ASTR 1050 Exam 3 Results

Scoring

The questions on the exam were applied toward course standards 23–35.  Points were attached to each question for the purposes of grading the questions only; they do not directly translate to a course grade or even to a particular standard.

Answers to the Questions

Multiple choice, fill in the blank, etc.

Question	Answer	Note
1	c	St 23
2	b	St 23
3	c	St 23
4	c	St 24
5	a	St 24
6	b	St 23
7	c	St 26
8	c, d	St 26
9	d	St 24
10	b	St 23
11	c	St 26
12	b, c, d, e	St 25
13	d	St 27
14	Stony-iron: core-mantle boundary; Stony: Mantle; Chondrite: nebula	St 28
15	b	St 27
16	H, He	St 29
17	Core, Radiative zone, Convective Zone, Photosphere, Chromosphere, Corona	St 29
18	b	St 29
19	b	St 31
20	c	St 30
21	a	St 30
22	a	St 30
23	a, c, e	St 30
24	a	St 32
25	c	St 32
26	b	St 33
27	c	St 33
28	b, c, d, e	St 35
29	a	St 35

Short answer

Question 30 The iron cores of asteroids and other Solar system bodies (such as our Earth) cooled very slowly, allowing very large crystals to form.

Question 31 The Kuiper belt is beyond the orbit of Neptune, though its members orbit prograde and roughly in the ecliptic plane.  THe Oort Cloud is more spherically distributed and even farther out.  Their differences in shapes are why the Oort cloud is called a “cloud” and the Kuiper belt a “belt.”

Question 32. An object’s distance in parsecs is equal to the reciprocal of its parallax in arc seconds, so 1/0.08883 pc = 11.26 pc.

Question 33. The spectral classes currently in use, from hottest to coolest surface temperatures, are O B A F G K M.

Question 34. The horizontal axis is temperature (descending); the vertical axis is luminosity; the regions indicated on the plot are (c) supergiants, (d) giants, (e) main sequence, and (f) white dwarfs.

Standards

The criteria for satisfying the standards are summarized in the table below.  The “Formula” column explains how the scores for the questions applied to a standard were combined into a score for that standard.  The “Cutoff” column gives the value the score must match or exceed to satisfy the standard.

Standard	Questions	Criteria
23	1, 2, 3, 6, 10	3 of 5
24	4, 5, 9	2 of 3
25	12	0.6 of 1.0
26	7, 8, 11	2 of 3
27	13, 15, 31	3 of 5
28	14, 30	3 of 4
29	16, 17, 18	3 of 4
30	20, 21, 22, 23	3 of 4
31	19, 32	2 of 2
32	24, 25	2 of 2
33	26, 27, 33	2 of 3
34	34	4 of 6
35	28, 29	1.4 of 2

If you didn’t satisfy a standard

Meet with me to review the standard and arrange for a retest on it.  A retest won’t be the same questions that you had on the exam; it will contain different questions that cover the same material.