{ "id": "epbcsae98t", "slug": "kepler-553", "title": "Kepler-553", "updated": "2026-10-21", "topic_path": [ { "id": "places", "label": "Places and geography", "api_url": "https://www.edgepedia.org/api/v1/topics/places" }, { "id": "places.extraterrestrial", "label": "Extraterrestrial places", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial" }, { "id": "places.extraterrestrial.star-systems", "label": "Exoplanets and nearby star systems", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.star-systems" }, { "id": "places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler", "label": "Planets and host stars observed by Kepler", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler" }, { "id": "places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler.kepler-systems-400-499", "label": "Kepler systems 400–499", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler.kepler-systems-400-499" } ], "geo": [ { "id": "geo.nongeo.nodate.places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler", "label": "Non-geographic · Not dated: Planets and host stars observed by Kepler", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.nodate", "label": "Non-geographic · Not dated", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate" }, { "id": "geo.nongeo.nodate.places", "label": "Places and geography", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places" }, { "id": "geo.nongeo.nodate.places.extraterrestrial", "label": "Extraterrestrial places", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial" }, { "id": "geo.nongeo.nodate.places.extraterrestrial.star-systems", "label": "Exoplanets and nearby star systems", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.star-systems" }, { "id": "geo.nongeo.nodate.places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler", "label": "Planets and host stars observed by Kepler", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler" } ] } ], "excerpt": "Kepler-553 (KOI-433, KIC 10937029) is a K-type star 728.5 parsecs away in Cygnus with two confirmed transiting planets: close-in Neptune-like Kepler-553 b (4.03 d) and eccentric 6.7-Jupiter-mass habitable-zone giant Kepler-553 c (328.2 d).", "snippet": "Kepler-553 (KOI-433, KIC 10937029) is a K-type star 728.5 parsecs away in Cygnus with two confirmed transiting planets: close-in Neptune-like Kepler-553 b (4.03 d) and eccentric 6.7-Jupiter-mass habitable-zone giant Kepler-553 c (328.2 d).", "node": "places.extraterrestrial.star-systems.planets-and-host-stars-observed-by-kepler.kepler-systems-400-499", "markdown": "# Kepler-553\n\n**Kepler-553** (KOI-433, KIC 10937029) is a K-type star about 728.5 parsecs (roughly 2,376 light-years) away in the constellation Cygnus that hosts two confirmed transiting exoplanets: a close-in Neptune-sized planet, Kepler-553 b, and a long-period, eccentric giant planet, Kepler-553 c.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [2](https://science.nasa.gov/exoplanet-catalog/kepler-553-c/) Both planets were validated in 2016 in the statistical catalog of Timothy D. Morton and colleagues, which assigned false-positive probabilities to all Kepler Objects of Interest.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553)\n\n| Key fact | Detail |\n|---|---|\n| Host star | K-type star, radius 0.90 solar radii, effective temperature 5191 K, distance 728.525±12.571 pc[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) |\n| Metallicity | [Fe/H] = 0.10±0.04 dex, slightly iron-rich relative to the Sun (Hypatia Catalog)[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) |\n| Kepler-553 b | Period 4.03 days, radius 0.423 Jupiter radii (4.74 Earth radii), Neptune-like, orbit at 0.04766 AU[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [3](https://science.nasa.gov/exoplanet-catalog/kepler-553-b/) |\n| Kepler-553 c | Period 328.24 days, radius 1.033 Jupiter radii (11.58 Earth radii), mass 6.7 Jupiter masses, eccentricity 0.35, orbit at 0.898 AU[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [2](https://science.nasa.gov/exoplanet-catalog/kepler-553-c/) |\n| Validation | Both planets confirmed in 2016 by Morton et al. from Kepler transit data[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) |\n| Mass measurement | Kepler-553 c's mass comes from long-term radial velocities in the GOT 'EM survey (Dalba et al. 2024); Kepler-553 b's weak signal yielded only an upper limit[4](https://arxiv.org/abs/2401.03021) |\n\n## Host star\n\nKepler-553 is a cool K-type star with a radius of 0.90 solar radii and an effective temperature of 5191 K.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) Gaia astrometry places it at 728.525±12.571 parsecs, with a parallax of 1.3442300±0.0234986 mas, and it is faint in visual light at magnitude 15.034.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) Its measured abundances are mildly enhanced: [Fe/H] = 0.10±0.04 dex, [C/H] = 0.20±0.09 dex, and [O/H] = 0.27±0.09 dex.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553)\n\n## Discovery and validation\n\nBoth planets appeared in the Kepler pipeline as Objects of Interest K00433.01 and K00433.02 around KepID 10937029, and passed every standard false-positive test for transit-like shape, stellar eclipse, centroid offset, and ephemeris contamination.