20 Ophiuchi
Scientific overview
20 Ophiuchi is a subgiant in the constellation Ophiuchus (Ophiuchi), lying about 104.3 light-years from Earth.
Class F. Yellow-white stars, somewhat hotter and more massive than the Sun. Such stars have surface temperatures around 6,000–7,500 K and appear yellow-white to the eye.
Physical properties
| Spectral type | F7IV |
| Luminosity class | IV |
| Apparent magnitude | 4.64 |
| Absolute magnitude | 2.12 |
| Luminosity (Sun = 1) | 12.405 |
| Colour index (B−V) | 0.478 |
| Distance | 104.3 ly (31.98 pc) |
Values are real catalogue data; fields without a reliable value are omitted, never estimated.
Precision measurements
Astrometry and astrophysics from SIMBAD
| Parallax | 21.4451 ± 0.6347 mas | SIMBAD · measured |
| Proper motion (RA) | 104.1 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | -84.201 mas/yr | SIMBAD · measured |
| Radial velocity | 1.56 ± 0.27 km/s | SIMBAD · measured |
| Spectral type | F7V | SIMBAD · catalogued |
| Right ascension (ICRS) | 252.5 deg | SIMBAD · measured |
| Declination (ICRS) | -10.7831 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 · 2018yCat.1345....0G · direct catalogue measurement · retrieved 2026-07-11
- Spectral type: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · sp_type · 2009ApJS..180..117A · 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 constellationOphiuchus
Related stars in Ophiuchus
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.