Key parameters at a glance

A radius of 14.68 Earth radii
A mass of 778.65 Earth masses
Surface gravity around 3.61 g
An orbital period of 1.486 days
Semi-major axis 0.0259 AU
Equilibrium temperature 1,570 K (1297 °C)
Distance from Earth 2,350.78 light-years
Earth Similarity Index 0.088
Travel time at Voyager 1 speed 41,455,988 years

Kepler-17 b Planet Profile

Physical Specs

Radius

14.68 R⊕

Radius (Jupiter)

1.310 R♃

Mass

778.65 M⊕

Mass (Jupiter)

2.450 M♃

Density

1.35 g/cm³

Surface Gravity

3.61 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.088

HZ Position Inner

Controversial No

Discovery

Year 2011

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#263of 1771

top 14.8%

This planet

14.68R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

CoRoT-18 b 14.68 R⊕ BD+60 1417 b 14.68 R⊕ HAT-P-16 b 14.68 R⊕

Metric	Earth	Kepler-17 b	Jupiter
Radius (R⊕)	1.00	14.68	11.21
Mass (M⊕)	1.00	778.65	317.83
Density (g/cm³)	5.51	1.35	1.33
Surface Gravity (g)	1.00	3.61	2.53
Insolation (S⊕)	1.00	1,481.77	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	778.650 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 273874849

Gaia DR2

Gaia DR2 2086449761846310784

Gaia DR3

Gaia DR3 2086449761846310784

System

Kepler-17

Percentile among Gas Giant cohort

Radius 14.680 R⊕ · percentile 85 / cohort 1771

Mass 778.650 M⊕ · percentile 61 / cohort 1747

Orbital period 1.49 d · percentile 3 / cohort 1533

Distance 720.75 pc · percentile 81 / cohort 1759

ESI 0.088 · percentile 22 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

1.486 days

Semi-major axis

0.0259 AU

Eccentricity

0.011

Inclination

87.20 °

Year Length

A year here lasts approximately 1.49 Earth days (0.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0259 AU.

Transit Fingerprint

Depth

2.180 %

Duration

2.276 h

Impact parameter b

0.268

Rp / R★

0.130310

Transit midpoint (BJD)

2,455,185.6780

Photometric dip

Transit produces a flux drop of 21,802 ppm lasting ≈ 2.28 h.

Extended Orbital Architecture

Planet / star radius ratio

0.130310

Semi-major axis / stellar radius

5.480

Impact parameter (b)

0.268

RV semi-amplitude (K)

419.500 m/s

Occultation depth

0.006 ppm

Transit mid-time (BJD)

2,455,185.6780

Sky-projected obliquity (λ)

0.00°

True obliquity (ψ)

0.00°

Angular separation (arcsec)

0.03590

Eq. Temperature

1,570K

(1297 °C)

Insolation (S⊕)

1,481.77

Earth = 1.00

Earth Similarity (ESI)

0.088

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Orbital-brightness modulation

Host star brightness varies with the planet's orbit.

Discovery Paper

Primary reference

Desert et al. 2011

Instrument

Kepler CCD Array

Publication

2011-11

Observation locale

Space

Discovery cohort

Planets confirmed in 2011 at Kepler (12 shown).

Kepler-22 b · Sub-Neptune Kepler-20 d · Sub-Neptune Kepler-26 c · Sub-Neptune Kepler-19 c · Sub-Neptune Kepler-26 b · Sub-Neptune Kepler-28 c · Super-Earth Kepler-10 c · Sub-Neptune Kepler-20 f · Rocky Terrestrial Kepler-42 d · Rocky Terrestrial Kepler-16 b · Neptune-like Kepler-28 b · Super-Earth Kepler-34 b · Neptune-like

Host System: Kepler-17

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,781 K — hotter than the Sun (5,778 K)

Estimated Age

1.80 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.010 R☉

Stellar Mass

1.040 M☉

Metallicity [Fe/H]

0.26

Extended Stellar Properties

Surface gravity (log g)

4.446 dex

Stellar density

1.422 g/cm³

Systemic radial velocity

-24.81 km/s

Rotational v·sin i

6.00 km/s

Rotation period

12.01 days

Metallicity ratio

[M/H]

Distance

720.75 parsec

Light-years 2,350.78 ly

V-band magnitude

14.31 mag

Voyager-speed travel 41,455,988 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.359 mas

Total Proper Motion

7.402 mas/yr

PM Right Ascension

-3.78 mas/yr

PM Declination

-6.37 mas/yr

Galactic Cartesian (pc)

x = 0.319 · y = -0.591 · z = 0.741

Equatorial (J2000)

RA 298.39524° · Dec 47.81499°

Galactic ℓ, b

81.825° · 10.242°

Ecliptic λ, β

322.248° · 66.180°

HTM-20 index

1150800501