Kepler-452b
| Kepler-452b | |
|---|---|
 "Jorden 2.0" - en kunstners gengivelse af Kepler-452b | |
| Opdaget | |
| Kepler-rumteleskopet | |
| Kredsløb om Kepler-452 | |
| Halve storakse | 1,05 AU km |
| Excentricitet | 0,01671022 |
| Synodisk periode | - |
| Fysiske egenskaber | |
| Diameter | 1.11 (± 0.15-0.09)[1] |
| Masse | 5 ±2M⊕ kg |
| Massefylde | 10.4 ± 14.6/-4.0 kg/m³ |
| Tyngdeacc. v. ovfl. | 18.4± 17.1/-9.4 m/s² |
| Nordpolens rektascension | 19h 44m 00.89s |
| Nordpolens deklination | +44° 16′ 39.2″ ° |
| Temperatur v. ovfl. | Gnsn. -8 °C Min. -21 °C Maks. +7 °C |
Kepler-452b er en exoplanet som er i kredsløb rundt om en hovedseriestjerne med spektrum G2V, ligesom vor Sol ved navn Kepler-452. Exoplaneten blev fundet af Kepler-rumteleskopet. Kepler-452 er lidt større end Solen mht. masse og dermed også lysstyrke. Opdagelsen af planeten blev offentliggjort af NASA den 23. juli 2015, og er den første som har en størrelse på niveau med Jorden og som er i kredsløb indenfor den beboelige zone af en stjerne meget ligesom Solen.[2] Det er den anden mest Jordlignende planet til dato, efter Kepler-438b.
Stjernen er ca. 1.400 lysår (430 parsec) væk fra Solsystemet; med en hastighed som New Horizons, det hurtigste rumfartøj endnu lavet af mennesket, ville det tage omkring 25,8 millioner år for at komme der til fra Jorden.[3]
Egenskaber
Et år på 452b tager 385 jordlige dage.[4] Den er ældre og større end Jorden, men ligger inden for den konservative beboelige zone af sin stjerne.[5][6] Faktisk er året 5% længere end her på Jorden, og det samme gælder afstanden fra Kepler-452b til dens stjerne.
Den har en sandsynlig en masse fem gange større end Jordens, og overfladens tyngdekraft er dobbelt så høj som Jordens, men man skal dog huske at beregninger af masse for exoplaneter kun er grove vurderinger.[5] Det er mest sandsynligt en stor "super-jord" med mange aktive vulkaner på grund af dens højere masse og tæthed. Skyerne på planeten ville være tykke og disede og sandsynligvis dække meget mere af overfladen som set fra rummet end Jorden. Kepler-452 ville næsten se identisk ud med vores egen sol som set fra overfladen.[7]
(Exo-) Planerters egenskabet er baseret på disse 7 kriterier:
- Earth Similarity Index (ESI)—Ligheden med Jorden på en skala fra 0 til 1, hvor 1 er den mest jordlige. ESI bedømmes vha. planetens radius, massefylde, undvigelseshastighed, og temperatur. Kepler-452bs betegnelse: 0,83 (Jordens: 1).
- Standard Primary Habitability (SPH)—Hvorvidt planeten er passende for vegetation (altså primære producenter) på en skala fra 0 til 1, hvor 1 er den mest beregnede for plantevækst. SPH afhænger af temperatur (og den relative luftfugtighed hvis man kender til den). Kepler-452bs betegnelse: vides endnu ikke.
- Habitable Zone Distance (HZD)—Afstand fra centeret af stjernens beboelige, bedømt så −1 repræsentere den indre rande for zonen, mens +1 repræsentere den ydre rande. HZD afhænger af luminositet og temperatur og størrelsen af planetens kredsløb. Bemærk at selvom at mange planeter har en HZD værdi tæt på Venus' (−0.93), ligesom Kepler-438b, er HZD ikke vant til at kun bestemme om en har lidt en løbsk drivhuseffekt eller ikke, og derfor bliver Kepler-458b antaget som værende en mesoplanet i stedet for en hypertermisk planet. Kepler-452bs betegnelse: -0,49 (Jordens: -0,50).
- Habitable Zone Composition (HZC)—Mål af planetens hovedsagelige sammensætning, hvor værdier tæt på nul sandsynligvis er jern-klippe-vand-blandinger. Værdier under −1 repræsentere planeter som hovedsageligt er sammensat af jern, mens værdier større end +1 repræsentere planeter som hovedsageligt består af gas. HZC afhænger af planetens masse og radius. Kepler-452bs betegnelse: vides endnu ikke.
- Habitable Zone Atmosphere (HZA)—Planetens potentiale for at opholde liv, hvor værdier på under −1 repræsentere planeter som ofte har lidt eller ingen atmosfære, og værdier over +1 repræsenterer planeter med en atmosfære som hovedsageligt består af hydrogen (f.eks. gaskæmper). Værdier mellem −1 og +1 repræsentere en planet som hovedsageligt har atmosfære som kan opholde liv, men 0 er dog ikke helt optimalt. HZA afhænger af planetens masse, radius, størrelsen, og stjernens luminositet. Kepler-452bs betegnelse: vides endnu ikke.
- Planetary Class (pClass)—Klassificerer planeter baseret på dens termiske zoner (hot, varm eller kold, hvor varm er i den beboelige zone) og masse (asteroide, Mercurian, underjordisk, Terran, superterran, neptunske og Jupiter). Kepler-452bs betegnelse: varm superterran.
