Key parameters at a glance
- A mass of 1,775.39 Earth masses
- An orbital period of 20.432 days
- Semi-major axis 0.1321 AU
- Equilibrium temperature 541 K (268 °C)
- Distance from Earth 42.19 light-years
- Travel time at Voyager 1 speed 744,065 years
- Almost certainly tidally locked to its host star given the close orbit
3 siblings around HD 40307
HD 40307 d shares its host star with 3 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| HD 40307 b | Unclassified | — | 1,189.00 | 4.312 | 910 | 2009 |
| HD 40307 c | Unclassified | — | 1,868.51 | 9.618 | 696 | 2009 |
| HD 40307 d this | Unclassified | — | 1,775.39 | 20.432 | 541 | 2009 |
| HD 40307 f | Sub-Neptune | 2.13 | 5.20 | 51.760 | 398 | 2013 |
HD 40307 d Planet Profile
Physical Specs
Classification
Planet Type
Unclassified
Discovery
| Metric | Earth | HD 40307 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | — | 11.21 |
| Mass (M⊕) | 1.00 | 1,775.39 | 317.83 |
| Density (g/cm³) | 5.51 | — | 1.33 |
| Surface Gravity (g) | 1.00 | — | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 1,775.389 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 9.500 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 40307
HIP
HIP 27887
TIC
TIC 374859347
Gaia DR2
Gaia DR2 4758877919212831104
Gaia DR3
Gaia DR3 4758877919212831104
System
HD 40307
Percentile among Unclassified cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 20.43 Earth days (5.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1321 AU.
Eq. Temperature
541K
(268 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
—
0 = alien, 1 = Earth-identical
Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Mayor et al. 2009Instrument
HARPS Spectrograph
Publication
2009-01
Observation locale
Ground
Discovery cohort
Planets confirmed in 2009 at La Silla Observatory (12 shown).
Host System: HD 40307
Spectral Class
K-type orange
Effective Temperature
4,956 K — cooler than the Sun (5,778 K)
Estimated Age
4.50 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.717 R☉
Stellar Mass
0.770 M☉
Metallicity [Fe/H]
-0.31
Extended Stellar Properties
Surface gravity (log g)
4.470 dex
Stellar density
3.026 g/cm³
Systemic radial velocity
31.33 km/s
Rotational v·sin i
1.00 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
77.273 mas
Total Proper Motion
79.790 mas/yr
PM Right Ascension
-52.42 mas/yr
PM Declination
-60.15 mas/yr
Galactic Cartesian (pc)
x = 0.013 · y = 0.499 · z = -0.866
Equatorial (J2000)
RA 88.51722° · Dec -60.02373°
Galactic ℓ, b
268.815° · -30.341°
Ecliptic λ, β
83.508° · -83.430°
HTM-20 index
-1668356410
Observation Record
Photometric series
1
RV measurements
1
Stellar spectra
1
Archive notes
1
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HD 40307 c
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