HR 4817
Scientific overview
HR 4817 is a blue giant in the constellation Centaurus (Centauri), lying about 364.8 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 type | B8II/III |
| Luminosity class | III |
| Apparent magnitude | 4.63 |
| Absolute magnitude | -0.61 |
| Luminosity (Sun = 1) | 153 |
| Colour index (B−V) | -0.082 |
| Distance | 364.8 ly (111.86 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 6153047015281588864
| Parallax | 9.738 ± 0.2028 mas | SIMBAD · measured |
| Distance | 102.3 pc | Gaia · estimated |
| Proper motion (RA) | -41.544 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | -26.757 mas/yr | SIMBAD · measured |
| Radial velocity | 15.1 km/s | SIMBAD · measured |
| Spectral type | B8II/III | SIMBAD · catalogued |
| Right ascension (ICRS) | 190 deg | SIMBAD · measured |
| Declination (ICRS) | -39.9873 deg | SIMBAD · 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 6153047015281588864 · 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 · 2023ApJS..266...41P · direct catalogue measurement · retrieved 2026-07-11
- Spectral type: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · sp_type · 1982MSS...C03....0H · 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
Knowledge connections
- In constellationCentaurus
Related stars in Centaurus
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.