Kepler-17

Kepler-17
Observation data; Epoch J2000 Equinox ICRS
Constellation	Cygnus
Right ascension	19h 53m 34.8643s
Declination	+47° 48′ 54.050″
Apparent magnitude (V)	14.0
Characteristics
Evolutionary stage	main sequence
Spectral type	G2V
Astrometry
Radial velocity (Rv)	−25.82±4.64 km/s
Proper motion (μ)	RA: −3.811(17) mas/yr ; Dec.: −6.339(19) mas/yr
Parallax (π)	1.4115±0.0151 mas
Distance	2,310 ± 20 ly ; (708 ± 8 pc)
Details
Mass	1.16±0.06 M☉
Radius	1.05±0.03 R☉
Surface gravity (log g)	4.53±0.12 cgs
Temperature	5781±85 K
Metallicity [Fe/H]	0.26±0.10 dex
Rotation	12.159±0.029 days or 11.6±0.1 days
Rotational velocity (v sin i)	4.277±0.04 km/s
Age	3.0±1.6 Gyr
Other designations
	Kepler-17, KOI-203, KIC 10619192, TOI-5794, TIC 273874849, 2MASS J19533486+4748540
Database references
SIMBAD	data
Exoplanet Archive	data
KIC	data

Kepler-17 is a main-sequence yellow dwarf star about 2,310 light-years (710 parsecs) away in the constellation Cygnus. It is much more active than the Sun, with starspots covering roughly 6% of its surface. Starspots are long-lived, with at least one persisting for 1400 days.

Planetary system

Kepler-17 is known to host one hot Jupiter exoplanet, Kepler-17b, in orbit around it. It was discovered by the Kepler mission using the transit method in 2011. Its orbit is aligned with the host star's equator.

The Kepler-17 planetary system
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination (°)	Radius
b	2.47+0.12 −0.11 `M`_J	0.02680+0.00046 −0.00048	1.48571091(21)	<0.020	87.22±0.15	1.33±0.04 `R`_J

References

↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
1 2 3 4 5 6 7 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
↑ "Notes on Kepler-17 b". Extrasolar Planets Encyclopaedia. Retrieved 15 January 2017.
1 2 Bonomo, A. S.; Hébrard, G.; et al. (February 2012). "SOPHIE velocimetry of Kepler transit candidates: V. The three hot Jupiters KOI-135b, KOI-204b, and KOI-203b (alias Kepler-17b)". Astronomy & Astrophysics. 538: A96. arXiv:1110.5462. Bibcode:2012A&A...538A..96B. doi:10.1051/0004-6361/201118323. ISSN 0004-6361.
↑ McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv:1308.1845. Bibcode:2013ApJ...775L..11M. doi:10.1088/2041-8205/775/1/L11.
1 2 3 Sagynbayeva, Sabina; Farr, Will M. (February 2026). "Polka-dotted Stars. II. Starspots and Obliquities of Kepler-17 and Kepler-63". The Astrophysical Journal. 997 (2): 297. arXiv:2510.07130. Bibcode:2026ApJ...997..297S. doi:10.3847/1538-4357/ae2bdb. ISSN 0004-637X.
↑ Morris, Brett M.; Agol, Eric; Hebb, Leslie; Hawley, Suzanne L. (2018), "Robust Transiting Exoplanet Radii in the Presence of Starspots from Ingress and Egress Durations", The Astronomical Journal, 156 (3): 91, arXiv:1807.04886, Bibcode:2018AJ....156...91M, doi:10.3847/1538-3881/aad3b7, S2CID 119420137
↑ "Kepler-17". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 January 2017.
↑ Valio, Adriana; et al. (2017). "Activity and Rotation of Kepler-17". The Astrophysical Journal. 835 (2). 294. arXiv:1702.02213. Bibcode:2017ApJ...835..294V. doi:10.3847/1538-4357/835/2/294.
↑ Lanza, A. F.; Netto, Y.; Bonomo, A. S.; Parviainen, H.; Valio, A.; Aigrain, S. (2019), "Stellar activity and rotation of the planet host Kepler-17 from long-term space-borne photometry", Astronomy & Astrophysics, 626: A38, arXiv:1904.04489, Bibcode:2019A&A...626A..38L, doi:10.1051/0004-6361/201833894, S2CID 104292264
↑ Désert, Jean-Michel; et al. (2011). "The Hot-Jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization". The Astrophysical Journal Supplement Series. 197 (1). 14. arXiv:1107.5750. Bibcode:2011ApJS..197...14D. doi:10.1088/0067-0049/197/1/14.
↑ Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG: XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics. 602: A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882. ISSN 0004-6361.

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[constellation-1] Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.

[Gaia_DR3-2] 1 2 3 4 5 6 7 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[EU-3] "Notes on Kepler-17 b". Extrasolar Planets Encyclopaedia. Retrieved 15 January 2017.

[Bonomo2012-4] 1 2 Bonomo, A. S.; Hébrard, G.; et al. (February 2012). "SOPHIE velocimetry of Kepler transit candidates: V. The three hot Jupiters KOI-135b, KOI-204b, and KOI-203b (alias Kepler-17b)". Astronomy & Astrophysics. 538: A96. arXiv:1110.5462. Bibcode:2012A&A...538A..96B. doi:10.1051/0004-6361/201118323. ISSN 0004-6361.

[McQuillan2013-5] McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv:1308.1845. Bibcode:2013ApJ...775L..11M. doi:10.1088/2041-8205/775/1/L11.

[Sagynbayeva2026-6] 1 2 3 Sagynbayeva, Sabina; Farr, Will M. (February 2026). "Polka-dotted Stars. II. Starspots and Obliquities of Kepler-17 and Kepler-63". The Astrophysical Journal. 997 (2): 297. arXiv:2510.07130. Bibcode:2026ApJ...997..297S. doi:10.3847/1538-4357/ae2bdb. ISSN 0004-637X.

[Morris2018-7] Morris, Brett M.; Agol, Eric; Hebb, Leslie; Hawley, Suzanne L. (2018), "Robust Transiting Exoplanet Radii in the Presence of Starspots from Ingress and Egress Durations", The Astronomical Journal, 156 (3): 91, arXiv:1807.04886, Bibcode:2018AJ....156...91M, doi:10.3847/1538-3881/aad3b7, S2CID 119420137

[SIMBAD-8] "Kepler-17". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 January 2017.

[Valio2017-9] Valio, Adriana; et al. (2017). "Activity and Rotation of Kepler-17". The Astrophysical Journal. 835 (2). 294. arXiv:1702.02213. Bibcode:2017ApJ...835..294V. doi:10.3847/1538-4357/835/2/294.

[10] Lanza, A. F.; Netto, Y.; Bonomo, A. S.; Parviainen, H.; Valio, A.; Aigrain, S. (2019), "Stellar activity and rotation of the planet host Kepler-17 from long-term space-borne photometry", Astronomy & Astrophysics, 626: A38, arXiv:1904.04489, Bibcode:2019A&A...626A..38L, doi:10.1051/0004-6361/201833894, S2CID 104292264

[Désert2011-11] Désert, Jean-Michel; et al. (2011). "The Hot-Jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization". The Astrophysical Journal Supplement Series. 197 (1). 14. arXiv:1107.5750. Bibcode:2011ApJS..197...14D. doi:10.1088/0067-0049/197/1/14.

[Bonomo2017-12] Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG: XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics. 602: A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882. ISSN 0004-6361.