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Astronomy Rules

Division B + C

Stellar Evolution From Formation to Destruction

This event covers stellar evolution, H-R diagrams, spectra interpretation, binary systems, and related astrophysics concepts.

View Division B Rules | View Division C Rules

Astronomy Practice

Section 1: Concept Atlas

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Interactive study hub - select a topic from the sidebar to explore key concepts.

Topics

    Select a topic from the sidebar to begin.

    Section 2: H-R Diagram Lab

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    Interactive H-R diagram practice - classify stars, compare properties, and trace evolutionary paths.

    Click "Generate Question" to start.

    Stellar Evolution Ordering

    Click "Generate Sequence" to practice ordering evolutionary stages.

    Section 3: Light Curves & Spectra

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    Analyze light curves and spectra - identify patterns and interpret data.

    Light Curve Analysis

    Click "Generate Light Curve" to create a dataset.

    Spectrum Matching

    Click "Generate Spectrum Quiz" to practice spectral classification.

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    Quick Reference

    Spectral Sequence (OBAFGKM)

    O B A F G K M
    • O: 30,000-50,000K (Blue)
    • B: 10,000-30,000K (Blue-white)
    • A: 7,500-10,000K (White)
    • F: 6,000-7,500K (Yellow-white)
    • G: 5,200-6,000K (Yellow - Sun)
    • K: 3,700-5,200K (Orange)
    • M: 2,400-3,700K (Red)

    Mnemonic: Oh Be A Fine Guy/Girl, Kiss Me

    H-R Diagram Regions

    • Main Sequence: Diagonal band (H fusion)
    • Red Giants: Upper right (cool, luminous)
    • Supergiants: Top (extremely luminous)
    • White Dwarfs: Lower left (hot, dim)
    • Instability Strip: Contains Cepheids

    Stefan-Boltzmann Law

    • L ~ R^2 T^4
    • Double radius = 4x luminosity
    • Double temperature = 16x luminosity
    • Same L, cooler T = larger R
    • Same L, hotter T = smaller R

    Magnitude System

    • Lower magnitude = brighter
    • 5 magnitudes = 100x brightness
    • 1 magnitude = ~2.512x brightness
    • Apparent: how bright from Earth
    • Absolute: brightness at 10 parsecs
    • Distance modulus = m - M

    Low-Mass Evolution (Sun-like)

    • 1. Molecular Cloud
    • 2. Protostar
    • 3. Main Sequence (~10 billion yrs)
    • 4. Red Giant (He fusion)
    • 5. Planetary Nebula
    • 6. White Dwarf (cooling)

    High-Mass Evolution (>8 M)

    • 1. Molecular Cloud
    • 2. Protostar (fast)
    • 3. Main Sequence (millions of yrs)
    • 4. Red Supergiant
    • 5. Type II Supernova
    • 6. Neutron Star or Black Hole

    Binary Systems

    • Visual: Both stars resolved
    • Spectroscopic: Doppler shifts
    • Eclipsing: Brightness dips
    • Primary eclipse: brighter star blocked
    • Flat-bottom = total eclipse
    • Period = orbital period

    Light Curve Types

    • Eclipsing Binary: Two dips per period
    • Exoplanet Transit: Small, brief dips
    • Cepheid Variable: Smooth sinusoidal
    • Rotational: Spots cause variation
    • Deeper dip = larger blocking object

    Exoplanet Transits

    • Transit depth ~ (R_planet/R_star)^2
    • Bigger planet = deeper transit
    • Period = time between transits
    • Closer orbit = shorter period
    • Multi-wavelength = atmosphere detection

    Inverse Square Law

    • Flux ~ 1/d^2
    • 2x distance = 1/4 brightness
    • 3x distance = 1/9 brightness
    • Same luminosity, farther = dimmer
    • Used to find distances from known L