- Habitable Class (hClass)—Klassificerer beboelige planeter baseret på temperatur: hypopsychroplaneter (hP) = meget koldt (< −50 °C); psychroplaneter (P) = koldt; mesoplaneter (M) = mediumtemperaturer (0–50 °C; ikke at forveksle med den anden definition af mesoplanets); thermoplanets (T) = hot; hyperthermoplanets (hT) = meget hot (> 100 °C). Mesoplaneter ville være ideelt for komplekse organismer, hvor hP og hT ville kun understøtte ekstremofile organismer. Ikke-beboelige planeter bliver givet betegnelsen 'NH'. Kepler-452bs betegnelse: mesoplanet (M).
Gallery
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Referencer
- ^ "NASA Exoplanet Archive – Confirmed Planet Overview – Kepler-452b". NASA Exoplanet Archive. 2015. Hentet 11. april 2016.
- ^ (23. juli 2015). "NASA’s Kepler Mission Discovers Bigger, Older Cousin to Earth". Pressemeddelelse. Hentet 23. juli 2015.
- ^ "NASA telescope discovers Earth-like planet in star's 'habitable zone". BNO News. 23. juli 2015. Arkiveret fra originalen 4. marts 2016. Hentet 23. juli 2015.
- ^ Overbye, Dennis (23. juli 2015). "Kepler Data Reveals What Might Be Best 'Goldilocks' Planet Yet". The New York Times. Hentet 23. juli 2015.
- ^ a b Feltman, Rachel (23. juli 2015). "Scientists discover 12 new potential Earth-like planets". The Washington Post. Hentet 23. juli 2015.
- ^ Witze, Alexandra (23. juli 2015). "NASA spies Earth-sized exoplanet orbiting Sun-like star". Nature. Hentet 23. juli 2015.
- ^ NASA Kepler press conference. 23. juli 2015.
Se også
Eksterne henvisninger
- NASA – Kepler Mission
- NASA – Kepler Discoveries – Summary Table Arkiveret 1. april 2017 hos Wayback Machine
- Habitable Exolanets Catalog ved UPR-Arecibo
Medier brugt på denne side
This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of Mercury. The habitable zone of Kepler-186 is very small compared to that of Kepler-452 or the sun because it is a much smaller, cooler star. The size and extent of the habitable zone of Kepler-452 is nearly the same as that of the sun, but is slightly bigger because Kepler-452 is somewhat older, bigger and brighter. The size of the orbit of Kepler-452b is nearly the same as that of the Earth at 1.05 AU. Kepler-452b orbits its star once every 385 days.
Forfatter/Opretter: Pyrros, Licens: CC BY-SA 4.0
Dette skema viser Kepler-452b's egenskaber baseret på en skabelon fra den engelske wikipedia.
This artist's concept compares Earth (left) to the new planet, called Kepler-452b, which is about 60 percent larger in diameter.
PIA19827: Kepler's Small Habitable Zone Planets
http://photojournal.jpl.nasa.gov/catalog/PIA19827
Of the 1,030 confirmed planets from Kepler, a dozen are less than twice the size of Earth and reside in the habitable zone of their host stars. In this diagram, the sizes of the exoplanets are represented by the size of each sphere. These are arranged by size from left to right, and by the type of star they orbit, from the M stars that are significantly cooler and smaller than the sun, to the K stars that are somewhat cooler and smaller than the sun, to the G stars that include the sun. The sizes of the planets are enlarged by 25 times compared to the stars. The Earth is shown for reference.
NASA Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.
More information about the Kepler mission is at http://www.nasa.gov/kepler.
More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov.An artist's concept depicting one possible appearance of the planet Kepler-452b, the first near-Earth-size world to be found in the habitable zone of a star that is similar to our sun.
This artist's concept depicts one possible appearance of the planet Kepler-452b, the first near-Earth-size world to be found in the habitable zone of star that is similar to our sun. The habitable zone is a region around a star where temperatures are right for water -- an essential ingredient for life as we know it -- to pool on the surface. Scientists do not know if Kepler-452b can support life or not.
What is known about the planet is that it is about 60 percent larger than Earth, placing it in a class of planets dubbed "super-Earths." While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a better than even chance of being rocky. Kepler-452b orbits its star every 385 days.
The planet's star is about 1,400 light-years away in the constellation Cygnus. It is a G2-type star like our sun, with nearly the same temperature and mass. This star is 6 billion years old, 1.5 billion years older than our sun. As stars age, they grow in size and give out more energy, warming up their planets over time.
Scientists and artists considered these facts when creating this illustration. If the planet Kepler-452b does in fact have liquid on its surface and has grown warmer due to the older age of its star, it could possibly be experiencing a runaway greenhouse effect, where oceans would begin to evaporate and contribute to increased cloud cover. This, plus other factors such as the planet's large size, was factored into the hypothetical scenario depicted in this illustration.
NASA Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.
July 23, 2015
Twelve New Small Kepler Habitable Zone Candidates
http://www.nasa.gov/ames/kepler/twelve-new-small-kepler-habitable-zone-candidates
IMAGE CAPTION:
Since Kepler launched in 2009, twelve planets less than twice the size of Earth have been discovered in the habitable zones of their stars.
FILE DESCRIPTION:
Twelve New Kepler HZ Candidates
Highlighted are 12 new planet candidates from the seventh Kepler planet candidate catalog that are less than twice the size of Earth and orbit in the stars' habitable zone—the range of distances from a star where liquid water could exist on the surface of an orbiting planet. The dark green area represents an optimistic estimate for the habitable zone, while the light green area represents a more conservative estimate for the habitable zone. The candidates are plotted as a function of the star's surface temperate on the vertical axis and by the amount of energy the planet candidate receives by its host star. Open yellow circles show new planet candidates in the seventh catalog. Open blue circles show candidates from previous catalogs. Filled-in circles represent candidates that have been confirmed as planets due to follow-up observations. Note that the new candidates tend to be around stars more similar to the sun, representing progress in finding planets that are similar to the Earth in size and temperature that orbit sun-like stars.