skip the red giant phase Eta Carina (depicted to the right) is around 100 times the mass of our sun and produces energy at a rate which if 5 million times that of the sun

19. Type II Supernovae When a massive star runs out of fuel, it will collapse to either a neutron star or a black hole Energy released during the collapse blows the star Cataclysmic variable Same as with Blue Giant star

20. Black Hole The densest objects in the universe When very massive stars collapse, nothing can stop them All mass is compressed to a single point in space

21. Blue Supergiant Most massive of all stars (around 150 solar masses) Violently unstable due to the amount of radiation they produce HD 5980

22. Black Hole The densest objects in the universe When very massive stars collapse, nothing can stop them All mass is compressed to a single point in space

23. Hertzsprung Russell Diagram

24. Hertzsprung Russell Diagram

25. Hertzsprung Russell Diagram – M55

26. Magnitude Astronomers measure the brightness of stars in magnitudes. In this magnitude scale, the higher the number, the fainter the object. There are two types of magnitudes: Apparent: magnitude of the star determined by how bright it appears from the earth Absolute: magnitude of the star determined by how bright it appears from 10 parsec away While it is easy to determine the apparent magnitude, astronomers are always looking for new ways to determine a stars absolute magnitude.

27. Intrinsic Variable Stars Excellent way of determining distances because astronomers have found a relationship between period and luminosity or absolute magnitude. This absolute magnitude can be calculated as a function of the variable’s period. Comparing this to its apparent magnitude one can calculate the distance with the distance modulus equation. Two main types: RR Lyrae Cepheid Variable

28. RR Lyrae Stars Population II stars (old, red stars and other objects found in the galactic halo and galactic bulge of a spiral galaxy Found in halos of galaxies -> globular clusters Periods are usually <1 day

29. Cepheid Variables Found in spiral arms Periods are usually much longer than RR Lyrae stars (from 5-75 days) Period of pulsation is directly related to its luminosity: the longer the period, the greater the mean intrinsic brightness

30. Extrinsic Variables Eclipsing Binary Binary star system in which the components periodically pass in front of one another as seen from Earth. Three types: Algol Star – constant/near constant brightness between minima W Ursae Majoris – continuous light variation, no clear start/stop to eclipse Beta Lyrae – brightness changes are fairly smooth and continuous

31. The Distance Modulus: • Kepler’s 3rd Law with Newtons addition: • where: • T = planet's sidereal period • r = radius of the planet's circular orbit • G = the gravitational constant = • M = mass of the sun • 1 pc = 206,265 au = 3.26 ly = 3.08 x 10^16m • 1° = 60 arcmin = 60´ ; 1´ = 60 arcsec = 60˝ • Inverse Square Law: L = 1/r^2 • Circumference, Area, Surface Area, and Volume of a Sphere

32. Most Importantly: Get the students excited about astronomy! Wikipedia Use Wikipedia to search for more information about variable stars and stellar evolution www.wikipedia.org Stellarium Free virtual planetarium! See the sky as it looks at any time in the future or past from any place on Earth. Also zoom in on planets and Messier objects to see them as they would look through a telescope. http://www.stellarium.org/ Test your students’ Stellarium skills with my “Stellarium Challenge” Test your students’ understanding of Kepler’s third law, as well as the weight equation with my lab “Measuring the Mass of Jupiter”: