Helvetios
51 Pegasi
Scientific overview
Helvetios is a yellow dwarf in the constellation Pegasus (Pegasi), lying about 50.91 light-years from Earth.
Class G. Yellow stars like the Sun. On the main sequence they steadily fuse hydrogen into helium. Such stars have surface temperatures around 5,200–6,000 K and appear yellow to the eye.
Physical properties
| Spectral type | G5V |
| Luminosity class | V |
| Apparent magnitude | 5.45 |
| Absolute magnitude | 4.48 |
| Luminosity (Sun = 1) | 1.402 |
| Colour index (B−V) | 0.666 |
| Distance | 50.91 ly (15.61 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 2835207319109249920
| Parallax | 64.4048 ± 0.0771 mas | SIMBAD · measured |
| Distance | 15.5147 pc | Gaia · estimated |
| Proper motion (RA) | 207.3 mas/yr | SIMBAD · measured |
| Proper motion (Dec) | 61.164 mas/yr | SIMBAD · measured |
| Radial velocity | -33.165 ± 6.000e-4 km/s | SIMBAD · measured |
| Spectral type | G2IV | SIMBAD · catalogued |
| Effective temperature | 5662.5 K | Gaia · modeled |
| Radius | 1.2148 R_sun | Gaia · modeled |
| Surface gravity (log g) | 4.3077 log(cm/s^2) | Gaia · modeled |
| Metallicity [M/H] | -0.187 dex | Gaia · modeled |
| Right ascension (ICRS) | 344.4 deg | SIMBAD · measured |
| Declination (ICRS) | 20.7688 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 2835207319109249920 · 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 · 2018A&A...616A...7S · direct catalogue measurement · retrieved 2026-07-11
- Spectral type: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · sp_type · 1989ApJS...71..245K · catalogue identifier/value · retrieved 2026-07-11
- Effective temperature: ESA Gaia astrometric survey · Gaia DR3 · gaiadr3.astrophysical_parameters · teff_gspphot · row 2835207319109249920 · model output · retrieved 2026-07-11
- Radius: ESA Gaia astrometric survey · Gaia DR3 · gaiadr3.astrophysical_parameters · radius_gspphot · row 2835207319109249920 · model output · retrieved 2026-07-11
- Surface gravity (log g): ESA Gaia astrometric survey · Gaia DR3 · gaiadr3.astrophysical_parameters · logg_gspphot · row 2835207319109249920 · model output · retrieved 2026-07-11
- Metallicity [M/H]: ESA Gaia astrometric survey · Gaia DR3 · gaiadr3.astrophysical_parameters · mh_gspphot · row 2835207319109249920 · model output · 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 yellow dwarf is a G-type main-sequence star like the Sun. After about ten billion years it will swell into a red giant and finally leave behind a white dwarf.
Location in the sky
Knowledge connections
- Parent of51 Pegasi b
- In constellationPegasus
- Orbited by51 Pegasi b
Related stars in Pegasus
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.