Confirmed Exoplanet Discovered 2016

HATS-18 b

A gas giant orbiting the g-type yellow (sun-like) HATS-18, located approximately 2,036.4 light-years from Earth.

Key parameters at a glance

  • A radius of 14.90 Earth radii
  • A mass of 629.14 Earth masses
  • Surface gravity around 2.84 g
  • An orbital period of 0.838 days
  • Semi-major axis 0.0174 AU
  • Equilibrium temperature 2,069 K (1796 °C)
  • Distance from Earth 2,036.41 light-years
  • Earth Similarity Index 0.062
  • Travel time at Voyager 1 speed 35,912,153 years

HATS-18 b Planet Profile

Physical Specs

Radius
14.90 R⊕
Radius (Jupiter)
1.329 R♃
Mass
629.14 M⊕
Mass (Jupiter)
1.980 M♃
Density
1.12 g/cm³
Surface Gravity
2.84 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.062
HZ Position Inner
Controversial No

Discovery

Year 2016
Method Transit
Facility Multiple Observatories
Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#244of 1771

top 13.7%

This planet

14.90R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth HATS-18 b Jupiter
Radius (R⊕)1.0014.9011.21
Mass (M⊕)1.00629.14317.83
Density (g/cm³)5.511.121.33
Surface Gravity (g)1.002.842.53
Insolation (S⊕)1.002,990.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 629.144 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 14614418

Gaia DR2

Gaia DR2 3483636295772522880

Gaia DR3

Gaia DR3 3483636295773117440

System

HATS-18

Percentile among Gas Giant cohort

Radius 14.897 R⊕ · percentile 86 / cohort 1771
Mass 629.144 M⊕ · percentile 55 / cohort 1747
Orbital period 0.84 d · percentile 0 / cohort 1533
Distance 624.37 pc · percentile 79 / cohort 1759
ESI 0.062 · percentile 10 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
0.838 days
Semi-major axis
0.0174 AU
Eccentricity
0.166
Inclination
85.29 °

Year Length

A year here lasts roughly 20.1 hours long on a mildly elliptical path at a mean orbital distance of 0.0174 AU.

Transit Fingerprint

Depth

2.136 %

Duration

1.944 h

Impact parameter b

0.300

Rp / R★

0.132000

Transit midpoint (BJD)

2,458,217.6437

Photometric dip

Transit produces a flux drop of 21,356 ppm lasting ≈ 1.94 h.

Extended Orbital Architecture

Planet / star radius ratio

0.132000

Semi-major axis / stellar radius

3.658

Impact parameter (b)

0.300

RV semi-amplitude (K)

415.200 m/s

Transit mid-time (BJD)

2,458,217.6437

Angular separation (arcsec)

0.02790

Eq. Temperature

2,069K

(1796 °C)

Insolation (S⊕)

2,990.00

Earth = 1.00

Earth Similarity (ESI)

0.062

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.

Discovery Paper

Primary reference

Penev et al. 2016

Instrument

Multiple Instruments

Publication

2016-11

Observation locale

Ground

Host System: HATS-18

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,600 K — cooler than the Sun (5,778 K)

Estimated Age

4.20 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.020 R☉

Stellar Mass

1.037 M☉

Metallicity [Fe/H]

0.28

Extended Stellar Properties

Surface gravity (log g)

4.436 dex

Stellar density

1.370 g/cm³

Systemic radial velocity

7.66 km/s

Rotational v·sin i

6.23 km/s

Rotation period

9.80 days

Metallicity ratio

[Fe/H]

Distance
624.37 parsec
Light-years 2,036.41 ly
V-band magnitude
14.19 mag
Voyager-speed travel 35,912,153 yr

Multi-band Host Photometry — 14 bands

8.914.814.83B14.19V13.88Gaia13.39TESS14.41Sloan g13.85Sloan r13.77Sloan i12.74J12.38H12.29K12.29W112.33W212.19W38.86W4

Astrometric Data

Parallax

1.574 mas

Total Proper Motion

5.844 mas/yr

PM Right Ascension

3.18 mas/yr

PM Declination

-4.90 mas/yr

Galactic Cartesian (pc)

x = -0.868 · y = 0.092 · z = -0.487

Equatorial (J2000)

RA 173.95742° · Dec -29.15606°

Galactic ℓ, b

283.687° · 30.875°

Ecliptic λ, β

187.179° · -28.918°

HTM-20 index

-1921751017

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