Assumed to orbit just outside the inner edge of the habitable zone, HD 85512 b is classified as a rocky Earth-size exoplanet with a minimum mass of 3.6⊕ Earths based on which the estimated radius is 1.3⊕. Assuming a minimum surface gravity of 1.4g and an Earth-like atmosphere the estimated temperature at the top of its atmosphere could be 25°C. If the planet has roughly 50% cloud cover, water may exist in liquid form, however HD 85512 b is likely a desert planet rather than an ocean planet because of the strong stellar flux it receives from its relatively nearby host star. The planet orbits a star with 69% the solar mass and 53% the solar radius emitting about 11% of the Sun's luminosity at a distance of about 0.26AU with an orbital period of about 54.42 days, and is possibly tidally locked.
Image credit: ESO/M. Kornmesser
Planet Designation | Title | Constellation | Distance | SMA | Period | Mass | Radius | Year | |
---|---|---|---|---|---|---|---|---|---|
1 | Proxima b | Nearest Known Exoplanet | Centaurus | 4.24ly | 0.04856AU | 11.1868d | 1.27⊕ | 2016 | |
2 | Barnard b | Second Closest Known Exoplanet | Ophiuchus | 5.9ly | AU | d | 3.23⊕ | ||
3 | Epsilon Eridani b | Asteroid Belts and Controversal Planets | Eridanus | 10.48ly | 3.53AU | 2671d | 245⊕ | 2000 | |
4 | Ross 128 b | Third Closest Known Exoplanet | Virgo | 11.03ly | 0.0496AU | 9.8658d | 1.35⊕ | 2017 | |
5 | Tau Ceti e | Planets Needing Confirmation | Cetus | 11.91ly | 0.538AU | 162.87d | 3.29⊕ | 2017 | |
6 | Luyten's Star b | Only 1.2 Light-Years Away from Procyon | Canis Minor | 12.2ly | 0.091101AU | 18.6498d | 2.89⊕ | 2017 | |
7 | Kapteyn's Star c | Oldest-known Cold Exoplanet | Pictor | 12.76ly | 0.311AU | 121.54d | 4.8⊕ | 2014 | |
8 | Wolf 1061 c | Temperate Super-Earth or Super-Mars | Ophiuchus | 14.04ly | 0.089AU | 17.8719d | 3.41⊕ | 2015 | |
9 | Gliese 832 c | Large Planet as Temperate as Earth | Grus | 16.1ly | AU | d | 5.4⊕ | ||
10 | 40 Eridani b | Hot Super-Earth in Triple Star System | Eridanus | 16.26ly | 0AU | 42.378d | 8.47⊕ | 2018 | |
11 | Gliese 3323 b | Little Known in Habitable Zone | Eridanus | 17.54ly | 0.03282AU | 5.3636d | 2.02⊕ | 2017 | |
12 | LTT 1445A b | Planet in Triple Red Dwarf System | Eridanus | 22.5ly | 0.022AU | 5.35876d | 2.2⊕ | 1.18⊕ | 2019 |
13 | Gliese 667C c | Earth-like Planet in Triple Star System | Scorpius | 23.6ly | 0.125AU | 28.14d | 3.71⊕ | 2013 | |
14 | HD 85512 b | Bordering the Habitable Zone | Vela | 36.4ly | 0.26AU | 58.43d | 3.6⊕ | 2011 | |
15 | Gliese 1132 b | Heat Planet with Atmosphere | Vela | 39.3ly | 0.0153AU | 1.62893d | 1.66⊕ | 1.13⊕ | 2015 |
16 | Trappist-1 d | Small but Most Earth-like Known Planet | Aquarius | 39.5ly | 0.02227AU | 4.04922d | 0.297⊕ | 0.78⊕ | 2016 |
17 | LHS 1140 b | A Massive Super-Earth Inside Habitable Zone | Cetus | 40.67ly | 0.0946AU | 24.7372d | 6.64⊕ | 1.72⊕ | 2017 |
18 | Gliese 143 b | A Huge Neptunian Around a K-Star | Reticulum | 53.2ly | 0.1915AU | 35.6125d | 30.63⊕ | 2.61⊕ | 2019 |
19 | TOI-270 b | Nearby M-Dwarf Planets | Dorado | 73.23ly | AU | d | 1.9⊕ | ||
20 | Gliese 3470 b | Evaporating Planet | Cancer | 95.5ly | 0.0355AU | 3.33665d | 13.4⊕ | 4.57⊕ | 2012 |
21 | K2-3 b | Super-Earths Trio in Leo | Leo | 143.9ly | 0.0747AU | 10.0547d | 2.7⊕ | 2.07⊕ | 2015 |
22 | HIP 11915 b | A Twin of Jupiter | Cetus | 175ly | AU | d | 0.99⊕ | ||
23 | K2-288B b | Detected by Citizen Scientists | Taurus | 226ly | 0.164AU | 31.3935d | 4⊕ | 1.90⊕ | 2018 |
24 | Kepler-186 f | Earth-sized Cold Kepler Planet | Cygnus | 582ly | 0.432AU | 129.944d | 1.4⊕ | 1.16⊕ | 2014 |
Most of the stars introduced on this page are 'Red Dwarfs'. Actually they represent the most common type of stars. About 73% of all stars in the Milky Way galaxy are dim red dwarfs, featuring less than half the solar surface temperature and low luminosity, but in turn high stellar activity, such as flares and hazardous radiation that can hit red dwarf planets hard potentially prohibiting formation of known lifeforms.
Given its minute energy emission, the habitable zone (HBZ, an imaginary ring where temperatures support liquid water) of a red dwarf is situated near the star, as are planets orbiting inside this zone. The gravitational pull of the star can tidally lock a nearby planet which then faces one hemisphere to the star while the other is enshrouded in darkness - like the Earth moon - the axial rotation period equals the orbital period.
Some densely populated systems, such as TRAPPIST-1, have several planets orbiting in close proximity in that an observer on a planet could see other planets larger than our moon in the sky. Also, the planet may have one or multiple moons themselves. In any case a truly impressive spectacle with fast changes.
Due to their low visual luminosity no known red dwarf is visible by the naked eye, not even the nearest such as Proxima Centauri or the solitary Barnard's Star. Others, such as Gliese 667, are triple star systems but anywhere near visual magnitude
Image Credit: NASA/ESA/STScl