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) They were confirmed in 2016 through the Morton et al. false-positive-probability analysis, which validated 1,284 Kepler objects as planets in a single catalog; the archive notes that the orbital periods, transit epochs, durations, and radius ratios adopted as default parameters come from the Q1-Q17 DR24 KOI table.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553)\n\n## The two planets\n\n**Kepler-553 b** is a Neptune-like planet on a 4.03-day orbit at 0.04766 AU, with a radius of 0.423 Jupiter radii, or 4.74 Earth radii.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [3](https://science.nasa.gov/exoplanet-catalog/kepler-553-b/) The NASA catalog lists a mass of 19.4 Earth masses, and although it cites 0.365 Jupiter masses, that conversion is inaccurate (19.4 Earth masses is about 0.061 Jupiter masses), yet this value is an upper limit rather than a detection: the photodynamical characterization by Paul A. Dalba, an exoplanet astronomer then at the [University of California, Santa Cruz](https://www.edgepedia.org/university-of-california-santa-cruz), and collaborators found that the radial-velocity data could not constrain the planet's mass, and the transit parameters converged while the velocity semiamplitude did not.[3](https://science.nasa.gov/exoplanet-catalog/kepler-553-b/) • [4](https://arxiv.org/abs/2401.03021)\n\n**Kepler-553 c** is a massive gas giant on a 328.24-day orbit at 0.898 AU with an eccentricity of about 0.35.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [2](https://science.nasa.gov/exoplanet-catalog/kepler-553-c/) The Kepler spacecraft recorded five of its transits, and long-term [Doppler spectroscopy](https://www.edgepedia.org/doppler-spectroscopy) measured a mass of 6.70+0.44/−0.43 Jupiter masses and a radius of 1.033+0.032/−0.025 Jupiter radii, with a moderate eccentricity of 0.346+0.020/−0.024.[4](https://arxiv.org/abs/2401.03021) Its equilibrium temperature is approximately 251 K, and it orbits within the system's habitable zone, where liquid water could exist on a suitably sized rocky body, although a 6.7-Jupiter-mass gas giant is not itself habitable.[2](https://science.nasa.gov/exoplanet-catalog/kepler-553-c/) • [5](https://www.exoplanetatlas.com/exoplanets/kepler-553-c) The planet's bulk composition is estimated at about 8 percent heavy elements by mass, consistent with expectations for a gas giant of this mass.[5](https://www.exoplanetatlas.com/exoplanets/kepler-553-c)\n\n## Characterization and context\n\nKepler-553 c was characterized as part of the Giant Outer Transiting Exoplanet Mass (GOT 'EM) survey, a program of long-term radial-velocity follow-up for stars thought to host cool giant transiting exoplanets.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553) • [4](https://arxiv.org/abs/2401.03021) With a period of 328.2 days, a semimajor axis of 0.898 AU, an eccentricity of 0.346, a radius of 1.03 Jupiter radii, and a mass of 6.70 Jupiter masses, it appears in comparative tables of confirmed transiting planets between 6 and 20 Earth radii with periods longer than 100 days and 3-sigma mass measurements, as one of the more massive and eccentric members of that sample.[6](https://doi.org/10.3847%2F1538-3881%2Fae3d9f) The pair also illustrates a common Kepler architecture in which a small inner planet and a distant giant transit the same star, a configuration useful for studying how giant companions relate to compact inner systems.[1](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553)\n\n## References\n\n1. [Kepler-553 Overview, NASA Exoplanet Archive](https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-553)\n2. [Kepler-553 c, NASA Science Exoplanet Catalog](https://science.nasa.gov/exoplanet-catalog/kepler-553-c/)\n3. [Kepler-553 b, NASA Science Exoplanet Catalog](https://science.nasa.gov/exoplanet-catalog/kepler-553-b/)\n4. [Dalba et al. 2024, Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. IV, arXiv](https://arxiv.org/abs/2401.03021)\n5. [Kepler-553 c, Exoplanet Atlas](https://www.exoplanetatlas.com/exoplanets/kepler-553-c)\n6. [TOI-6692 b: An Eccentric 130 Day Period Giant Planet with a Single Transit from TESS, IOPscience](https://doi.org/10.3847%2F1538-3881%2Fae3d9f)\n\n---\n*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Exoplanets and nearby star systems › Planets and host stars observed by Kepler › Kepler systems 400–499*\n\n*Initially written Oct 21, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/kepler-553", "markdown_url": "https://www.edgepedia.org/kepler-553.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Kepler-553\", Edgepedia (EdgeChat), https://www.edgepedia.org/kepler-553. Edgepedia Community License 1.0.", "credit_md": "\"[Kepler-553](https://www.edgepedia.org/kepler-553)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/kepler-553](https://www.edgepedia.org/kepler-553). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Kepler-553\", Edgepedia (EdgeChat), https://www.edgepedia.org/kepler-553. Edgepedia Community License 1.0.", "speakable": "Kepler-553 is a K-type star 728.5 parsecs away in Cygnus with two confirmed transiting planets: close-in Neptune-like Kepler-553 b and eccentric 6.7-Jupiter-mass habitable-zone giant Kepler-553 c." }