Confirmed Exoplanet Discovered 2018

HATS-44 b

A gas giant orbiting the k-type orange HATS-44, located approximately 1,454.8 light-years from Earth.

Key parameters at a glance

  • A radius of 11.96 Earth radii
  • A mass of 177.98 Earth masses
  • Surface gravity around 1.24 g
  • An orbital period of 2.744 days
  • Semi-major axis 0.0365 AU
  • Equilibrium temperature 1,161 K (888 °C)
  • Distance from Earth 1,454.77 light-years
  • Earth Similarity Index 0.115
  • Travel time at Voyager 1 speed 25,654,866 years
  • Almost certainly tidally locked to its host star given the close orbit

HATS-44 b Planet Profile

Physical Specs

Radius
11.96 R⊕
Radius (Jupiter)
1.067 R♃
Mass
177.98 M⊕
Mass (Jupiter)
0.560 M♃
Density
0.56 g/cm³
Surface Gravity
1.24 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.115
HZ Position Inner
Controversial No

Discovery

Year 2018
Method Transit
Facility HATSouth
Telescope 0.18 m Takahashi Epsilon Astrograph

Size rank in cohort

Rank by radius

#1520of 1771

top 85.8%

This planet

11.96R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth HATS-44 b Jupiter
Radius (R⊕)1.0011.9611.21
Mass (M⊕)1.00177.98317.83
Density (g/cm³)5.510.561.33
Surface Gravity (g)1.001.242.53
Insolation (S⊕)1.00306.420.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 177.985 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 32499655

Gaia DR2

Gaia DR2 2907577758566408960

Gaia DR3

Gaia DR3 2907577758566408960

System

HATS-44

Percentile among Gas Giant cohort

Radius 11.960 R⊕ · percentile 14 / cohort 1771
Mass 177.985 M⊕ · percentile 16 / cohort 1747
Orbital period 2.74 d · percentile 13 / cohort 1533
Distance 446.04 pc · percentile 73 / cohort 1759
ESI 0.115 · percentile 30 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
2.744 days
Semi-major axis
0.0365 AU
Eccentricity
0.279
Inclination
84.65 °

Year Length

A year here lasts approximately 2.74 Earth days (0.8% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0365 AU.

Transit Fingerprint

Depth

1.385 %

Duration

1.651 h

Impact parameter b

0.862

Rp / R★

0.129000

Transit midpoint (BJD)

2,456,931.1138

Photometric dip

Transit produces a flux drop of 13,852 ppm lasting ≈ 1.65 h.

Extended Orbital Architecture

Planet / star radius ratio

0.129000

Semi-major axis / stellar radius

9.240

Impact parameter (b)

0.862

RV semi-amplitude (K)

90.000 m/s

Transit mid-time (BJD)

2,456,931.1138

Angular separation (arcsec)

0.08180

Eq. Temperature

1,161K

(888 °C)

Insolation (S⊕)

306.42

Earth = 1.00

Earth Similarity (ESI)

0.115

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. Close-orbiting tidally-locked around a cool host.

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

Brahm et al. 2018

Instrument

Apogee 4K CCD Sensor

Publication

2018-03

Observation locale

Ground

Host System: HATS-44

Spectral Class

K-type orange

Effective Temperature

5,080 K — cooler than the Sun (5,778 K)

Estimated Age

9.70 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.847 R☉

Stellar Mass

0.860 M☉

Metallicity [Fe/H]

0.32

Extended Stellar Properties

Surface gravity (log g)

4.514 dex

Stellar density

1.980 g/cm³

Systemic radial velocity

44.08 km/s

Rotational v·sin i

0.50 km/s

Metallicity ratio

[Fe/H]

Distance
446.04 parsec
Light-years 1,454.77 ly
V-band magnitude
14.40 mag
Voyager-speed travel 25,654,866 yr

Multi-band Host Photometry — 14 bands

8.915.515.48B14.40V14.16Gaia13.55TESS14.93Sloan g14.09Sloan r13.79Sloan i12.70J12.23H12.19K12.07W112.14W211.68W38.95W4

Astrometric Data

Parallax

2.213 mas

Total Proper Motion

2.175 mas/yr

PM Right Ascension

-2.16 mas/yr

PM Declination

0.26 mas/yr

Galactic Cartesian (pc)

x = 0.087 · y = 0.879 · z = -0.469

Equatorial (J2000)

RA 84.32676° · Dec -27.97258°

Galactic ℓ, b

232.000° · -27.627°

Ecliptic λ, β

81.977° · -51.254°

HTM-20 index

1067984023

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