Sigma Aquarii
Scientific overview
Sigma Aquarii is a subgiant in the constellation Aquarius (Aquarii), lying about 289.66 light-years from Earth.
Class A. White stars with strong hydrogen lines. Many of the brightest stars in the sky are class A. Such stars have surface temperatures around 7,500–10,000 K and appear white to the eye.
Physical properties
| Spectral type | A0IVs |
| Luminosity class | IV |
| Apparent magnitude | 4.82 |
| Absolute magnitude | 0.08 |
| Luminosity (Sun = 1) | 81.059 |
| Colour index (B−V) | -0.053 |
| Distance | 289.66 ly (88.81 pc) |
Values are real catalogue data; fields without a reliable value are omitted, never estimated.
Precision measurements
Astrometry and astrophysics from SIMBAD
| Parallax | 15.8247 ± 0.4146 mas | SIMBAD · measured |
| Proper motion (RA) | -4.095 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | -38.019 mas/yr | SIMBAD · measured |
| Radial velocity | 11.7 ± 0.6 km/s | SIMBAD · measured |
| Spectral type | A0IVs | SIMBAD · catalogued |
| Right ascension (ICRS) | 337.7 deg | SIMBAD · measured |
| Declination (ICRS) | -10.6779 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
- 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 · 2006AstL...32..759G · 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 subgiant has begun to evolve off the main sequence, brightening and expanding as core hydrogen fusion ends.
Location in the sky
Knowledge connections
- In constellationAquarius
Related stars in Aquarius
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.