Alnair
Alpha Gruis
Scientific overview
Alnair is a subgiant in the constellation Grus (Gruis), lying about 101.01 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 | B7IV |
| Luminosity class | IV |
| Apparent magnitude | 1.73 |
| Absolute magnitude | -0.72 |
| Luminosity (Sun = 1) | 170 |
| Colour index (B−V) | -0.07 |
| Distance | 101.01 ly (30.97 pc) |
Values are real catalogue data; fields without a reliable value are omitted, never estimated.
Precision measurements
Astrometry and astrophysics from SIMBAD
| Parallax | 32.29 ± 0.21 mas | SIMBAD · measured |
| Proper motion (RA) | 126.7 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | -147.5 mas/yr | SIMBAD · measured |
| Radial velocity | 10.9 ± 1.7 km/s | SIMBAD · measured |
| Spectral type | B6V | SIMBAD · catalogued |
| Right ascension (ICRS) | 332.1 deg | SIMBAD · measured |
| Declination (ICRS) | -46.961 deg | SIMBAD · measured |
Full field-level provenance
- Parallax: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · plx_value · 2007A&A...474..653V · direct catalogue measurement · retrieved 2026-07-11
- Proper motion (RA): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · pmra · 2007A&A...474..653V · direct catalogue measurement · retrieved 2026-07-11
- Proper motion (Dec): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · pmdec · 2007A&A...474..653V · direct catalogue measurement · retrieved 2026-07-11
- Radial velocity: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · rvz_radvel · 2006AstL...32..759G · direct catalogue measurement · retrieved 2026-07-11
- Spectral type: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · sp_type · 2006AJ....132..161G · catalogue identifier/value · retrieved 2026-07-11
- Right ascension (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · ra · 2007A&A...474..653V · direct catalogue measurement · retrieved 2026-07-11
- Declination (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · dec · 2007A&A...474..653V · 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 subgiant has begun to evolve off the main sequence, brightening and expanding as core hydrogen fusion ends.
Location in the sky
Knowledge connections
- In constellationGrus
Related stars in Grus
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.