Sub-brown dwarf

<h2 id="description">Description</h2>
<p>Sub-brown dwarfs are formed in the manner of <a href="/facts/Star/PFbd6ICx">stars</a>, through the collapse of a <a href="/facts/Nebula/hG6coklY">gas cloud</a> (perhaps with the help of <a href="/facts/Photo-erosion/rxvuFDIu">photo-erosion</a>) but there is no consensus amongst astronomers on whether the formation process should be taken into account when classifying an object as a planet.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> Free-floating sub-brown dwarfs can be observationally indistinguishable from rogue planets, which originally formed around a star and were ejected from orbit. Similarly, a sub-brown dwarf formed free-floating in a star cluster may be captured into orbit around a star, making distinguishing sub-brown dwarfs and large planets also difficult. A definition for the term "sub-brown dwarf" was put forward by the <a href="/facts/IAU_Working_Group_on_Extra-Solar_Planets/GMFPImXo">IAU Working Group on Extra-Solar Planets</a> (WGESP), which defined it as a free-floating body found in young star clusters below the lower mass cut-off of brown dwarfs.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>
<h3>Lower mass limit</h3>
<p>The smallest mass of gas cloud that could collapse to form a sub-brown dwarf is about 1 <a href="/facts/Jupiter_mass/EtLUmeEN">Jupiter mass</a> (MJ).<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> This is because to collapse by <a href="/facts/Gravity/bqAN7DdQ">gravitational</a> contraction requires radiating away energy as heat and this is limited by the opacity of the gas.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> A 3 MJ candidate is described in a 2007 paper.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
</p>
<h2 id="list-of-possible-sub-brown-dwarfs">List of possible sub-brown dwarfs</h2>
<h3>Orbiting one or more stars</h3>
<p>There is no consensus whether these companions of stars should be considered sub-brown dwarfs or planets. Some authors agree these objects should be considered sub-brown dwarfs, since they likely formed on their own, like a "failed star".<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
</p>
<ul><li><a href="/facts/2MASS_J0441%252B2301/5o0bDwRL">2MASS J0441+2301 Bb</a></li></ul>
<p>Nonetheless, the <a href="/facts/IAU/GMFPImXo">IAU</a> working definition of an exoplanet ignored formation mechanism as a criterion, and based on it these objects would be considered planets.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a>
</p>
<ul><li><a href="/facts/WD_0806-661/UF3kklQL">WD 0806-661</a> B</li>
<li><a href="/facts/HD_106906_b/llcp5Tcg">HD 106906 b</a></li>
<li><a href="/facts/ROXs_42Bb/srnB3BY4">ROXs 42Bb</a></li></ul>
<h3>Orbiting a brown dwarf</h3>
<p>At around 2022 the IAU working definition of an exoplanet excludes these objects as planets.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> The only fitting label would be as sub-brown dwarfs, but they are more often referred as <a href="/facts/Planetary-mass_object/rbPjE6Bx">planetary mass objects</a>. Other definitions, like from the <a href="/facts/NASA_Exoplanet_Archive/DzzwL3Qe">NASA Exoplanet Archive</a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> would include these as exoplanets. There is no consensus whether these companions of brown dwarfs should be considered sub-brown dwarfs or planets.
</p>
<h4>WISE J0336−0143B</h4>
<p class="note">Main article: <a href="/facts/WISE_J0336%25E2%2588%25920143/56UczKQ5">WISE J0336−0143</a></p>
<p>WISE J0336−0143B, orbits a brown dwarf or sub-brown dwarf. The primary has a mass of 8.5 to 18 MJ and secondary has a mass of 5-11.5 MJ. This object does not fit the IAU working definition of an <a href="/facts/Exoplanet/zjfmqfUf">exoplanet</a>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> This definition requires a mass ratio of about q<0.04, but the mass ratio of WISE J0336−0143AB is q=0.61±0.05.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> It also does not fit the definition of a <a href="/facts/Rogue_planet/3t9nlDVa">rogue planet</a>, because it is gravitationally bound to a brown dwarf (or possibly sub-brown dwarf). It could be considered a planet according to alternative definitions, but according to the IAU it only fits the definition of sub-brown dwarf.
</p>
<h4>2M1207b</h4>
<p class="note">Main article: <a href="/facts/2M1207b/yRkY1xz0">2M1207b</a></p>
<p>2M1207b orbits around a young brown dwarf with a circumstellar disk and itself is likely surrounded by a circumstellar disk. The mass ratio is well above the upper limit of q=0.04 for exoplanets according to the IAU.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a>
</p>
<h4>Others</h4>
<p>Other examples of planetary-mass objects orbiting brown dwarfs and with MB<13 MJ and q>0.04:
</p>
<ul><li><a href="/facts/CFHTWIR-Oph_98/NtVC5u0b">CFHTWIR-Oph 98B</a>, with MB=11.6+0.4−0.8 MJ and q=0.509+0.017−0.023<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></li>
<li><a href="/facts/2MASS_J0249-0557/IQqq0MlD">2MASS J0249-0557ABc</a>, with Mc=11.6+1.3−1.0 MJ and 
  
