Star Life Cycles and

Nuclear Science 2013 V2

31 Slides, I hope you like it.

(1 & 2) Kilometers

One kilometer = 1000 meters

Kilometers are used

to measure

distances on Earth.

www.bnsc.gov.uk/.../ae/earth_splash.jpg

(3 & 4) Astronomical Units

One Au is the average distance between the Earth and the Sun. The solar system is measured in Aus.

www.floridastars.org/icons/solsysna.gif

(5 & 6) Light Years

The Milky Way is measured in light years.

http://apod.nasa.gov/apod/ap960213.html

The Milky Way is 100,000 Light Years across

A light year is the distance light travels in one year.

(7&8) Parsecs

Parsec is short for parallax

second.Distances Betweengalaxies

are measured in parsecs.

http://www.smv.org/hastings/student2.htm

(10) Star Life CyclesThis theory explains why the stars we see have vastly different appearances.

Blue = young stars, yellow = middle aged stars, red = old stars.

(11,12 &13) Hertzprung – Russel (HR) diagram

The HR diagram plots starabsolutebrightness on the y-axis

and star surface temperature on the x-axis

(14 - 19) The Main Sequence

• Most stars including the Sun are in their mid-life.• Most stars including the Sun are plotted in the

main sequence of the HR diagram.

The Sun

Super-Giants

Giants

White Dwarfs

Main SequenceStars

(20 & 21) Apparent BrightnessThe apparent brightness is what a star looks like from Earth

http://hou.lbl.gov/~vhoette/Explorations/PleiadesStars/index.html

It depends on a star’s: Temperature, size, distance from Earth

(22 - 24) Mass and Life CycleThe life cycle a star will follow depends on its mass.

.

Super-giant stars such as Polaris end their lives in supernova explosions.

Small to medium stars like the Sun end their lives as white dwarfs.

(25 – 32) Life Cycle of the Sun

The sun is:

• a medium sized star

• 92% H and 8% He

• yellow and middle aged

• 5 billion years old

The Sun

When the H runs out,

the sun swells up to become

a Red Giant as large as

the orbit of Mars.

Yikes!

The sun will die in 5 billion years.

the sun will end its life

as a white dwarf, a dead star.

Red GiantWith

Oxygen & Carbon

Core

WhiteDwarf

31. (again)

A star is born when gravity crushes the nebula until fusion starts in its core.

32. Life Cycle of a starThe life cycle of a star depends on its mass

http://imagine.gsfc.nasa.gov/docs/science/know_l1/supernovae.html

At the end of the life of a super giant star, it explodes in the largest bang the universe has to offer.

33. Hertzprung – Russel (HR) Diagram

The HR diagram plots starabsolutebrightness on the y-axis

and star surface temperature on the x-axis

(34 & 35) Fusion

H + H He + energy

Fusion powers the stars

36. Radiation From the Sun

All stars radiate: Heat, (IR), Visible light (VIS) and Ultraviolet (UV) energy.

Solar energy travels to the Earth in waves.

http://www.solarviews.com/eng/comet.htm

Fast moving particles from the sun are

called the solar wind. They

push comet tails out

and damage

satellites.

37. What comes from Stars?Light and heat waves and

solar wind particles

Solar flaresand thesolarwind

The Earth’smagnetic fieldProtects the Earth from the

solar wind.

http://www.chabotspace.org/vsc/solar/spaceweather/curriculum/107_Magnetic%20Configuration.pdf

38. Spectra Lines

Each element makes a unique emission spectrum

Spectral lines tell us which elements are in a star.

Continuous Spectrum

Emission Spectrum

Absorption Spectrum

http://csep10.phys.utk.edu/astr162/lect/light/absorption.html

39. Gravity and Fusion are Balanced

During the main sequence, there is a balance between the nuclear fusion that wants to expand a star and

gravity that wants to crush it.

40. Star Color Shows Temperature

• Blue stars are young and hot• Yellow stars are middle aged and medium• Red stars are old and cooler

The Sun

41. First Matter After the Big Bang

The first element to form after the big bang was Hydrogen

http://www.webelements.com/webelements/elements/text/H/econ.html

The Hindenberg blew up because it was filled with Hydrogen

42. Creation of Elements Smaller Than Iron

Elements from Helium (He) to iron (Fe)

are made in stars by nuclear fusion.

43. Supernova 2001du Super giant stars end their lives with a huge explosion called a supernova.

Elements larger than Fe are fused together in supernovas.

http://www.rochesterastronomy.com/snimages/best_img.html

44. Stars Seen From Earth

On a clear night you can see about 6,000 stars without a telescope.

http://www.bbc.co.uk/science/space/myspace/nightsky/

Polaris

(45 & 46.) Polaris

• Polaris is a super giant

star that

points north.

• Polaris

is used

by sailors

to navigate.

http://www.astro.uiuc.edu/~kaler/sow/polaris-t.html

47. Electromagnetic SpectrumAll the wavelengths of energy from the sun.

Radio Waves, Micro Waves, Infra red, R,O,Y,G,B,I,V Ultra Violet, X-Rays, Gamma Rays

(48 - 50) Waves and Particles from the Sun

Energy waves from the sun include: Heat, (IR), Visible light (VIS) and Ultraviolet (UV) light.

http://www.solarviews.com/eng/comet.htm

Particles from the sun

called the solar wind

push comet tails out

and damage satellites.

(51& 52). Visible Light

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Low frequency

Long Wavelength

Low energy

High frequency

Short Wavelength

High energy

http://scifiles.larc.nasa.gov/text/kids/Problem_Board/problems/sound/sound_waves2.html

53. The Source of energy for all bio-geo-chemical –cycles on Earth is the sun

A powerful M9-class solar storm that unleashed a coronal mass ejection toward Earth in the early hours of Jan. 23, 2012 (GMT).Read more: http://www.foxnews.com/scitech/2012/01/31/with-suns-activity-set-to-diminish-is-global-cooling-coming/#ixzz1lEtainph

The sun powers most bio-geo-chemical cycles on the

surface of the Earth.

54. Energy on the Surface of Earth

Slide 31

The End