Key parameters at a glance
- A radius of 5.05 Earth radii
- A mass of 26.78 Earth masses
- Surface gravity around 1.05 g
- An orbital period of 3.492 days
- Semi-major axis 0.0391 AU
- Equilibrium temperature 767 K (494 °C)
- Distance from Earth 198.30 light-years
- Earth Similarity Index 0.253
- Travel time at Voyager 1 speed 3,496,955 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-1728 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#377of 574
top 65.5%
This planet
5.05R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | TOI-1728 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 5.05 | 11.21 |
| Mass (M⊕) | 1.00 | 26.78 | 317.83 |
| Density (g/cm³) | 5.51 | 1.14 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.05 | 2.53 |
| Insolation (S⊕) | 1.00 | 57.78 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 26.780 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 285048486
Gaia DR2
Gaia DR2 1094545653447816064
Gaia DR3
Gaia DR3 1094545653447816064
System
TOI-1728
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.49 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0391 AU.
Transit Fingerprint
Depth
0.540 %
Duration
1.960 h
Impact parameter b
0.390
Rp / R★
0.074000
Transit midpoint (BJD)
2,458,843.2743
Photometric dip
Transit produces a flux drop of 5,400 ppm lasting ≈ 1.96 h.
Extended Orbital Architecture
Planet / star radius ratio
0.074000
Semi-major axis / stellar radius
13.480
Impact parameter (b)
0.390
RV semi-amplitude (K)
15.120 m/s
Transit mid-time (BJD)
2,458,843.2743
Long. of periastron (ω)
45.00°
Angular separation (arcsec)
0.64300
Eq. Temperature
767K
(494 °C)
Insolation (S⊕)
57.78
Earth = 1.00
Earth Similarity (ESI)
0.253
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. 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
Kanodia et al. 2020Instrument
TESS CCD Array
Publication
2020-08
Observation locale
Space
Discovery cohort
Planets confirmed in 2020 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-1728
Spectral Class
M-type red dwarf
Effective Temperature
3,980 K — cooler than the Sun (5,778 K)
Estimated Age
7.10 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.624 R☉
Stellar Mass
0.646 M☉
Metallicity [Fe/H]
0.25
Extended Stellar Properties
Surface gravity (log g)
4.657 dex
Stellar density
3.780 g/cm³
Systemic radial velocity
-43.22 km/s
Rotational v·sin i
2.00 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 14 bands
Astrometric Data
Parallax
16.419 mas
Total Proper Motion
116.759 mas/yr
PM Right Ascension
104.08 mas/yr
PM Declination
52.92 mas/yr
Galactic Cartesian (pc)
x = -0.217 · y = 0.366 · z = 0.905
Equatorial (J2000)
RA 120.61168° · Dec 64.79715°
Galactic ℓ, b
151.460° · 31.879°
Ecliptic λ, β
107.297° · 43.186°
HTM-20 index
749855889
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