    
      
        q
        =
        
          
            
              M
              
                c
              
            
            
              M
              
                A
                B
              
            
          
        
        =
        0.13
      
    
    {\displaystyle q={M_{c} \over M_{AB}}=0.13}
  
<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></li></ul>
<h3>Free-floating</h3>
<p>Also called <a href="/facts/Rogue_planet/3t9nlDVa">rogue planets</a>:
</p>
<ul><li><a href="/facts/WISE_0855%25E2%2580%25930714/rUeKl8Wx">WISE 0855–0714</a> 3–10 MJ about 7 light years away</li>
<li><a href="/facts/S_Ori_52/p9G7lTNt">S Ori 52</a></li>
<li><a href="/facts/UGPS_J0722%25E2%2588%25920540/5dYC6x1M">UGPS 0722-05</a> 10–25 MJ 13 light years away</li>
<li><a href="/facts/Cha_110913-773444/6aVB5c8w">Cha 110913-773444</a> 5–15 MJ 163 light years away</li>
<li><a href="/facts/CFBDSIR_2149%25E2%2588%25920403/1cPgvc8l">CFBDSIR 2149−0403</a> 4–7 MJ 130 light years away</li>
<li><a href="/facts/OTS_44/GjgwH57R">OTS 44</a> 11.5 MJ 550 light years away</li>
<li><a href="/facts/PSO_J318.5%25E2%2588%259222/8WpeoS2p">PSO J318.5−22</a> 6–8 MJ about 80 light years away</li></ul>
<h2 id="see-also">See also</h2>

Look up <i>sub-brown dwarf</i> in Wiktionary, the free dictionary.

