The 42nd Period | STEM Education Hub

🎯 Deliverable — Pick a Format

Ten ID cards plus one master H-R diagram, in either format.

🗂️ Physical Deck

Index cards, one per star, plus a hand-plotted H-R diagram on the blank template. Color each dot to match the star's real color.

💻 Digital Deck

One slide or page per star, plus a spreadsheet scatter chart. Set the luminosity axis to a log scale and reverse the temperature axis so hot stars land on the left.

📈 Blank H-R Diagram Template
🪪 ID Card Template

⭐ The Star Roster

Sixteen real stars with measured data. Choose ten — click a row to add it to your deck. Your ten must include at least one white dwarf and at least three stars off the main sequence. Figuring out which ones those are is part of the job.

0 / 10 selected

Star	Temp (K)	Luminosity (L☉)	Distance	Color	Spectrum shows
Sirius A	9,900	25	8.6 ly	White	Very strong hydrogen lines
Vega	9,600	40	25 ly	White	Very strong hydrogen lines
Spica	22,000	20,000	250 ly	Blue-white	Neutral helium; moderate hydrogen
Procyon A	6,500	7	11.5 ly	Yellow-white	Weakening hydrogen; ionized calcium and metals
Alpha Centauri A	5,800	1.5	4.4 ly	Yellow	Strong ionized calcium; many metal lines
Proxima Centauri	3,000	0.0017	4.2 ly	Red	Titanium oxide bands
Barnard's Star	3,100	0.0035	6 ly	Red	Titanium oxide bands
Arcturus	4,300	170	37 ly	Orange	Strong neutral metals; weak hydrogen
Aldebaran	3,900	440	65 ly	Orange	Strong neutral metals; faint titanium oxide
Betelgeuse	3,500	~100,000	~550 ly	Red-orange	Strong titanium oxide bands
Rigel	12,100	~120,000	~860 ly	Blue-white	Neutral helium; hydrogen
Deneb	8,500	~200,000	~2,600 ly	White	Strong hydrogen lines
Polaris	6,000	~1,300	~430 ly	Yellow-white	Weakening hydrogen; ionized calcium and metals
Sirius B	25,000	0.056	8.6 ly	Blue-white	Very broad hydrogen lines
40 Eridani B	16,500	0.013	16 ly	Blue-white	Broad hydrogen lines
Procyon B	7,700	0.0005	11.5 ly	White	Broad hydrogen lines

Values are rounded; "~" marks stars whose distance, and so luminosity, is less certain. Your selection isn't saved — write your ten down.

🪪 Sample Card — The Sun

Every card needs these fields. The Sun is the model — it doesn't count toward your ten.

The Sun

STELLAR ID · 00

ColorYellow-white

Temperature5,800 K

Luminosity1 L☉

Distance8.3 light-min

Class evidence5,800 K falls in G (5,200–6,000 K); strong ionized calcium and metal lines

H-R regionMain sequence — dead center of the diagram

Size vs. SunThe reference: 1 R☉

Size vs. Sun: compare each star with a main-sequence star at the same temperature. Above the band means bigger; below means smaller. Stretch: estimate the radius with R = √L ÷ (T ÷ 5,800)², using L in Suns.

📋 Content Checklist

Every item below has to show up somewhere in your deck — check them off as you go.

Ten stars chosen from the roster — including at least one white dwarf and at least three stars off the main sequenceEach card: name, color, temperature, luminosity, and distanceEach card: spectral class (letter), with evidence from temperature AND a spectral featureEach card: H-R region, plus whether the star is larger or smaller than the Sun and whyOne master H-R diagram with all ten stars plotted and labeled (and the Sun for reference)A short same-temperature pair analysis: two of your stars with similar temperatures but very different luminosities

📅 Day-by-Day Plan

Day 1

Choose & Classify

Pick your ten stars from the roster. Fill in each card's data and assign a spectral class, citing the temperature range and at least one spectral feature as evidence.

Day 2

Plot & Place

Build the master H-R diagram and plot all ten stars plus the Sun. Name each star's region and decide whether it's larger or smaller than the Sun, adding that to its card.

Day 3

Compare & Submit

Find a same-temperature pair in your deck and write up what their luminosity difference tells you. Trade decks with a partner to check classes and placements, then finalize and submit.

📊 Grading Rubric — 100 pts

A starting point — adjust weights to fit your class before assigning.

Category	Weight	Exemplary	Proficient	Developing	Incomplete
Classification & Evidence	30 pts	All ten stars get the correct spectral class, and every card cites both temperature and a specific spectral feature as evidence.	Nine or ten correct classes; evidence is present but thin or missing on one or two cards.	Several classes wrong, or classes given with no evidence.	Classifications largely missing.
H-R Placement	25 pts	All ten stars plotted accurately on one labeled H-R diagram — temperature decreasing to the right, luminosity on a log scale.	Mostly accurate; one or two stars misplaced or one axis detail wrong.	Axes reversed or not log-scaled, or several stars misplaced.	No master diagram.
Region & Size Reasoning	20 pts	Every card names the correct region and states whether the star is larger or smaller than the Sun, with a reason drawn from its position.	Regions mostly correct; size reasoning present but vague on a few cards.	Regions guessed or size claims unsupported.	Regions and sizes missing.
Same-Temperature Pair	15 pts	Identifies a valid pair and clearly explains that equal temperature plus unequal luminosity means unequal size — with numbers from the cards.	Valid pair and correct conclusion, but the explanation skips a step.	Pair chosen, but the conclusion is about distance or composition instead of size.	No pair analysis.
Presentation	10 pts	Cards are consistent, clean, and easy to scan; the diagram labels every star.	Mostly clear with minor inconsistencies.	Hard to read or inconsistent layout.	Not submitted.

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🔭 Project 4.1.3 · Unit 4 of 6 · Single Semester