Exploring Black Holes

A NASA EPO ProjectBrad Armosky

Karl Gebhardt

Mary Kay Hemenway

MJ Tykoski

UT Austin EXES Teachers© 2005 The University of Texas at Austin

McDonald Observatory

Illustration: NASA/CXC/M. Weiss; X-ray: NASA/CXC/MPE/S. Komossa et al.; Optical: ESO/MPE/S. Komossa)

Fast Write

What do you think are the most important characteristics of a black hole?

NEWS FLASH!

Astronomers Astounded by Super-Luminous Objects and Fast Moving Stars

Inside the Cores of Galaxies

Where is the quasar?

Where is the galaxy?

Markarian 205Quasar

NGC 4319Barred spiral galaxy

(system of billions of stars, gas, and dust)80 million light-years away

1 billion light-years away

Markarian 205Quasar

NGC 4319Barred spiral galaxy

(system of billions of stars, gas, and dust)80 million light-years away

1 billion light-years away

Foreground star inside our galaxythousands of light-years away

Distant background galaxy??? light-years away

What is one property of a quasar?

Compare the brightness of the galaxy core and the quasar.

Where is the quasar 3C-273?

Thanks to Sloan Digital Sky Survey www.sdss.org/sdss.html

A B C D

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Where is the quasar 3C-273?

Thanks to Sloan Digital Sky Survey www.sdss.org/sdss.html

A B C D

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5

E

Where is the quasar 3C-273?

Thanks to Sloan Digital Sky Survey www.sdss.org/sdss.html

A B C D

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2

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5

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Where is the quasar 3C-273?

Thanks to Sloan Digital Sky Survey www.sdss.org/sdss.html

A B C D

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Markarian 205Quasar

1 billion light-years

NGC 4319Barred spiral galaxy

80 million light-years

What is a quasar?How could it be related to a black hole?

The First Quasar

The Moon lines up with one of the most famous objects in the sky tonight – a quasar known as 3C 273 in the constellation Virgo. But in the early 1960s, there was an even better alignment – the Moon eclipsed the quasar, making a bit of astronomical history.

At the time, 3C 273 was known as a "radio star." Though astronomers could detect it with radio telescopes, they couldn't pinpoint its location well enough to SEE it with optical telescopes.

But that changed the day the Moon passed between the radio star and Earth, blocking its radio signals and allowing astronomers to pinpoint its location. With this information, they could find the object with optical telescopes for the first time.

Even then, they couldn't quite fathom what they saw. Photographic plates showed only an inconspicuous blue star. But when astronomers split the star's light into its individual wavelengths, they found that it was unlike any known star, galaxy, or nebula. Further study eventually revealed that it's billions of light-years away, which means it must be incredibly bright. It's also small, which means its energy source must be incredibly powerful.

Today, astronomers believe that 3C 273 and the thousands of other known quasars are monstrous black holes encircled by disks of gas. As gas spirals into the black hole it's heated, so it glows brightly -- bright enough to see across most of the universe.

Script by Bruce McClure, Copyright 2001 Bruce McClureStarDate Copyright 2001 The University of Texas McDonald Observatory

Compare these two images.

What structure do they have in common?

Hurricane Katrina

Barred spiral galaxy

Compare these two images.

What structure do they have in common?

Hurricane Katrina

Spiral galaxy

Gemini Observatory - AURA

Thought Experiment

What does an object look like if its escape

velocity is the speed of light?

That’s the kind of question that John Michel

asked about stars in 1784. Michel wondered

about a star and light.

He wondered if a star’s escape velocity is the

speed of light, then what is the star’s radius

and mass?

What is a Black Hole?

In Newtonian gravity, the escape velocity from a spherical body depends on its size and mass. As the size decreases and the mass increases, escape velocity goes up. For the escape velocity to equal the speed of light (186,000 miles (299,000 km) per second), nature requires a certain size for a given mass. If an object contracts to this critical size, light can no longer escape from its surface to the distant universe.

This is the essence of a black hole.

A Daring Journey by Dr. Gregory Shields

Credit: Tony and Daphne Hallashttp://hubblesite.org/newscenter/newsdesk/archive/releases/1999/40/image/b

Where are super-massive black holes?

Andromeda Galaxy - a nearby giant galaxy

Where are super-massive black holes?

Bulge DiskForeground stars in our galaxy

Andromeda Galaxy - a nearby giant galaxy

100,000 light-years

Inside the bulge at the core

How observed

Credit: NASA, A. Feild, and R. Van Der Marel (STScI)

http://hubblesite.org/newscenter/newsdesk/archive/releases/2002/18/image/e

How Observed

http://antwrp.gsfc.nasa.gov/apod/ap970516.html

Gas, stars moving toward us

Gas, stars moving away from us

Space Telescope Imaging Spectrograph spectrogram

Image of M84

Area STIS observes

Gas, stars moving across

Spectrogram of gas and stars moving around the core

Black Hole Movies

QuickTime™ and aVideo decompressor

are needed to see this picture.

M87 black holeBlack hole and star close encounter.Tidal forces pull the star apart.

http://heasarc.gsfc.nasa.gov/docs/heasarc/videos/general.htmlhttp://chandra.harvard.edu/resources/animations/blackholes.html

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

http://hubblesite.org/newscenter/newsdesk/archive/releases/2001/03/video/a

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.

http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/26/video/a

Andromeda Galaxy Black HoleMatter Falling into a Black Hole

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.