Transcript Sun
GEOL3045: Planetary Geology
Lysa Chizmadia
The Sun & Ulysses
Introduction
Image from: http://seds.org/nineplanets/nineplanets/sol.html
Mass = 1.989 x 1030 kg
99.8% of solar system
Diameter = 1.39 x 106 km
Temperature
5800 (sfc) - 1.56 x 107 K (core)
Class G star (G2V)
Population I star
metallicity high
Galactic velocity
2.17 x 105 m/s
Galactic period
2.25-2.5 x 108 a
Image from: asdictionary.blogspot.com
Spectroscopy
Pure white light yields continuous
spectra, like a rainbow
Individual elements produce line spectra
like fingerprints
Stellar Spectroscopy
Hot objects yields continuous spectra
Like a rainbow
Atoms emit light of specific wavelengths
Line spectrum
Individual to each atom (fingerprint)
Atoms in front of hot object, absorb light
at their fingerprint wavelengths
Absorption spectra
Images from: http://www.arm.ac.uk/~csj/pus/spectra/tot_l.html
Sun’s Spectra
Sun is relatively cool (T=5,500K)
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For comparison, Vega (T=10,000K)
Images from: http://www.arm.ac.uk/~csj/pus/spectra/tot_l.html
Sun Spots
Cooler parts of Sun’s surface
3800 K vs. 5800 K
22 year cycles
Image from: http://en.wikipedia.org/wiki/Sun
Change in magnetic poles
Differential rotation
Equator = 25.4 days
Poles = 36 d
Layers:
Image from:
http://seds.org/nineplanets
/nineplanets/sol.html
Image from: nmp.nasa.gov/ st5/SCIENCE/sun.html
Aurora
Borealis = north
Australis = south Images from: http://en.wikipedia.org/wiki/Aurora_(astronomy)
Interaction of solar wind with
Earth’s magnetic field
Particles have E from 1-100
keV
Collisions with oxygen
Green and red emissions
Collisions with nitrogen
Low level red and very high
blue/violet
Image from: http://en.wikipedia.org/wiki/Image:Aurora_australis_20050911.jpg
Ulysses Mission
Launched by NASA in 1990
Gravity boosts by Jupiter inImage
1992
from: http://ulysses.jpl.nasa.gov/
Sling-shotted out of ecliptic
Perihelion = 5.2 AU
Aphelion = 1.5 AU
Ulysses (con’t)
New solar cycle starting
Will be able to study sun spot cycle
How does a change in magneticImage from: http://ulysses.jpl.nasa.gov/
field effect solar wind, galactic cosmic rays & us
on Earth?
Mission highlights:
Observed 4 large coronal mass ejections merge into
large interplanetary shock wave
Feb 2005
Discovered e- jets from Jupiter
Feb 2006
Near pass with comet C/2006 P1 McNaught
Feb 2007
Summary
Sun is main sequence star
In mid-life
Population I star
High metallicity
Ulysses mission
Launched in 1990
Should reveal how changes in solar magnetic
field effect solar wind, background radiation
& current technology