Download - 4 Cosmic Objects
Cosmic Objects
http://www.aoc.nrao.edu/~fowen/M87_halo.html
Variable Stars
• Vary in luminosity on a regular basis
• Cephid variables period is related to magnitude
• Knowing magnitude you can compute distance
• "yardstick to the universe"
Henrietta Leavitt 1868 – 1921http://www.pbs.org/wgbh/aso/databank/
entries/baleav.html
Neutron Stars
• ~100 million in our galaxy alone
• 1-2 solar masses, 10 km diameter
• Emit high energy: X-rays and Gamma-rays
Pulsars
• Rapidly spinning neutron stars
• Pulses light due to enormous magnetic field
• Magnetars are super magnetized spinning neutron stars
http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html
http://antwrp.gsfc.nasa.gov/apod/image/0403/hudf_hst_big.jpg
Galaxies• Our solar system is a small part of a larger
galaxy made up of billions of stars- like our sun
• Millions even billions of galaxies are part of our Universe
• Galaxies take on shapes: elliptical, spiral, and irregular
• Galaxies occur in groups (local group), clusters many clusters form a super cluster
• ~100 billion stars
http://antwrp.gsfc.nasa.gov/apod/image/9906/ngc1365_vlt_big.jpg
Active Galaxies• Extremely violent processes taking place
• Unusual appearance, particularly of the nucleus
• Jets emanating from the nucleus
• High luminosity
• Rapid variability from compact energy source in the nucleus
• Differences in viewing angle influence how we see them
Radio Galaxies
• Powered by black holes
• Give off lots of energy in the radio wave portion of EM spectrum
Odd Galaxies• Quasistellar Radio Sources (star-like
radio sources)• or Quasistellar Objects objects QSOs• Quasars are powered by black holes
consuming stars at even greater rates than those in radio galaxies
• Quasars typically are farther from Earth than radio galaxies
• Quasars can be formed during galactic collisions
Earth
Region of Normal Galaxies
Region of ActiveGalaxies
Region ofQuasars
to 10 Mcy to 1 Bcy