Editing Brown dwarf (section)

==== Current IAU standard ====
Currently, the [[International Astronomical Union]] considers an object above {{Jupiter mass|13}} (the limiting mass for thermonuclear fusion of deuterium) to be a brown dwarf, whereas an object under that mass (and orbiting a star or stellar remnant) is considered a planet. The minimum mass required to trigger sustained hydrogen burning (about {{Jupiter mass|80}}) forms the upper limit of the definition.<ref name="Wethington"/><ref>{{cite web |title=Working Group on Extrasolar Planets: Definition of a "Planet" |website=IAU position statement |date=2003-02-28 |url=http://home.dtm.ciw.edu/users/boss/definition.html |access-date=2014-04-28 |archive-url=https://web.archive.org/web/20141216075559/http://home.dtm.ciw.edu/users/boss/definition.html |archive-date=2014-12-16 |url-status=dead }}</ref>

It is also debated whether brown dwarfs would be better defined by their formation process rather than by theoretical mass limits based on nuclear fusion reactions.<ref name="PT-June2008">{{cite journal |last=Burgasser |first=Adam J. |date=June 2008 |title=Brown dwarfs: Failed stars, super Jupiters |url=http://astro.berkeley.edu/~gmarcy/astro160/papers/brown_dwarfs_failed_stars.pdf |url-status=dead |journal=[[Physics Today]] |location=Cambridge, MA |publisher=Massachusetts Institute of Technology |volume=61 |issue=6 |pages=70–71 |bibcode=2008PhT....61f..70B |doi=10.1063/1.2947658 |archive-url=https://web.archive.org/web/20130508182012/http://astro.berkeley.edu/~gmarcy/astro160/papers/brown_dwarfs_failed_stars.pdf |archive-date=May 8, 2013 |access-date=March 31, 2022 |via=American Institute of Physics}}</ref> Under this interpretation brown dwarfs are those objects that represent the lowest-mass products of the [[star formation]] process, while planets are objects formed in an [[accretion disk]] surrounding a star. The coolest free-floating objects discovered, such as [[WISE 0855]], as well as the lowest-mass young objects known, like [[PSO J318.5−22]], are thought to have masses below {{Jupiter mass|13}}, and as a result are sometimes referred to as [[planetary-mass object]]s due to the ambiguity of whether they should be regarded as [[rogue planets]] or brown dwarfs. There are planetary-mass objects known to orbit brown dwarfs, such as [[2M1207b]], [[2MASS J044144b]] and [[CFHTWIR-Oph 98 b|Oph 98 B]].

The 13-Jupiter-mass cutoff is a rule of thumb rather than a quantity with precise physical significance. Larger objects will burn most of their deuterium and smaller ones will burn only a little, and the 13{{Non breaking hyphen}}Jupiter-mass value is somewhere in between.<ref name=bodenheimer2013>{{cite journal |last1=Bodenheimer |first1=Peter |last2=D'Angelo |first2=Gennaro |last3=Lissauer |first3=Jack J. |author-link3=Jack J. Lissauer |last4=Fortney |first4=Jonathan J. |last5=Saumon |first5=Didier |title=Deuterium Burning in Massive Giant Planets and Low-mass Brown Dwarfs Formed by Core-nucleated Accretion |journal=The Astrophysical Journal |date=2013 |volume=770 |issue=2 |pages=120 (13 pp.) |doi=10.1088/0004-637X/770/2/120 |arxiv=1305.0980 |bibcode=2013ApJ...770..120B|s2cid=118553341 }}</ref> The amount of deuterium burnt also depends to some extent on the composition of the object, specifically on the amount of [[helium]] and [[deuterium]] present and on the fraction of heavier elements, which determines the atmospheric opacity and thus the radiative cooling rate.<ref name=Spiegel2011>{{cite journal |last1=Spiegel |first1=David S. |last2=Burrows |first2=Adam |last3=Milson |first3=John A. |title=The Deuterium-Burning Mass Limit for Brown Dwarfs and Giant Planets |journal=The Astrophysical Journal |volume=727 |issue=1 |page=57 |date=2011 |doi=10.1088/0004-637X/727/1/57 |arxiv=1008.5150 |bibcode=2011ApJ...727...57S|s2cid=118513110 }}</ref>

As of 2011 the [[Extrasolar Planets Encyclopaedia]] included objects up to 25 Jupiter masses, saying, "The fact that there is no special feature around {{Jupiter mass|13|jup=y}} in the observed mass spectrum reinforces the choice to forget this mass limit".<ref>{{cite journal |last1=Schneider |first1=Jean |last2=Dedieu |first2=Cyril |last3=Le Sidaner |first3=Pierre |last4=Savalle |first4=Renaud |last5=Zolotukhin |first5=Ivan |title=Defining and cataloging exoplanets: The exoplanet.eu database |date=2011 |volume=532 |issue=79 |journal=[[Astronomy & Astrophysics]] |arxiv=1106.0586 |doi=10.1051/0004-6361/201116713 |pages=A79 |bibcode=2011A&A...532A..79S |s2cid=55994657 }}</ref> As of 2016, this limit was increased to 60 Jupiter masses,<ref>{{cite book |last=Schneider |first=Jean |arxiv=1604.00917 |chapter=Exoplanets versus brown dwarfs: the CoRoT view and the future |title=The CoRoT Legacy Book |date=July 2016 |page=157 |doi=10.1051/978-2-7598-1876-1.c038 |isbn=978-2-7598-1876-1|s2cid=118434022 }}</ref> based on a study of mass–density relationships.<ref>{{cite journal |arxiv=1506.05097 |last1=Hatzes |first1=Artie P. |author-link1=Artie P. Hatzes |last2=Rauer |first2=Heike |author-link2=Heike Rauer |title=A Definition for Giant Planets Based on the Mass-Density Relationship |year=2015 |doi=10.1088/2041-8205/810/2/L25 |volume=810 |issue=2 |journal=The Astrophysical Journal |page=L25 |bibcode=2015ApJ...810L..25H |s2cid= 119111221 }}</ref>

The [[Exoplanet Data Explorer]] includes objects up to 24 Jupiter masses with the advisory: "The 13 Jupiter-mass distinction by the IAU Working Group is physically unmotivated for planets with rocky cores, and observationally problematic due to the [[Minimum mass|sin i ambiguity]]."<ref name="eod">{{cite journal |arxiv=1012.5676 |title=The Exoplanet Orbit Database |date=2010 |bibcode=2011PASP..123..412W |doi=10.1086/659427 |volume=123 |issue=902 |journal=[[Publications of the Astronomical Society of the Pacific]] |pages=412–422 |last1=Wright |first1=Jason T. |last2=Fakhouri |first2=Onsi |last3=Marcy |first3=Geoffrey W. |author-link3=Geoffrey Marcy |last4=Han |first4=Eunkyu |last5=Feng |first5=Y. Katherina |last6=Johnson |first6=John Asher |author-link6=John Johnson (astronomer) |last7=Howard |first7=Andrew W. |last8=Fischer |first8=Debra A. |author-link8=Debra Fischer |last9=Valenti |first9=Jeff A. |last10=Anderson |first10=Jay |last11=Piskunov |first11=Nikolai |s2cid=51769219 }}</ref> The [[NASA Exoplanet Archive]] includes objects with a mass (or minimum mass) equal to or less than 30 Jupiter masses.<ref>[http://exoplanetarchive.ipac.caltech.edu/docs/exoplanet_criteria.html Exoplanet Criteria for Inclusion in the Archive], NASA Exoplanet Archive</ref>