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Blue giant · Cassiopeia

23 Cassiopeiae

Knowledge graph23 CasHR 208HD 4382HIP 3721

Scientific overview

23 Cassiopeiae is a blue giant in the constellation Cassiopeia (Cassiopeiae), lying about 771.1 light-years from Earth.

Class B. Hot, blue-white stars. Massive and luminous, they often light up the regions where they form. Such stars have surface temperatures around 10,000–30,000 K and appear blue-white to the eye.

Physical properties

Spectral typeB8III
Luminosity classIII
Apparent magnitude5.42
Absolute magnitude-1.45
Luminosity (Sun = 1)331
Colour index (B−V)-0.066
Distance771.1 ly (236.41 pc)

Values are real catalogue data; fields without a reliable value are omitted, never estimated.

Precision measurements

Astrometry and astrophysics from SIMBAD and Gaia DR3 · Gaia DR3 539042726640996352

Parallax4.1495 ± 0.0574 masSIMBAD · measured
Distance238.7 pcGaia · estimated
Proper motion (RA)15.153 mas/yrSIMBAD · measured
Proper motion (Dec)-7.549 mas/yrSIMBAD · measured
Radial velocity-3.1 ± 0.9 km/sSIMBAD · measured
Spectral typeB8IIISIMBAD · catalogued
Right ascension (ICRS)11.9419 degSIMBAD · measured
Declination (ICRS)74.8476 degSIMBAD · measured
Full field-level provenance
  • Parallax: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · plx_value · 2020yCat.1350....0G · direct catalogue measurement · retrieved 2026-07-11
  • Distance: ESA Gaia astrometric survey · Gaia EDR3 · Bailer-Jones (2021) · external.gaiaedr3_distance · r_med_geo · row 539042726640996352 · Bayesian estimate · retrieved 2026-07-11
  • Proper motion (RA): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · pmra · 2020yCat.1350....0G · direct catalogue measurement · retrieved 2026-07-11
  • Proper motion (Dec): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · pmdec · 2020yCat.1350....0G · direct catalogue measurement · retrieved 2026-07-11
  • Radial velocity: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · rvz_radvel · 1953GCRV..C......0W · direct catalogue measurement · retrieved 2026-07-11
  • Spectral type: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · sp_type · catalogue identifier/value · retrieved 2026-07-11
  • Right ascension (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · ra · 2020yCat.1350....0G · direct catalogue measurement · retrieved 2026-07-11
  • Declination (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · dec · 2020yCat.1350....0G · direct catalogue measurement · retrieved 2026-07-11

measured = direct catalogue value · estimated = Bayesian inference (Bailer-Jones distance) · modeled = model output (Gaia GSP-Phot). Fields a source did not provide are omitted, never invented.

Evolution

A blue giant is a hot, massive, highly luminous star that has evolved off the main sequence. Such stars are short-lived on cosmic timescales.

Location in the sky

Constellation
Cassiopeia
Hemisphere
Northern
Best seen
Autumn (N. evening sky)
RA / Dec
0.7961h / 74.8476°

Knowledge connections

  • In constellationCassiopeia (constellation)

Sources

The primary and reference sources this topic draws on.

  • HYG DatabaseHYG Database (Hipparcos + Yale Bright Star + Gliese), by D. Nash / astronexus

    Aggregated, openly-licensed star catalogue combining Hipparcos, the Yale Bright Star Catalogue, and the Gliese Catalogue of Nearby Stars.

  • HipparcosESA Hipparcos space astrometry mission

    High-precision parallax, magnitude, and position for ~118,000 stars.