Key parameters at a glance
- A radius of 2.34 Earth radii
- A mass of 14.80 Earth masses
- Surface gravity around 2.70 g
- An orbital period of 16.202 days
- Semi-major axis 0.1170 AU
- Equilibrium temperature 582 K (309 °C)
- Distance from Earth 92.28 light-years
- Earth Similarity Index 0.465
- Travel time at Voyager 1 speed 1,627,392 years
- Almost certainly tidally locked to its host star given the close orbit
HD 207897 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1428of 1978
top 72.1%
This planet
2.34R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 207897 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.34 | 11.21 |
| Mass (M⊕) | 1.00 | 14.80 | 317.83 |
| Density (g/cm³) | 5.51 | 6.29 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.70 | 2.53 |
| Insolation (S⊕) | 1.00 | 26.50 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 14.800 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 14.400 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 207897
HIP
HIP 107038
TIC
TIC 264678534
Gaia DR2
Gaia DR2 2300641567596591488
Gaia DR3
Gaia DR3 2300641567596591488
System
HD 207897
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 16.20 Earth days (4.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1170 AU.
Transit Fingerprint
Depth
0.089 %
Duration
2.905 h
Impact parameter b
0.424
Rp / R★
0.027444
Transit midpoint (BJD)
2,458,796.4956
Photometric dip
Transit produces a flux drop of 885 ppm lasting ≈ 2.90 h.
Extended Orbital Architecture
Planet / star radius ratio
0.027444
Semi-major axis / stellar radius
32.130
Impact parameter (b)
0.424
RV semi-amplitude (K)
4.260 m/s
Transit mid-time (BJD)
2,458,796.4956
Long. of periastron (ω)
90.00°
Angular separation (arcsec)
4.14000
Eq. Temperature
582K
(309 °C)
Insolation (S⊕)
26.50
Earth = 1.00
Earth Similarity (ESI)
0.465
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
Heidari et al. 2022Instrument
TESS CCD Array
Publication
2022-02
Observation locale
Space
Discovery cohort
Planets confirmed in 2021 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: HD 207897
Spectral Class
K-type orange
Effective Temperature
5,106 K — cooler than the Sun (5,778 K)
Estimated Age
4.70 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.783 R☉
Stellar Mass
0.821 M☉
Metallicity [Fe/H]
-0.03
Extended Stellar Properties
Surface gravity (log g)
4.562 dex
Stellar density
2.380 g/cm³
Rotational v·sin i
2.00 km/s
Rotation period
37.00 days
Activity index (log R'HK)
-4.830
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 7 bands
Astrometric Data
Parallax
35.315 mas
Total Proper Motion
350.888 mas/yr
PM Right Ascension
345.18 mas/yr
PM Declination
63.04 mas/yr
Galactic Cartesian (pc)
x = 0.081 · y = -0.056 · z = 0.995
Equatorial (J2000)
RA 325.20165° · Dec 84.33376°
Galactic ℓ, b
118.377° · 23.239°
Ecliptic λ, β
76.739° · 69.295°
HTM-20 index
-276861707
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