{
  "family": "multiple-stars",
  "name": "Double & Multiple Stars",
  "generatedAt": "2026-10-14",
  "count": 4,
  "objects": [
    {
      "id": "star:albireo",
      "slug": "albireo",
      "canonicalName": "Albireo (Beta Cygni A & B)",
      "aliases": [
        "β Cygni",
        "HD 183912 / HD 183914",
        "HIP 95947"
      ],
      "constellation": "Cygnus",
      "path": "/objects/multiple-stars/albireo/",
      "coordinates": {
        "raHours": 19.512028,
        "raSexagesimal": "19h 30m 43.29s",
        "decDegrees": 27.959681,
        "decSexagesimal": "+27° 57′ 34.8″",
        "epoch": "J2000.0",
        "sourceId": "src:hipparcos-new"
      },
      "classification": {
        "primaryClass": "Wide visual double star (K3 II amber giant + B8 V blue-green dwarf)",
        "spectralType": "K3 II + B8:p + B8 Ve"
      },
      "measurements": [
        {
          "id": "star:albireo:vmag-a",
          "entityId": "star:albireo",
          "property": "apparent_magnitude_v",
          "label": "Apparent magnitude (Albireo A)",
          "value": 3.08,
          "unit": "mag",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.02
          },
          "method": "Johnson UBV photometry (Albireo B = 5.11 mag)",
          "sourceId": "src:hipparcos-new",
          "datasetVersion": "2007 New Reduction",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:albireo:ang-sep",
          "entityId": "star:albireo",
          "property": "angular_size_arcmin",
          "label": "Visual A–B angular separation",
          "value": 0.577,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.002
          },
          "method": "Washington Double Star Catalog astrometry (34.6 arcseconds at PA 54°)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:albireo:dist-b",
          "entityId": "star:albireo",
          "property": "distance_pc",
          "label": "Distance to Albireo B (Gaia DR3)",
          "value": 119.4,
          "unit": "pc",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 2.2
          },
          "method": "Gaia DR3 parallax of β² Cygni (8.37 ± 0.15 mas)",
          "epoch": "J2016.0",
          "sourceId": "src:gaia-dr3",
          "datasetVersion": "DR3 (2022-06-13)",
          "qualityStatus": "definitive",
          "disagreementNote": "Albireo A is an unresolved close triple (Aa+Ac+Ad) whose photocenter motion complicates single-star parallax fits (~100–133 pc), while Gaia DR3 shows Albireo A and B have significantly different proper motions, fueling ongoing debate over whether they are an unbound optical double or an extremely wide (>100,000 yr) perturbed system."
        },
        {
          "id": "star:albireo:teff-a",
          "entityId": "star:albireo",
          "property": "effective_temperature_k",
          "label": "Effective temperature (Albireo Aa vs B)",
          "value": 4270,
          "unit": "K",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 60
          },
          "method": "K3 II giant spectroscopy (Albireo B = 13,200 ± 300 K)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:gaia-dr3",
        "src:hipparcos-new",
        "src:iau-star-names"
      ]
    },
    {
      "id": "star:mizar-and-alcor",
      "slug": "mizar-and-alcor",
      "canonicalName": "Mizar & Alcor (Zeta & 80 Ursae Majoris)",
      "aliases": [
        "ζ Ursae Majoris",
        "80 Ursae Majoris",
        "Horse and Rider",
        "HIP 65378"
      ],
      "constellation": "Ursa Major",
      "path": "/objects/multiple-stars/mizar-and-alcor/",
      "coordinates": {
        "raHours": 13.398728,
        "raSexagesimal": "13h 23m 55.54s",
        "decDegrees": 54.925361,
        "decSexagesimal": "+54° 55′ 31.3″",
        "epoch": "J2000.0",
        "sourceId": "src:hipparcos-new"
      },
      "classification": {
        "primaryClass": "Sextuple A-type stellar system (first telescopic & first spectroscopic binary)",
        "spectralType": "A2 V + A2 V + A5 Vm (Ursa Major Moving Group)"
      },
      "measurements": [
        {
          "id": "star:mizar-and-alcor:vmag",
          "entityId": "star:mizar-and-alcor",
          "property": "apparent_magnitude_v",
          "label": "Apparent magnitude (Mizar A+B combined)",
          "value": 2.04,
          "unit": "mag",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.01
          },
          "method": "Johnson UBV photometry (Mizar A = 2.23, Mizar B = 3.88, Alcor = 3.99)",
          "sourceId": "src:hipparcos-new",
          "datasetVersion": "2007 New Reduction",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:mizar-and-alcor:dist-pc",
          "entityId": "star:mizar-and-alcor",
          "property": "distance_pc",
          "label": "Distance (NPOI interferometric orbital parallax of Mizar A)",
          "value": 25.4,
          "unit": "pc",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.2
          },
          "method": "Navy Precision Optical Interferometer (NPOI) resolved orbit (82.8 ± 0.6 ly)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:mizar-and-alcor:ang-sep-ab",
          "entityId": "star:mizar-and-alcor",
          "property": "angular_size_arcmin",
          "label": "Mizar A–B telescopic separation",
          "value": 0.24,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.002
          },
          "method": "Astrometric separation 14.4 arcseconds at PA 153° (Alcor is 11.8 arcminutes away)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:mizar-and-alcor:period-aa",
          "entityId": "star:mizar-and-alcor",
          "property": "orbital_period_days",
          "label": "Mizar Aa–Ab spectroscopic orbital period",
          "value": 20.53835,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.00005
          },
          "method": "Double-lined spectroscopic + NPOI interferometric orbit (e = 0.537)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:hipparcos-new",
        "src:gaia-dr3",