<ul><li><a href="/facts/Brown_dwarf/fa7kr9lH">Brown dwarf</a></li>
<li><a href="/facts/Fusor_(astronomy)/nBzd34Is">Fusor (astronomy)</a></li>
<li><a href="/facts/Giant_planet/PjSfFuUF">Giant planet</a></li>
<li><a href="/facts/Hot_Jupiter/9wSFCuxk">Hot Jupiter</a></li>
<li><a href="/facts/Red_dwarf/56CMQcF0">Red dwarf</a></li>
<li><a href="/facts/Rogue_planet/3t9nlDVa">Rogue planet</a></li>
<li><a href="/facts/Substellar_object/vbaVWa7x">Substellar object</a></li>
<li><a href="/facts/List_of_planet_types/gmnHgTcy">List of planet types</a></li>
<li><a href="/facts/Lists_of_astronomical_objects/JeqARtr4">Lists of astronomical objects</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Working Group on Extrasolar Planets – Definition of a "Planet" Archived 16 September 2006 at the Wayback Machine POSITION STATEMENT ON THE DEFINITION OF A "PLANET" (IAU) <a href="http://www.dtm.ciw.edu/boss/definition.html" target="_blank">http://www.dtm.ciw.edu/boss/definition.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Delorme, P.; et al. (December 2012). "CFBDSIR2149-0403: a 4–7 Jupiter-mass rogue planet in the young moving group AB Doradus ?". Astronomy & Astrophysics. 548: A26. arXiv:1210.0305. Bibcode:2012A&A...548A..26D. doi:10.1051/0004-6361/201219984. S2CID 50935950. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Luhman, K. L. (21 April 2014). "Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun". The Astrophysical Journal Letters. 786 (2): L18. arXiv:1404.6501. Bibcode:2014ApJ...786L..18L. doi:10.1088/2041-8205/786/2/L18. S2CID 119102654. <a href="/wiki/The_Astrophysical_Journal_Letters" target="_blank">/wiki/The_Astrophysical_Journal_Letters</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>What is a Planet? Debate Forces New Definition, by Robert Roy Britt, 2 November 2000 <a href="https://web.archive.org/web/20010502150203/http://www.space.com/scienceastronomy/solarsystem/planet_confusion_001101-1.html" target="_blank">https://web.archive.org/web/20010502150203/http://www.space.com/scienceastronomy/solarsystem/planet_confusion_001101-1.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>IAU WGESP, 'Position Statement on the Definition of "Planet"', 28 February 2003 <a href="http://www.astro.iag.usp.br/~dinamica/WGEP.html" target="_blank">http://www.astro.iag.usp.br/~dinamica/WGEP.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Boss, Alan P.; Basri, Gibor; Kumar, Shiv S.; Liebert, James; Martín, Eduardo L.; Reipurth, Bo; Zinnecker, Hans (2003), "Nomenclature: Brown Dwarfs, Gas Giant Planets, and ?", Brown Dwarfs, 211: 529, Bibcode:2003IAUS..211..529B <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Scholz, Alexander; Geers, Vincent; Jayawardhana, Ray; Fissel, Laura; Lee, Eve; Lafreniere, David; Tamura, Motohide (2009), "Substellar Objects in Nearby Young Clusters (Sonyc): The Bottom of the Initial Mass Function in Ngc 1333", The Astrophysical Journal, 702 (1): 805–822, arXiv:0907.2243v1, Bibcode:2009ApJ...702..805S, doi:10.1088/0004-637X/702/1/805, S2CID 5102383 <a href="/wiki/Eve_Lee" target="_blank">/wiki/Eve_Lee</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Scholz, Aleks; Jayawardhana, Ray (2007), "Dusty disks at the bottom of the IMF", The Astrophysical Journal, 672 (1): L49 – L52, arXiv:0711.2510v1, Bibcode:2008ApJ...672L..49S, doi:10.1086/526340 <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Rodriguez, David R.; Zuckerman, B.; Melis, Carl; Song, Inseok (May 2011). "The Ultra Cool Brown Dwarf Companion of WD 0806-661B: Age, Mass, and Formation Mechanism". The Astrophysical Journal Letters. 732 (2): L29. arXiv:1103.3544. Bibcode:2011ApJ...732L..29R. doi:10.1088/2041-8205/732/2/L29. <a href="/wiki/The_Astrophysical_Journal_Letters" target="_blank">/wiki/The_Astrophysical_Journal_Letters</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Etangs, A. Lecavelier des; Lissauer, Jack J. (17 March 2022). "The IAU Working Definition of an Exoplanet". New Astronomy Reviews. 