---
title: "The Kepler-123 system"
url: "https://spacecatalog.org/system/kepler-123"
release: "DR1"
licence: "No licence stated; acknowledgement requested"
citation: "This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Cite Christiansen et al. (2025), Planetary Science Journal (doi:10.3847/PSJ/ade3c2), and the literature reference given with each value."
---

# The Kepler-123 system

Kepler-123 is a star in Cygnus, 3332 ly away, with 2 known planets. Their orbits run from 0.135 to 0.181 AU. All of them were detected by transit.

## The planets, innermost first

| Planet | Orbit (AU) | Period | Radius | Mass | Equilibrium T |
| --- | --- | --- | --- | --- | --- |
| [b](https://spacecatalog.org/object/kepler-123-b) | 0.135 | 17.23 d | 2.94 R⊕ | 55.3 M⊕ | 817 K |
| [c](https://spacecatalog.org/object/kepler-123-c) | 0.181 | 26.7 d | 1.48 R⊕ | 2.79 M⊕ | 706 K |

Every figure is the planet's composite parameter from the [NASA Exoplanet Archive (Planetary Systems Composite Parameters)](https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=PSCompPars), one consistent set per world. Semi-major axes are orbits about the star, not distances from Earth.

This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Cite Christiansen et al. (2025), Planetary Science Journal (doi:10.3847/PSJ/ade3c2), and the literature reference given with each value.

## The host star

| Quantity | Value |
| --- | --- |
| MASS | 1.079 M☉ |
| RADIUS | 1.264 R☉ |
| SURFACE TEMPERATURE | 6089 K |
| LUMINOSITY | 1.98 L☉ |
| DISTANCE FROM EARTH | 3332 ly |
| APPARENT MAGNITUDE | 14.13 |
| CONSTELLATION | Cygnus |
| STARS IN SYSTEM | 1 |

The star itself: https://spacecatalog.org/object/kepler-123

The page itself, with the orbits drawn: https://spacecatalog.org/system/kepler-123