121 Tauri
Scientific overview
121 Tauri is a subgiant in the constellation Taurus (Tauri), lying about 552.8 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 | B2.5IV |
| Luminosity class | IV |
| Apparent magnitude | 5.37 |
| Absolute magnitude | -0.78 |
| Luminosity (Sun = 1) | 178 |
| Colour index (B−V) | -0.092 |
| Distance | 552.8 ly (169.49 pc) |
Values are real catalogue data; fields without a reliable value are omitted, never estimated.
Precision measurements
Astrometry and astrophysics from SIMBAD
| Parallax | 5.0758 ± 0.1725 mas | SIMBAD · measured |
| Proper motion (RA) | 11.629 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | -17.6 mas/yr | SIMBAD · measured |
| Radial velocity | 23 ± 0.9 km/s | SIMBAD · measured |
| Spectral type | B2.5IV | SIMBAD · catalogued |
| Right ascension (ICRS) | 83.863 deg | SIMBAD · measured |
| Declination (ICRS) | 24.0396 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 · 1979IAUS...30...57E · 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 constellationTaurus
Related stars in Taurus
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.