        "src:iau-star-names"
      ]
    },
    {
      "id": "star:epsilon-lyrae",
      "slug": "epsilon-lyrae",
      "canonicalName": "Epsilon Lyrae (ε¹ & ε² Lyrae — The Double Double)",
      "aliases": [
        "ε Lyrae",
        "Double Double",
        "4 & 5 Lyrae",
        "HIP 91919 / HIP 91926"
      ],
      "constellation": "Lyra",
      "path": "/objects/multiple-stars/epsilon-lyrae/",
      "coordinates": {
        "raHours": 18.739306,
        "raSexagesimal": "18h 44m 20.30s",
        "decDegrees": 39.669694,
        "decSexagesimal": "+39° 40′ 12.4″",
        "epoch": "J2000.0",
        "sourceId": "src:gaia-dr3"
      },
      "classification": {
        "primaryClass": "Hierarchical quadruple (and quintuple) A/F-type multiple star system",
        "spectralType": "A3 V + F0 V & A6 Vn + A7 Vn"
      },
      "measurements": [
        {
          "id": "star:epsilon-lyrae:vmag",
          "entityId": "star:epsilon-lyrae",
          "property": "apparent_magnitude_v",
          "label": "Combined apparent visual magnitude",
          "value": 3.82,
          "unit": "mag",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.02
          },
          "method": "Integrated photometry (ε¹ = 4.67 mag, ε² = 4.59 mag)",
          "sourceId": "src:hipparcos-new",
          "datasetVersion": "2007 New Reduction",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:epsilon-lyrae:dist-pc",
          "entityId": "star:epsilon-lyrae",
          "property": "distance_pc",
          "label": "System distance (Gaia DR3)",
          "value": 49.1,
          "unit": "pc",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.4
          },
          "method": "Gaia DR3 astrometric parallax of components (~20.37 mas, 160.1 ly)",
          "epoch": "J2016.0",
          "sourceId": "src:gaia-dr3",
          "datasetVersion": "DR3 (2022-06-13)",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:epsilon-lyrae:ang-sep-wide",
          "entityId": "star:epsilon-lyrae",
          "property": "angular_size_arcmin",
          "label": "Wide ε¹–ε² angular separation",
          "value": 3.47,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.01
          },
          "method": "Astrometric separation 208.2 arcseconds (tight pairs are 2.3″ and 2.4″)",
          "sourceId": "src:gaia-dr3",
          "datasetVersion": "DR3 (2022-06-13)",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:epsilon-lyrae:teff",
          "entityId": "star:epsilon-lyrae",
          "property": "effective_temperature_k",
          "label": "Component effective temperatures",
          "value": 8200,
          "unit": "K",
          "uncertainty": {
            "kind": "range",
            "min": 7300,
            "max": 8500
          },
          "method": "A3–F0 main-sequence spectroscopy across four visual components",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "high-confidence"
        }
      ],
      "sources": [
        "src:gaia-dr3",
        "src:hipparcos-new",
        "src:simbad-cds"
      ]
    },
    {
      "id": "star:castor",
      "slug": "castor",
      "canonicalName": "Castor (Alpha Geminorum)",
      "aliases": [
        "α Geminorum",
        "HD 60179",
        "HIP 36850",
        "66 Geminorum"
      ],
      "constellation": "Gemini",
      "path": "/objects/multiple-stars/castor/",
      "coordinates": {
        "raHours": 7.576669,
        "raSexagesimal": "07h 34m 35.86s",
        "decDegrees": 31.888278,
        "decSexagesimal": "+31° 53′ 17.8″",
        "epoch": "J2000.0",
        "sourceId": "src:hipparcos-new"
      },
      "classification": {
        "primaryClass": "Hierarchical sextuple star system (three spectroscopic binaries)",
        "spectralType": "A1 V + A2 Vm + M1 Ve"
      },
      "measurements": [
        {
          "id": "star:castor:vmag",
          "entityId": "star:castor",
          "property": "apparent_magnitude_v",
          "label": "Combined apparent visual magnitude (V)",
          "value": 1.58,
          "unit": "mag",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.01
          },
          "method": "Johnson UBV photometry (Castor A = 1.93, B = 2.97, C = 9.27)",
          "sourceId": "src:hipparcos-new",
          "datasetVersion": "2007 New Reduction",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:castor:plx",
          "entityId": "star:castor",
          "property": "parallax_mas",
          "label": "Trigonometric parallax",
          "value": 64.12,
          "unit": "mas",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 3.75
          },
          "method": "Hipparcos + visual binary orbital parallax (~15.6 pc / 50.8 ly)",
          "epoch": "J2000.0",
          "sourceId": "src:hipparcos-new",
          "datasetVersion": "2007 New Reduction",
          "qualityStatus": "high-confidence"
        },
        {
          "id": "star:castor:ang-sep",
          "entityId": "star:castor",
          "property": "angular_size_arcmin",
          "label": "Castor A–B angular separation (2026 epoch)",
          "value": 0.093,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.002
          },
          "method": "Visual binary ephemeris (~5.6 arcseconds at PA ~51°; widening toward apastron)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "definitive"
        },
        {
          "id": "star:castor:period-ab",
          "entityId": "star:castor",
          "property": "orbital_period_days",
          "label": "Castor A–B visual orbital period",
          "value": 162600,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 1800
          },
          "method": "Keplerian visual orbit (~445 years, e = 0.343)",
          "sourceId": "src:simbad-cds",
          "datasetVersion": "2026-10 release",
          "qualityStatus": "high-confidence"
        }
      ],
      "sources": [
        "src:hipparcos-new",
        "src:iau-star-names",
        "src:simbad-cds"
      ]
    }
  ]
}