Editing Proplyd (section)

== Characteristics ==
[[File:Opo0113i.jpg|thumb|upright=1.5|Illustration of the dynamics of a proplyd, including an [[astrophysical jet]]]]
[[File:177-341W collage Aru et al 2024.png|thumb|upright=1.5|Components of proplyd 177-341W in the Orion Nebula observed with [[Very Large Telescope|VLT]] [[Multi-unit spectroscopic explorer|MUSE]], showing an ionization front, protoplanetary disk, and tail<ref>{{cite journal |last1=Aru |first1=Mari-Liis |last2=Mauco |first2=Karina |last3=Manara |first3=Carlo F. |title=A tell-tale tracer for externally irradiated protoplanetary disks: Comparing the [C I] 8727 Å line and ALMA observations in proplyds |journal=Astronomy & Astrophysics |volume=692 |pages=A137 |date=December 2024 |doi=10.1051/0004-6361/202451737 |url=https://www.aanda.org/articles/aa/full_html/2024/12/aa51737-24/aa51737-24.html|arxiv=2410.21018 }}</ref>]]

In the Orion Nebula the proplyds observed are usually one of two types. Some proplyds [[Photoionization|glow]] around [[Luminosity|luminous]] stars, in cases where the disk is found close to the star, glowing from the star's luminosity. Other proplyds are found at a greater distance from the host star and instead show up as dark silhouettes due to the self-obscuration of cooler dust and gases from the disk itself. Some proplyds show signs of movement from [[solar irradiance]] shock waves pushing the proplyds. The Orion Nebula is approximately 1,500 [[light-years]] from the [[Sun]] with very active [[star formation]]. The Orion Nebula and the Sun are in the same [[Orion Arm|spiral arm]] of the [[Milky Way|Milky Way galaxy]].<ref>{{Cite web|url=https://www.spacetelescope.org/news/heic0917/|title=Born in beauty: proplyds in the Orion Nebula|website=www.spacetelescope.org}}</ref><ref>{{Cite web|url=https://www.spacetelescope.org/images/opo9424b/|title=Proplyds|website=www.spacetelescope.org}}</ref><ref>{{Cite APOD |date=22 December 2009 |title=Planetary Systems Now Forming in Orion |access-date=}}</ref><ref>{{Cite APOD |date=7 December 1996 |title=Planetary Systems Now Forming in Orion |access-date=}}</ref>

A proplyd may form new [[planet]]s and [[planetesimal]] systems. Current models show that the [[metallicity]] of the star and proplyd, along with the correct planetary system temperature and distance from the star, are keys to planet and [[Nebular hypothesis|planetesimal formation]]. To date, the [[Solar System]], with 8 planets, 5 [[dwarf planet]]s and 5 planetesimal systems, is the largest [[planetary system]] found.<ref>{{Cite web|url=http://www.windows2universe.org/our_solar_system/solar_system.html|title=The Solar System: The Sun, Planets, Dwarf Planets, Moons, Asteroids, Comets, Meteors, Solar System Formation - Windows to the Universe}}</ref><ref>{{Cite web|url=https://www.universetoday.com/15451/the-solar-system/|title=Solar System Guide|first=Matt|last=Williams|date=September 5, 2015}}</ref><ref>{{Cite web|url=https://www.universetoday.com/33059/inner-planets/|title=The Inner Planets of Our Solar System|first=Matt|last=Williams|date=December 3, 2014}}</ref> Most proplyds develop into a system with no planetesimal systems, or into one very large planetesimal system.<ref>{{Cite web|url=https://sites.astro.caltech.edu/~jwang/Project4.html|title=Planet-Metallicity Correlation|website=sites.astro.caltech.edu}}</ref><ref>{{Cite journal|title=The Planet-Metallicity Correlation|first1=Debra A.|last1=Fischer|first2=Jeff|last2=Valenti|date=April 1, 2005|journal=The Astrophysical Journal|volume=622|issue=2 |pages=1102–1117|doi=10.1086/428383|bibcode=2005ApJ...622.1102F |s2cid=121872365 |doi-access=free}}</ref><ref>{{Cite journal|title=Revealing A Universal Planet-Metallicity Correlation For Planets of Different Sizes Around Solar-Type Stars|first1=Ji|last1=Wang|first2=Debra A.|last2=Fischer|date=January 1, 2015|journal=The Astronomical Journal|volume=149|issue=1|pages=14|doi=10.1088/0004-6256/149/1/14|arxiv=1310.7830|bibcode=2015AJ....149...14W |s2cid=118415186 }}</ref><ref>{{Cite web|url=http://www.astrobio.net/news-exclusive/when-stellar-metallicity-sparks-planet-formation/|work=Astrobiology Magazine |title=When Stellar Metallicity Sparks Planet Formation |first=Ray |last=Sanders |date=9 April 2012 |url-status=usurped |archive-url=https://web.archive.org/web/20201207080603/http://www.astrobio.net/news-exclusive/when-stellar-metallicity-sparks-planet-formation/ |archive-date=2020-12-07}}</ref><ref>From Lithium to Uranium (IAU S228): Elemental Tracers of Early Cosmic Evolution
By International Astronomical Union. Symposium, by Vanessa Hill, Patrick Francois, [[Francesca Primas]], page 509-511, "the G star problem"</ref><ref>{{cite journal |last1=Kokubo |first1=E. |last2=Ida |first2=S. |title=Dynamics and accretion of planetesimals |journal=Progress of Theoretical and Experimental Physics |date=30 October 2012 |volume=2012 |issue=1 |pages=1A308–0 |doi=10.1093/ptep/pts032|doi-access=free |arxiv=1212.1558 }}</ref>