Starbox test
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| Radial velocity (Rv) | -1 km/s |
Methods of detecting exoplanets
editThis is a list of ways to detect exoplanets. Exoplanets are planets that orbit other stars past the Sun. Scientists have found thousands of exoplanets.
However, exoplanets are very small and they do not give off visible light like stars. So, only a few exoplanets have been found directly. Most exoplanets have been found by looking at the changes they cause on their stars.
Confirmed methods
editThese are the methods that have worked at least once, to detect a planet for the first time or after it is found.
Astrometry
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Astrometry is the science of measuring the position of a star in space over time. When planets move in orbits around stars due to the star's gravity, the star moves slightly due to the planet's gravity. So, a star with a planet orbiting it will "wobble" in a circle around the center of mass, and the star's position will keep changing.[1]
Astrometry was first used for binary stars, and it is the oldest method to find exoplanets. For example, in 1943, the astronomer Kaj Strand announced that there was a planet orbiting 61 Cygni.[2] A few more planets were claimed to be found, including several planets said to be around Lalande 21185.[3] Scientists now know that these "planets" likely do not actually exist. This is because planets only cause a very small wobble on their stars, and the shifts in the stars' positions were too small to be detected by earlier telescopes.[1]
Technology today is able to measure positions with more accuracy. A team using the Hubble Space Telescope could detect a planet around Gliese 876, but it was already discovered earlier.[4] NASA's Exoplanet Archive lists one planet found using astrometry, named DENIS-P J082303.1-491201 b.[5] Also, the Gaia spacecraft, which launched in 2013, can measure positions of stars to 10 millionths of an arcsecond, and may find tens of thousands of exoplanets.[6]
- ^ a b "Astrometry". The Planetary Society. Retrieved 13 July 2017.
- ^ Strand, K. Aa. (1943). "61 Cygni as a Triple System". Publications of the Astronomical Society of the Pacific. 55 (322): 29–32. Bibcode:1943PASP...55...29S. doi:10.1086/125484.
- ^ Gatewood, G. (1996). "Lalande 21185". Bulletin of the American Astronomical Society. 28. American Astronomical Society, 188th AAS Meeting, #40.11;: 885. Bibcode:1996AAS...188.4011G.
{{cite journal}}: CS1 maint: extra punctuation (link) - ^ Benedict; McArthur, B. E.; Forveille, T.; Delfosse, X.; Nelan, E.; Butler, R. P.; Spiesman, W.; Marcy, G.; Goldman, B.; Perrier, C.; Jefferys, W. H.; Mayor, M. (2002). "A Mass for the Extrasolar Planet Gliese 876b Determined from Hubble Space Telescope Fine Guidance Sensor 3 Astrometry and High-Precision Radial Velocities". The Astrophysical Journal Letters. 581 (2): L115–L118. arXiv:astro-ph/0212101. Bibcode:2002ApJ...581L.115B. doi:10.1086/346073.
{{cite journal}}: Unknown parameter|displayauthors=ignored (|display-authors=suggested) (help) - ^ "NASA Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 19 May 2017.
- ^ "Exoplanets". Gaia - ESA Science & Technology. 9 February 2017. Retrieved 13 July 2017.
Phylogeny
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Planetary nebulae to add
edit- ^ Tahon, Guillaume; Tytgat, Bjorn; Lebbe, Liesbeth; Carlier, Aurélien; Willems, Anne (2018). "Abditibacterium utsteinense sp. nov., the first cultivated member of candidate phylum FBP, isolated from ice-free Antarctic soil samples". Systematic and Applied Microbiology. 41 (4): 279–290. doi:10.1016/j.syapm.2018.01.009. PMID 29475572. S2CID 3515091.
