ASTRONOMY 5

THIRD HOUR SESSION “G”

NAME

KEY-G

 

 

 

 

 

ACTIVITY:  The Hertzsprung-Russell Diagram

DATE

 

ID#

 

Note: Use your SC001/SC002 star charts and Starry Nights software as needed.

 

1.   Label the horizontal and and vertical axes, and indicate the units on the scales.

2.   At the bottom of the chart, write the 7-letter spectral type sequence.

3.   On the HR diagram on the next page, indicate the locations of the following:
— Main Sequence        — Giants       Supergiants        — White Dwarfs

4.   What spectral type is plotted on the far _______RIGHT_______________ of the HR diagram? What is the spectral type of the Sun?

M

G2

5.   What luminosity class (or classes) includes ________Supergiant___ stars?

I

6.   Stars with extremely ___HIGH LUMINOSITY______ are plotted where on the HR diagram (top/bottom/left/right)?

Top

7.   What is the name of the bright star found near RA= __13h 47m _____ and DEC= ____+49°______? What constellation is it in?

Alkaid

Ursa Major

8.   Using Starry Nights, what is the temperature and luminosity of the star from question #7?

11235 K

212 Lsun

9.   Plot the star in question #7 onto your HR diagram. What kind of star (giant, supergiant, etc.) is it? Using the internet reference specified by your instructor, what is the star’s spectral type (including luminosity class)?

MAIN SEQUENCE

B3 V

 


10. Where are on HR diagram (top-left, bottom-right, etc) are stars with the ___largest_ radii plotted?

Top-Right

11. Two stars, spectral types ___A5V_____ and ____K5V_____ are both in a star cluster, and are therefore about the same distance from us. Which will look brighter to us on the Earth? Which will look redder?

A5V

K5V

12. Two stars are in the same cluster as question #11. One is spectral type _____K5V____ and the other is ___K5II______. Which will look brighter to us?

K5II

Main Sequence

(Q3)

 

WDs

(Q3)

 

Giants

(Q3)

 

Supergiants

(Q3)

 

Luminosity (solar units)

(Q1)

 

TEMPERATURE (Q1)

O    B     A     F     G   K    M (Q2)


Intro lecture:

 

 

Fill ins and question explanations

 

4.   Left           Right

5.   Supergiant         Giant              Main Sequence

      (answers: I, II-IV, V)

6.   High Temperature        High Luminosity     Low Temperature              Low Luminosity

7-9.     Useful selections. I fully support using Wikipedia.

 

Star

Temperature
(Starry Nights)

Luminosity (Starry Nights)

RA

Dec

SC (Wikipedia)

Capella

5419 K

420 L

5h 17m

46°

K0III

Alkaid

11235 K

212 L

13h 47m

49°

B3V

Phecda

8666 K

89 L

11h 53m

54°

A0V

Arcturus

4106 K

1196 L

14h 15m

19°

K0III

 

10. Largest                Smallest

11. Any two spectral types, but both are main sequence stars, i.e., O V +G V

12. Two stars of same spectral type (A-M), but different luminosity classes, i.e., K V and K I