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Stellar Spectral Classification - JSON

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"
    ]
  }
]