List of terrestrial exoplanet candidates for atmosphere detection
From Wikipedia, the free encyclopedia
Rocky exoplanets are thought to be abundant in the Milky Way, however the existence and composition of their atmospheres are generally unknown.[1] The existence of a stable atmosphere depends on several factors, including the total amount of radiation received (which is related to the spectral type of the host star), the surface gravity (related to mass and radius), and the orbital period.[2]
In 2024, 55 Cancri Ae became the first terrestrial exoplanet to have its atmosphere detected. Its atmosphere might have been re-generated by a magma ocean, and is composed of either carbon monoxide (CO) or carbon dioxide (CO2).[3][a] Later studies found evidences of atmosphere for the sub-Earth planet L 98-59 b, the evaporating planet K2-22b, and the super-Earth planets TOI-561 b and HD 3167 b.[5][6][7][8]
Table
To be included in the following list, an exoplanet must:
- Be terrestrial or nearly terrestrial (density > 3.0 g/cm3 and radius < 2.0R⊕)
- Transit its host star from view of Earth
- Have been studied with transmission spectroscopy or secondary eclipse and have a published claim or inference of atmospheric detection, whether confirmed or not
Note that mass values prefixed with "~" have not been measured, but are estimated from the mass-radius relationship.
| Solar system planet for reference |
| Solar system moon for reference |
| Rocky exoplanet with confirmed atmosphere detection |
| Rocky exoplanet with unconfirmed atmosphere detection |
| Mini-Neptune planet for reference |
| Planet/Moon | Host | Spectral type | Mass (M⊕) | Radius (R⊕) | Existence of atmosphere | Composition of atmosphere (by volume) | Atmospheric pressure at surface (atm) | Period (days) | Distance (ly) | Refs/notes |
|---|---|---|---|---|---|---|---|---|---|---|
| Earth (reported for reference) | Sun | G2V | 1.00 | 1.00 | Confirmed | 78.08% nitrogen, 20.95% oxygen, 0.93% argon, water vapour and other trace gases | 1.0 | 365.25 | 0 | Only planet known to harbour life[9] |
| Venus (reported for reference) | Sun | G2V | 0.815 | 0.950 | Confirmed | 96.5% carbon dioxide, 3.5% nitrogen, sulfur dioxide and other trace gases | 92 | 244.26 | ~0 | [10] |
| Mars (reported for reference) | Sun | G2V | 0.107 | 0.533 | Confirmed | 95.97% carbon dioxide, 1.93% argon, 1.89% nitrogen, oxygen and other trace gases | 0.0063 | 686.98 | ~0 | [11] |
| Titan (reported for reference) | Saturn | – | 0.0225 | 0.404 | Confirmed | (for the troposphere) 97% nitrogen, 2.7±0.1% methane, 0.1–0.2% hydrogen, organonitrogen haze | 1.45 | 15.945 (sidereal) | ~0 | [12] |
| Triton (reported for reference) | Neptune | – | 0.0036 | 0.212 | Confirmed | nitrogen, methane and carbon monoxide traces | 0.000014 | 5.877 (sidereal, retrograde) | ~0 | [13] |
| LTT 1445 Ab | LTT 1445 A | M2.5V | 2.73 | 1.34 | Unconfirmed | Likely hydrogen cyanide | 5.36 | 22.4 | [14] | |
| Gliese 486 b (Su) | Gliese 486 (Gar) | M3.5V | 2.77 | 1.29 | Unconfirmed | Probably water vapour | 1.47 | 26.3 | Unclear if the water vapour signal came from planet or host star[15] | |
| Gliese 357 b | Gliese 357 | M2.5V | 1.84 | 1.22 | Unconfirmed | Likely carbon dioxide or abiotic oxygen | 3.93 | 30.8 | [16] | |
| Gliese 341 b | Gliese 341 | M1V | ~0.72 | 0.89 | Unconfirmed | Likely water vapour or other small molecules | 7.58 | 34.1 | [17] | |
| L 98-59 b | L 98-59 | M3V | 0.47 | 0.85 | Confirmed | Mostly sulfur dioxide | 2.25 | 34.6 | [6] | |
| L 98-59 c | L 98-59 | M3V | 2.22 | 1.38 | Unconfirmed | Likely hydrogen with traces of carbon dioxide and water vapour | 3.69 | 34.6 | [18] | |
| TRAPPIST-1b | TRAPPIST-1 | M8V | 1.37 | 1.12 | Unconfirmed | Likely carbon dioxide | 1.51 | 40.6 | [19] | |
