ASTRONOMY 206.2 GENERAL ASTRONOMY II
“Solutions” Sheet
Student Name
Laboratory Exercise 10. The Hertzsprung-Russell Diagram
Purpose. To learn more about individual stars by examining their locations in the Hertzsprung-Russell
(H-R) diagram.
Procedure. See Laboratory Manual.
Equipment.

chart of the Hertzsprung-Russell diagram (attached)
Data.
1. The Nearest Stars
Star
Sun
Proxima Centauri
 Cen A
 Cen B
Barnard’s Star
Wolf 359
BD+36°2147
Sirius A
Sirius B
L726–8A
L726–8B
Ross 154
Ross 248
 Eri
CD–36°15693
Ross 128
L789–6ABC
61 Cyg A
Procyon A
Procyon B
61 Cyg B
BD+59°1915B
Sp. Type
MV
G2 V
M5.5 Ve
G2 V
K1 V
M5 V
M6.5 Ve
M2 V
A1 Vm
DA2
M5.5 Ve
M5.5 Ve
M3.6 Ve
M5.5 Ve
K2 V
M2 V
M4 V
M5 V
K5 V
F5 IV–V
DF
K7 V
M4 V
+4.82
+15.45
+4.34
+5.70
+13.24
+16.57
+10.46
+1.45
+11.33
+15.42
+15.82
+13.00
+14.77
+6.18
+9.76
+13.50
+14.63
+7.49
+2.68
+13.00
+8.33
+11.97
Star
Sp. Type
BD+59°1915A
BD+43°44A
BD+43°44B
G51–15
 Ind
 Cet
L372–58
L725–32
BD+5°1668
Kapteyn’s Star
CD–39°14192
Krüger 60A
Krüger 60B
Ross 614A
BD–12°4523
CD–37°15492
Wolf 424A
van Maanen’s Star
L1159–16
L143–23
CD–25°10553B
BD+68°946
MV
Star
M3.5 V
M2 V
M4 V
M6.5 Ve
K4 Ve
G8 V
M4.5 V
M5.5 Ve
M4 V
M1 VIp
M0 Ve
M3.5 V
M4 Ve
M4 Ve
M4 V
M2 V
M5 Ve
DG
M4.5 Ve
M4
M1.5
M3.5 V
+11.18
+10.33
+13.34
+17.01
+6.89
+5.68
+15.21
+14.25
+11.94
+10.89
+8.71
+11.58
+13.30
+13.05
+11.95
+10.36
+14.89
+14.15
+14.01
+15.60
+13.80
+10.87
LP731–58
CD–46°11540
G208–45
G208–44AB
L145–141
G158–27
BD–15°6290
BD+44°2051A
BD+44°2051B
BD+50°1725
BD+20°2465
CD–49°13515
LP944–20
CD–44°11909
2 Eri A
2 Eri B
2 Eri C
BD+43°4305A
70 Oph A
70 Oph B
Altair
Sp. Type
MV
Star
B0.5 Vp
O9.5 Vep
O9 III
B0.5 Ia
O8 IIIe
A2 Vm
B3 IV
B3 IV
A0 V
A1 Vn
–2.09
–2.43
–5.30
–4.65
–4.16
+0.78
–1.65
–2.00
+1.53
+0.48
3 Ori
4 Ori
5 Ori
6 Ori
 Ori
 Ori
1 Ori
2 Ori
1 Ori
2 Ori
Sp. Type
M6.5 V
M3 V
M6 Ve
M6 Ve
DC:
M5–5.5 V
M5 V
M1 V
M5de
K7 V
M3.5 Ve
M2 V
M9 V
M4 V
K1 V
DA
M4.5 Ve
M4 Ve
K0 V
K4 V
A7 V
MV
+17.32
+11.10
+15.70
+15.12
+13.18
+15.38
+11.80
+10.40
+15.93
+8.16
+10.99
+10.19
+17.00
+12.43
+5.92
+11.01
+12.66
+11.77
+5.67
+7.46
+2.20
2. The Stars in Orion
Star
 Ori
 Ori
 Ori
 Ori
 Ori
 Ori
 Ori
1 Ori A
1 Ori B
1 Ori C
Sp. Type
M2 Ib
B8 Ia
B2 III
O9.5 II
B0 Ia
O9.5 Ib
B1 V + B2e
O7 V
B1 V
O6 V
MV
–5.14
–6.69
–2.72
–4.99
–6.38
–5.26
–3.86
–3.69
–1.46
–4.23
Star
1 Ori D
2 Ori
 Ori
 Ori
 Ori
 Ori
 Ori
 Ori
1 Ori
2 Ori
Sp. Type
F6 V
B2 III
B2 III
K2 II
O9.5 V
B5 III
B0 IV
G8 III–IV
G0 V
B2 Ia
MV
+3.67
–4.25
–4.36
–2.86
–3.96
–2.56
–3.01
+1.33
+4.70
–7.82
Questions to Answer (answers given in the space to the right of the questions)
General
Check List.
main sequence stars (dwarfs) identified on chart √
curved main sequence √
1. Identify from the H-R diagram a star that is a white dwarf
(degenerate star). What is the name of the star in the tables?
2. Identify from the H-R diagram a star that is a red supergiant.
What is the name of the star in the tables?
3. Identify from the H-R diagram a star that is a blue
supergiant. What is the name of the star in the tables?
4. Identify from the H-R diagram a star that is a red giant. What
is the name of the star in the tables?
5. Identify from the H-R diagram the star that is most similar to
the Sun in terms of its luminosity and spectral type (it need not
be identical). What is the name of the star in the tables?
The Nearest Stars
6. Are there any giant or supergiant stars located near the Sun?
7. Identify from the H-R diagram the hottest star in the Sun’s
vicinity. What is the name of the star in the tables?
8. Identify from the H-R diagram the most luminous star in the
Sun’s vicinity. What is the name of the star in the tables?
9. Identify from the H-R diagram the coolest star in the Sun’s
vicinity. What is the name of the star in the tables?
10. Roughly what proportion of stars in the Sun’s vicinity are
similar to the Sun in temperature and luminosity?
11. Are white dwarfs (degenerate stars) a common constituent of
the solar neighbourhood:
a. relative to supergiant stars?
b. relative to M dwarfs?
c. relative to stars like the Sun?
12. What is the approximate mass of the most typical type of star
found in the Sun’s neighbourhood, in solar units?
The Stars in Orion
13. Identify from the H-R diagram the hottest star in Orion.
What is the name of the star in the tables?
14. Identify from the H-R diagram the star in Orion that has the
lowest surface temperature. What is the name of the star in the
tables?
15. For stars in Orion that fall on the main sequence, which one
is the most massive? Identify it by name.
16. Roughly what is the mass of the star identified in question
15?
17. For stars in Orion that fall on the main sequence, which one
is the least massive? Identify it by name.
18. What is the mass of the star identified in question 17?
19. What is the name and spectral type of the intrinsically least
luminous star in Orion?
20. What is the name and spectral type of the intrinsically most
luminous star in Orion?
21. What is the name of the largest star in Orion?
22. What proportion (percentage) of the bright stars in Orion are
over 100 times (5 magnitudes) brighter than the Sun?
23. In terms of the Sun’s radius, how large is the star in question
21? (calculations given below)
Discussion.
Conclusions.