94: 101641. arXiv:2203.09520. Bibcode:2022NewAR..9401641L. doi:10.1016/j.newar.2022.101641. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>Etangs, A. Lecavelier des; Lissauer, Jack J. (17 March 2022). "The IAU Working Definition of an Exoplanet". New Astronomy Reviews. 94: 101641. arXiv:2203.09520. Bibcode:2022NewAR..9401641L. doi:10.1016/j.newar.2022.101641. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
<li id="fn:12"><p>"Exoplanet Criteria for Inclusion in the Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 19 January 2025. <a href="https://exoplanetarchive.ipac.caltech.edu/docs/exoplanet_criteria.html" target="_blank">https://exoplanetarchive.ipac.caltech.edu/docs/exoplanet_criteria.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li>
<li id="fn:13"><p>Etangs, A. Lecavelier des; Lissauer, Jack J. (17 March 2022). "The IAU Working Definition of an Exoplanet". New Astronomy Reviews. 94: 101641. arXiv:2203.09520. Bibcode:2022NewAR..9401641L. doi:10.1016/j.newar.2022.101641. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li>
<li id="fn:14"><p>Calissendorff, Per; De Furio, Matthew; Meyer, Michael; Albert, Loïc; Aganze, Christian; Ali-Dib, Mohamad; Bardalez Gagliuffi, Daniella C.; Baron, Frederique; Beichman, Charles A.; Burgasser, Adam J.; Cushing, Michael C.; Faherty, Jacqueline Kelly; Fontanive, Clémence; Gelino, Christopher R.; Gizis, John E. (1 April 2023). "JWST/NIRCam Discovery of the First Y+Y Brown Dwarf Binary: WISE J033605.05-014350.4". The Astrophysical Journal. 947 (2): L30. arXiv:2303.16923. Bibcode:2023ApJ...947L..30C. doi:10.3847/2041-8213/acc86d. ISSN 0004-637X. <a href="https://doi.org/10.3847%2F2041-8213%2Facc86d" target="_blank">https://doi.org/10.3847%2F2041-8213%2Facc86d</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li>
<li id="fn:15"><p>Luhman, K. L.; Tremblin, P.; Birkmann, S. M.; Manjavacas, E.; Valenti, J.; Alves de Oliveira, C.; Beck, T. L.; Giardino, G.; Lützgendorf, N.; Rauscher, B. J.; Sirianni, M. (1 June 2023). "JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B". The Astrophysical Journal. 949 (2): L36. arXiv:2305.18603. Bibcode:2023ApJ...949L..36L. doi:10.3847/2041-8213/acd635. ISSN 0004-637X. <a href="https://doi.org/10.3847%2F2041-8213%2Facd635" target="_blank">https://doi.org/10.3847%2F2041-8213%2Facd635</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li>
<li id="fn:16"><p>Fontanive, Clémence; Allers, Katelyn N.; Pantoja, Blake; Biller, Beth; Dubber, Sophie; Zhang, Zhoujian; Dupuy, Trent; Liu, Michael C.; Albert, Loïc (1 December 2020). "A Wide Planetary-mass Companion to a Young Low-mass Brown Dwarf in Ophiuchus". The Astrophysical Journal. 905 (2): L14. arXiv:2011.08871. Bibcode:2020ApJ...905L..14F. doi:10.3847/2041-8213/abcaf8. ISSN 0004-637X. <a href="https://doi.org/10.3847%2F2041-8213%2Fabcaf8" target="_blank">https://doi.org/10.3847%2F2041-8213%2Fabcaf8</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li>
<li id="fn:17"><p>Dupuy, Trent J.; Liu, Michael C.; Allers, Katelyn N.; Biller, Beth A.; Kratter, Kaitlin M.; Mann, Andrew W.; Shkolnik, Evgenya L.; Kraus, Adam L.; Best, William M. J. (1 August 2018). "The Hawaii Infrared Parallax Program. III. 2MASS J0249-0557 c: A Wide Planetary-mass Companion to a Low-mass Binary in the β Pic Moving Group". The Astronomical Journal. 156 (2): 57. arXiv:1807.05235. Bibcode:2018AJ....156...57D. doi:10.3847/1538-3881/aacbc2. ISSN 0004-6256. <a href="https://doi.org/10.3847%2F1538-3881%2Faacbc2" target="_blank">https://doi.org/10.3847%2F1538-3881%2Faacbc2</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li>
</ol>

Sub-brown dwarf open-in-new

Sub-brown dwarf