High Energy Groove

# X-Ray Binary 

**Level:** Grades 7-9

**National Science Education Standards:**
(http://www.nap.edu/readingroom/books/nses/html/index.html)

## Physical Science: Motion and Forces

-The motion of an object can be described by its position, direction of
motion, and speed. That motion can be measured and represented on a
graph. (grades 6-8)

## - Gravitation is a universal force that each mass exerts on any other mass. The strength of the gravitational attractive force between two masses is proportional to the masses and inversely proportional to the square of the distance between them. (grades 9-12)

## Earth and Space Science: Earth in the Solar System

\- Gravity is the force that keeps planets in orbit around the sun and
governs the rest of the motion in the solar system. Gravity alone holds
us to the earth\'s surface and explains the phenomena of the tides.
(grades 6-8)

-Early in the history of the universe, matter, primarily the light atoms
hydrogen and helium, clumped together by gravitational attraction to
form countless trillions of stars. Billions of galaxies, each of which
is a gravitationally bound cluster of billions of stars, now form most
of the visible mass in the universe. (grades 9-12)

**Objective:**

Students will identify the structure of a black hole.

Students will describe the relationship between the black hole and its
companion star.

**Enduring Understanding:**

Black holes have an infinite density (singularity). If a black hole is
close enough to a normal star that material is being pulled from the
normal star, they are called x-ray binaries. The material pulled from
the companion star creates an accretion disk around the black hole.

**Essential Questions:**

What is a black hole? What is the relationship between the black hole
and it's companion star?

**Materials (per group of three):**

10 screw eyes

Masking tape

Measuring tape

Triple beam balance

1 plastic 12 oz. clear disposable cup

4 Sturdy 8-12 inch paper or styrofoam disposable plates

Ball of yarn (yarn of various colors has a more dramatic effect)

**Vocabulary:** Black Hole, Companion Star, Accretion Disk, Event
Horizon, Singularity, X-Ray Binary

**Warm up:**

Students should read the article "How Black Holes Work," by Craig C.
Freudenrich, Ph.D.
(http://howstuffworks.lycoszone.com/black-hole.htm/printable) Have
students to pick out one interesting statement from the article to share
with the class and tell why they think it is interesting.

**Procedure:**

-Divide students into groups of three.

*Students will complete the following within their groups.*

-Trace the larger end of the cup onto the center of four plates.
Puncture the middle of the plate with the scissors and cut out the
circles just to the inside of the line, creating a doughnut shape. The
first plate may be used as a template for the other plates.

-Puncture the bottom of the cup from the inside with a screw eye
creating a small hole. The hole should be large enough for the yarn to
pull through.

-Place the four plates on top of each other and tape them together to
keep from sliding. Secure the cup into the middle of the plates. The cup
should be flush with the surface of the top plate.

-Place the screw eyes in the plates in a spiral fashion starting just
outside the cup and working towards the outer rim of the plates. (see
template) If the screw eyes puncture through the plates, cover the tips
with masking tape.

-Wrap the end piece of the yarn with 1 inch of masking tape to create a
point. Thus, making it easier to thread through the screw eyes.

-Thread the yarn through the screw eyes starting with the outside rim
and working towards the cup. Continue to thread through the hole in the
bottom of the cup until the string is hanging a few inches below the
bottom of the cup.

**Procedure continued:**

-The ball of yarn will represent the COMPANION STAR. One person will
hold the companion star. \*\*Measure the circumference and the mass of
the companion star and record in the chart.

-The cup will represent the BLACK HOLE and the string surrounding the
hole will represent the ACCRETION DISK. The bottom of the cup represents
the EVENT HORIZON. The second person will hold the black hole about
10-12 inches away from the companion star.

-The third person will slowly pull the yarn from bottom of the cup.
Thus, showing how material is pulled from the companion star into the
black hole.

-Once the material is pulled into the black hole it becomes a part of
the total mass of the black hole. The material may no longer return to
the companion star. Over time the companion star will continually
decrease in size.

-Allow students time to complete the chart and explore with the model.