| TRAPPIST-1c | TRAPPIST-1 | M8V | 1.31 | 1.10 | Unconfirmed | Likely mostly oxygen and carbon dioxide traces | 0.1–10 (if an atmosphere exists)[20] | 2.42 | 40.6 | [21] |
| TRAPPIST-1d | TRAPPIST-1 | M8V | 0.39 | 0.79 | Unconfirmed | Probably carbon dioxide or clouds from water vapour | 0.01 (approximate, if an atmosphere exists and is Mars-like) | 4.05 | 40.6 | Located in the habitable zone[22] |
| TRAPPIST-1e | TRAPPIST-1 | M8V | 0.69 | 0.92 | Unconfirmed | Likely nitrogen with methane traces | 6.10 | 40.6 | Located in the habitable zone[23] | |
| LHS 475 b | LHS 475 | M3.5V | ~0.91 | 0.99 | Unconfirmed | Probably carbon dioxide | 0.01 (approximate, if an atmosphere exists and is Mars-like without haze) | 2.03 | 40.7 | [24] |
| 55 Cancri Ae (Janssen) | 55 Cancri A (Copernicus) | K0IV-V | 7.99 | 1.87 | Confirmed | Phosphorus monoxide, nitrogen and carbon dioxide or water vapour or phosphine, possibly with sodium and calcium | 10 or higher | 0.736 | 41.0 | [3][4][25] |
| GJ 1132 b | GJ 1132 | M4V | 1.66 | 1.13 | Unconfirmed | Likely oxygen or carbon dioxide or clouds from potassium chloride/ zinc sulfide | 1.63 | 41.1 | [26] | |
| GJ 1214 b (Enaiposha) | GJ 1214 (Orkaria) | M4.5V | 8.41 | 2.73 | Confirmed | Haze and carbon dioxide, possibly with helium | Very high | 1.58 | 47.8 | [27][28] |
| LHS 1140 b | LHS 1140 | M4.5V | 5.60 | 1.73 | Unconfirmed | Likely nitrogen and water vapour | 24.74 | 48.8 | Located in the habitable zone[29][30] | |
| LHS 1478 b | LHS 1478 | M3.5V | 2.33 | 1.20 | Unconfirmed | Likely pure carbon dioxide, carbon dioxide and water vapour or nitrogen and carbon dioxide | 1–10 (if an atmosphere exists) | 1.95 | 59.4 | The dark bare-rock scenario was considered unlikely[31][21] |
| TOI-260 b | TOI-260 | K8V | 4.23 | 1.76 | Unconfirmed | Probably ethylene, acetylene, gaseous carbon or ammonia | 13.47 | 65.9 | The absorption features of these gases best match the 3.17 μm feature in the obtained spectra[32] | |
| GJ 1252 b | GJ 1252 | M2.5V | 1.32 | 1.18 | Unconfirmed | Probably sodium, atomic oxygen and potassium | 0.000001 or lower | 0.518 | 66.5 | [33] |
| HD 97658 b | HD 97658 | K1V | 7.81 | 2.25 | Confirmed | Clouds and likely hydrogen, carbon monoxide and methane | Very high | 9.49 | 70.3 | [34] |
| TOI-732 c | TOI-732 | M3.5V | 8.04 | 2.39 | Confirmed | Methane, 1-pentene and other alkenes or diethyl sulfide | Very high | 12.25 | 71.8 | [35] |
| TOI-270 b | TOI-270 | M3V | 1.48 | 1.30 | Unconfirmed | Likely water vapour | 3.36 | 73.3 | [36] | |
| TOI-270 d | TOI-270 | M3V | 4.20 | 2.13 | Confirmed | Methane, carbon dioxide, water vapour, carbon disulfide, thioformaldehyde, possibly with sulfur dioxide and chloromethane or fluoromethane | Very high | 11.38 | 73.3 | [37][38] |
| L 168-9 b (Qingluan) | L 168-9 (Danfeng) | M1V | 4.07 | 1.63 | Unconfirmed | Likely carbon dioxide | 1.40 | 82.1 | [39] | |
| GJ 3473 b | GJ 3473 | M4V | 1.86 | 1.24 | Unconfirmed | Likely carbon dioxide or water vapour | 1.2–6.5 or lower | 1.20 | 89.3 | [40] |
| TOI-431 b | TOI-431 | K2V | 3.07 | 1.24 | Unconfirmed | - | 0.490 | 106 | The dark bare-rock scenario was considered unlikely[41] | |
| TOI-1685 b | TOI-1685 | M3V | 3.07 | 1.42 | Unconfirmed | Probably carbon dioxide or water vapour or sulfur dioxide | 0.668 | 123 | [42] | |
| K2-141b | K2-141 | K5V | 5.08 | 1.51 | Unconfirmed | Likely vapourized silicate-rock | 0.280 | 202 | [43] | |
| TOI-561 b | TOI-561 | G9V | 2.02 | 1.40 | Confirmed | Volatiles including water vapour and oxygen | High | 0.446 | 276 | [7] |
| K2-22b | K2-22 | M0V | 0.02 | <0.71 | Confirmed | Likely magnesium silicate dust and nitric oxide or carbon dioxide | 0.381 | 801 | [5] |
See also
Notes
- A study suggested that its atmosphere contains phosphorus monoxide and carbon dioxide in nitrogen-gas background instead[4]
