Key parameters at a glance
- A radius of 7.06 Earth radii
- A mass of 22.25 Earth masses
- Surface gravity around 0.45 g
- An orbital period of 4.235 days
- Semi-major axis 0.0475 AU
- Equilibrium temperature 1,080 K (807 °C)
- Distance from Earth 462.61 light-years
- Earth Similarity Index 0.122
- Travel time at Voyager 1 speed 8,158,125 years
- Almost certainly tidally locked to its host star given the close orbit
HAT-P-26 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#197of 574
top 34.1%
This planet
7.06R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | HAT-P-26 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 7.06 | 11.21 |
| Mass (M⊕) | 1.00 | 22.25 | 317.83 |
| Density (g/cm³) | 5.51 | 0.26 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.45 | 2.53 |
| Insolation (S⊕) | 1.00 | 185.07 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 22.248 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 420779000
Gaia DR2
Gaia DR2 3668036348641580288
Gaia DR3
Gaia DR3 3668036348641580288
System
HAT-P-26
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 4.23 Earth days (1.2% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0475 AU.
Transit Fingerprint
Depth
0.540 %
Duration
2.455 h
Impact parameter b
0.303
Rp / R★
0.073200
Transit midpoint (BJD)
2,456,901.0595
Photometric dip
Transit produces a flux drop of 5,400 ppm lasting ≈ 2.46 h.
Extended Orbital Architecture
Planet / star radius ratio
0.073200
Semi-major axis / stellar radius
13.090
Impact parameter (b)
0.303
RV semi-amplitude (K)
8.500 m/s
Transit mid-time (BJD)
2,456,901.0595
Long. of periastron (ω)
46.00°
Angular separation (arcsec)
0.33500
Eq. Temperature
1,080K
(807 °C)
Insolation (S⊕)
185.07
Earth = 1.00
Earth Similarity (ESI)
0.122
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
Hartman et al. 2011Instrument
2K CCD Sensor
Publication
2011-02
Observation locale
Ground
Discovery cohort
Planets confirmed in 2010 at HATNet (12 shown).
Host System: HAT-P-26
Spectral Class
K-type orange
Effective Temperature
5,079 K — cooler than the Sun (5,778 K)
Estimated Age
9.00 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.870 R☉
Stellar Mass
1.120 M☉
Metallicity [Fe/H]
-0.04
Extended Stellar Properties
Surface gravity (log g)
4.560 dex
Stellar density
2.370 g/cm³
Systemic radial velocity
14.72 km/s
Rotational v·sin i
1.90 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
7.022 mas
Total Proper Motion
147.816 mas/yr
PM Right Ascension
37.84 mas/yr
PM Declination
-142.89 mas/yr
Galactic Cartesian (pc)
x = -0.835 · y = -0.546 · z = 0.071
Equatorial (J2000)
RA 213.15655° · Dec 4.05942°
Galactic ℓ, b
346.513° · 59.873°
Ecliptic λ, β
209.492° · 16.377°
HTM-20 index
-440551644
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