-Check for understanding by discussing the key points of the model: the
structure, vocabulary, what happens as the model is in action, the
changes in the mass and size of both the companion star and the black
hole, larger masses distort

space time (see diagram below)

![](media/image1.png){width="5.9944444444444445in"
height="3.8958333333333335in"}

**Assessment:** Review the activity sheet as a class to ensure
understanding.

**Finished Model:**

![](media/image2.png){width="2.8229166666666665in"
height="1.4840277777777777in"}

![](media/image3.png){width="3.5944444444444446in"
height="1.6243055555555554in"}

**Resources:**

<http://universe.gsfc.nasa.gov/press/cw02_14.html>

<http://universe.gsfc.nasa.gov/press/cw02_12.html>

<http://rxte.gsfc.nasa.gov/docs/xte/learning_center/discover_0200.html>

<http://saturn.sron.nl/~erikk/v4641sgr/v4641sgr.html>

<http://worldbook.bigchalk.com/062594.htm>

Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

# X-Ray Binary 

Directions for Model

**Procedure:**

-Trace the larger end of the cup onto the center of four plates.
Puncture the middle of the plate with the scissors and cut out the
circles just to the inside of the line, creating a doughnut shape. The
first plate may be used as a template for the other plates.

-Puncture the bottom of the cup from the inside with a screw eye
creating a small hole. The hole should be large enough for the yarn to
pull through.

-Place the four plates on top of each other and tape them together to
keep from sliding. Secure the cup into the middle of the plates. The cup
should be flush with the surface of the top plate.

-Place the screw eyes in the plates in a spiral fashion starting just
outside the cup and working towards the outer rim of the plates. (see
template) If the screw eyes puncture through the plates, cover the tips
with masking tape.

-Wrap the end piece of the yarn with 1 inch of masking tape to create a
point. Thus, making it easier to thread through the screw eyes.

-Thread the yarn through the screw eyes starting with the outside rim
and working towards the cup. Continue to thread through the hole in the
bottom of the cup until the string is hanging a few inches below the
bottom of the cup.

-The ball of yarn will represent the COMPANION STAR. One person will
hold the companion star. \*\*Measure the circumference and the mass of
the companion star and record in the chart.

-The cup will represent the BLACK HOLE and the string surrounding the
hole will represent the ACCRETION DISK. The bottom of the cup represents
the EVENT HORIZON. The second person will hold the black hole about
10-12 inches away from the companion star.

-The third person will slowly pull the yarn from bottom of the cup.
Thus, showing how material is pulled from the companion star into the
black hole.

-Once the material is pulled into the black hole it becomes a part of
the total mass of the black hole. The material may no longer return to
the companion star. Over time the companion star will continually
decrease in size.

-Pull the yarn slowly for 5 seconds and record the circumference of the
companion star and mass of both the companion star and the material
added to the black hole. Repeat three times. Complete the activity
sheet.

Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

# X-Ray Binary 

Activity Sheet

Label the diagram.

![](media/image4.png){width="5.999305555555556in"
height="2.1506944444444445in"}

1.  What happens to the mass of the black hole as it takes in material
    from the companion star?

2.  Why is there an accretion disk surrounding the black hole?

3.  What force causes the material to be pulled towards the singularity?

4.  What makes it possible for us to "see" a black hole?

5.  At what point can material no longer escape from the black hole?

6\. At what point can material no longer escape from the black hole?

Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

### X-Ray Binary Data

Complete Data Chart:

+-----------------+----------------+----------------+----------------+
|                 | Circumference  | Mass of        | Mass of        |
|                 |                |                | Material added |
|                 | Of Companion   | Companion Star | to Black Hole  |
|                 | Star           |                |                |
+-----------------+----------------+----------------+----------------+
| 0 seconds       |                |                |                |
+-----------------+----------------+----------------+----------------+
| 5 seconds       |                |                |                |
+-----------------+----------------+----------------+----------------+
| 10 seconds      |                |                |                |
+-----------------+----------------+----------------+----------------+
| 15 seconds      |                |                |                |
+-----------------+----------------+----------------+----------------+
| 20 seconds      |                |                |                |
+-----------------+----------------+----------------+----------------+

Graph Data:

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Spiral Template