YAML

Stellar Spectral Classification - YAML

The Stellar Spectral Classification is a classification system developed by Annie Jump Cannon and colleagues at Harvard College Observatory between 1918 and 1924. It categorizes stars into ten types (O, B, A, F, G, K, M, L, T, Y) based on surface temperature, systematically organizing everything from the hottest blue giants to the coolest brown dwarfs. This classification was formally adopted by the precursor to the International Astronomical Union in 1922 and remains the standard classification system used worldwide in astronomy today.

astronomy stars spectral classification Harvard classification surface temperature brown dwarfs

- code: "O"
  slug: "o-type"
  name: "O-type Star"
  description: "The hottest and most massive blue giant stars."
  temperature:
    min_kelvin: 28000
    max_kelvin: 50000
    note: "Some subdwarfs can exceed 100,000K"
  color: "Blue"
  mass_solar:
    min: 16
    max: 150
    typical: 30
  abundance_percent: "<1"
  lifespan: "5-6 million years"
  example_stars:
    - "Zeta Ophiuchi"
    - "Lambda Orionis"
    - "Theta1 Orionis C"
- code: "B"
  slug: "b-type"
  name: "B-type Star"
  description: "Hot blue-white massive stars."
  temperature:
    min_kelvin: 10000
    max_kelvin: 30000
    typical_kelvin: 15000
  color: "Blue-white"
  mass_solar:
    min: 2.1
    max: 16
    typical: 7
  abundance_percent: "0.13"
  lifespan: "~300 million years"
  example_stars:
    - "Rigel"
    - "Spica"
    - "Regulus"
- code: "A"
  slug: "a-type"
  name: "A-type Star"
  description: "White stars with the strongest hydrogen lines."
  temperature:
    min_kelvin: 7400
    max_kelvin: 10000
    typical_kelvin: 8500
  color: "White"
  mass_solar:
    min: 1.4
    max: 2.1
    typical: 1.7
  abundance_percent: "0.625"
  lifespan: "1-2 billion years"
  example_stars:
    - "Sirius A"
    - "Vega"
    - "Altair"
    - "Fomalhaut"
- code: "F"
  slug: "f-type"
  name: "F-type Star"
  description: "Yellow-white stars with intermediate temperature."
  temperature:
    min_kelvin: 6000
    max_kelvin: 7500
    typical_kelvin: 6700
  color: "Yellow-white"
  mass_solar:
    min: 1
    max: 1.4
    typical: 1.2
  abundance_percent: "3"
  lifespan: "4-8 billion years"
  example_stars:
    - "Procyon A"
    - "Polaris Aa"
    - "Canopus"
- code: "G"
  slug: "g-type"
  name: "G-type Star (Yellow Dwarf)"
  description: "Yellow main-sequence stars like our Sun."
  temperature:
    min_kelvin: 5200
    max_kelvin: 6000
    typical_kelvin: 5778
  color: "Yellow"
  mass_solar:
    min: 0.8
    max: 1.15
    typical: 1
  abundance_percent: "7.5"
  lifespan: "~10 billion years (for solar mass)"
  example_stars:
    - "Sun"
    - "Alpha Centauri A"
    - "Tau Ceti"
    - "51 Pegasi"
- code: "K"
  slug: "k-type"
  name: "K-type Star (Orange Dwarf)"
  description: "Orange main-sequence stars cooler than the Sun."
  temperature:
    min_kelvin: 3900
    max_kelvin: 5200
    typical_kelvin: 4500
  color: "Orange"
  mass_solar:
    min: 0.5
    max: 0.8
    typical: 0.65
  abundance_percent: "12"
  lifespan: "17-70 billion years"
  example_stars:
    - "Epsilon Eridani"
    - "Alpha Centauri B"
    - "61 Cygni A"
- code: "M"
  slug: "m-type"
  name: "M-type Star (Red Dwarf)"
  description: "The most common and longest-lived red main-sequence stars."
  temperature:
    min_kelvin: 2400
    max_kelvin: 3900
    typical_kelvin: 3200
  color: "Red"
  mass_solar:
    min: 0.08
    max: 0.5
    typical: 0.3
  abundance_percent: "75"
  lifespan: "1-10 trillion years"
  example_stars:
    - "Proxima Centauri"
    - "Barnard's Star"
    - "TRAPPIST-1"
    - "Wolf 359"
- code: "L"
  slug: "l-type"
  name: "L-type Dwarf"
  description: "Cool brown dwarfs with water and metal hydride absorption."
  temperature:
    min_kelvin: 1300
    max_kelvin: 2500
    typical_kelvin: 1900
  color: "Dark red"
  mass_jupiter:
    min: 13
    max: 65
    typical: 30
  object_type: "Brown dwarf or cool star"
  example_stars:
    - "2MASS J0523-1403"
    - "DENIS-P J1228.2-1547"
- code: "T"
  slug: "t-type"
  name: "T-type Dwarf"
  description: "Cool brown dwarfs with methane absorption bands."
  temperature:
    min_kelvin: 600
    max_kelvin: 1500
    typical_kelvin: 1000
  color: "Magenta/Black"
  mass_jupiter:
    min: 13
    max: 80
    typical: 50
  object_type: "Brown dwarf"
  example_stars:
    - "Gliese 570 D"
    - "WISE J0350-5658"
    - "2MASS J0559-1404"
- code: "Y"
  slug: "y-type"
  name: "Y-type Dwarf"
  description: "The coldest brown dwarfs with ammonia absorption features."
  temperature:
    min_kelvin: 200
    max_kelvin: 600
    typical_kelvin: 400
  color: "Black (detectable only in infrared)"
  mass_jupiter:
    min: 13
    max: 80
    typical: 50
  object_type: "Brown dwarf"
  example_stars:
    - "WISE J0855-0714"
    - "WISE J1828+2650"
    - "WISE J1738+2732"