- ^ Pavan, María Elisa; Pavan, Esteban E.; Glaeser, Stefanie P.; Etchebehere, Claudia; Kämpfer, Peter; Pettinari, María Julia; López, Nancy I. (2018). "Proposal for a new classification of a deep branching bacterial phylogenetic lineage: Transfer of Coprothermobacter proteolyticus and Coprothermobacter platensis to Coprothermobacteraceae fam. Nov., within Coprothermobacterales ord. Nov., Coprothermobacteria classis nov. And Coprothermobacterota phyl. Nov. And emended description of the family Thermodesulfobiaceae". International Journal of Systematic and Evolutionary Microbiology. 68 (5): 1627–1632. doi:10.1099/ijsem.0.002720. PMID 29595416.
- ^ Hao, Liping; McIlroy, Simon Jon; Kirkegaard, Rasmus Hansen; Karst, Søren Michael; Fernando, Warnakulasuriya Eustace Yrosh; Aslan, Hüsnü; Meyer, Rikke Louise; Albertsen, Mads; Nielsen, Per Halkjær; Dueholm, Morten Simonsen (2018). "Novel prosthecate bacteria from the candidate phylum Acetothermia". The ISME Journal. 12 (9): 2225–2237. doi:10.1038/s41396-018-0187-9. PMC 6092417. PMID 29884828.
- ^ Nobu, Masaru K.; Dodsworth, Jeremy A.; Murugapiran, Senthil K.; Rinke, Christian; Gies, Esther A.; Webster, Gordon; Schwientek, Patrick; Kille, Peter; Parkes, R John; Sass, Henrik; Jørgensen, Bo B.; Weightman, Andrew J.; Liu, Wen-Tso; Hallam, Steven J.; Tsiamis, George; Woyke, Tanja; Hedlund, Brian P. (2016). "Phylogeny and physiology of candidate phylum 'Atribacteria' (OP9/JS1) inferred from cultivation-independent genomics". The ISME Journal. 10 (2): 273–286. doi:10.1038/ismej.2015.97. PMC 4737943. PMID 26090992.
- ^ Martinez-Gutierrez, Carolina A.; Aylward, Frank O. (2021). "Phylogenetic Signal, Congruence, and Uncertainty across Bacteria and Archaea". Molecular Biology and Evolution. 38 (12): 5514–5527. doi:10.1093/molbev/msab254. PMC 8662615. PMID 34436605.
- ^ Coleman, Gareth A.; Davín, Adrián A.; Mahendrarajah, Tara A.; Szánthó, Lénárd L.; Spang, Anja; Hugenholtz, Philip; Szöllősi, Gergely J.; Williams, Tom A. (2021). "A rooted phylogeny resolves early bacterial evolution" (PDF). Science. 372 (6542). doi:10.1126/science.abe0511. PMID 33958449. S2CID 220602262.
- ^ Moody, Edmund RR; Mahendrarajah, Tara A.; Dombrowski, Nina; Clark, James W.; Petitjean, Celine; Offre, Pierre; Szöllősi, Gergely J.; Spang, Anja; Williams, Tom A. (2022). "An estimate of the deepest branches of the tree of life from ancient vertically evolving genes". eLife. 11. doi:10.7554/eLife.66695. PMC 8890751. PMID 35190025.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Wu, Dongying; et al. (2009). "A phylogeny-driven genomic encyclopaedia of Bacteria and Archaea". Nature. 462 (7276): 1056–1060. Bibcode:2009Natur.462.1056W. doi:10.1038/nature08656. PMC 3073058. PMID 20033048.
- ^ Jüttner, Michael; Ferreira-Cerca, Sébastien (2022). "Looking through the Lens of the Ribosome Biogenesis Evolutionary History: Possible Implications for Archaeal Phylogeny and Eukaryogenesis". Molecular Biology and Evolution. 39 (4). doi:10.1093/molbev/msac054. PMC 8997704. PMID 35275997.
- ^ MacLeod, Fraser; s. Kindler, Gareth; Lun Wong, Hon; Chen, Ray; p. Burns, Brendan (2019). "Asgard archaea: Diversity, function, and evolutionary implications in a range of microbiomes". AIMS Microbiology. 5 (1): 48–61. doi:10.3934/microbiol.2019.1.48. PMC 6646929. PMID 31384702.