---
title: "The KOI-3503 system"
url: "https://spacecatalog.org/system/koi-3503"
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 KOI-3503 system

KOI-3503 is a star in Cygnus, 2893 ly away, with 2 known planets. Their orbits run from 0.142 to 0.187 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/koi-3503-b) | 0.142 | 21.18 d | 1.19 R⊕ | 9.2 M⊕ | 785 K |
| [c](https://spacecatalog.org/object/koi-3503-c) | 0.187 | 31.83 d | 1.21 R⊕ | 10.4 M⊕ | 686 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 | 0.858 M☉ |
| RADIUS | 1.255 R☉ |
| SURFACE TEMPERATURE | 6001 K |
| LUMINOSITY | 1.84 L☉ |
| DISTANCE FROM EARTH | 2893 ly |
| APPARENT MAGNITUDE | 13.83 |
| CONSTELLATION | Cygnus |
| STARS IN SYSTEM | 1 |

The star itself: https://spacecatalog.org/object/koi-3503

The page itself, with the orbits drawn: https://spacecatalog.org/system/koi-3503