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

http://antwrp.gsfc.nasa.gov/apod/image/9611/puppisa_rosat_big.gif

Pulsars

• Rapidly spinning neutron stars

• Pulses light due to enormous magnetic field

• Magnetars are super magnetized spinning neutron stars

http://antwrp.gsfc.nasa.gov/apod/image/0411/magnetars_cobeloc_big.jpg

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

http://antwrp.gsfc.nasa.gov/apod/image/0412/m87_comp.jpg

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

http://antwrp.gsfc.nasa.gov/apod/image/0411/ngc2207_hst_big.jpg

Earth

Region of Normal Galaxies

Region of ActiveGalaxies

Region ofQuasars

to 10 Mcy to 1 Bcy