Astronomy:OTS 44

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Short description: Brown dwarf in the constellation Chamaeleon
OTS 44
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OTS 44 (orange crosshair) and surrounding nebulae
Observation data
Equinox J2000.0]] (ICRS)
Constellation Chamaeleon
Right ascension  11h 10m 11.5s
Declination −76° 32′ 13″
Characteristics
Spectral type M9.5±1.0[1][2]
Astrometry
Distance522–544 or 626 ly
(160–170 or 192 pc)
Details
Mass6–17 MJ, average 11.5[3] MJup
Radius3.2 or 3.6[2] RJup
Luminosity0.00126±0.00023[lower-alpha 1] – 0.0024[3] L☉
Temperature1700±100[2][3] K
Age1–6[2] Myr
Other designations
2MASS J11100934–7632178, CHSM 16658,[4] SSTgbs J1110093–763218,[4] TIC 454329342, [GMM2009] Cha I 27[4]
Database references
SIMBADdata

OTS 44 is a young, free-floating planetary-mass brown dwarf or rogue planet, located 520 to 630 light-years (160 to 192 parsecs) away in the star-forming molecular cloud Chamaeleon I in the constellation Chamaeleon. It is surrounded by a circumstellar disk of gas and dust, from which it is actively accreting mass at an approximate rate of 500 billion kilograms per second (or equivalently, 7.6×10−12 solar masses per year).[3] With an estimated age between 1 and 6 million years, OTS 44 has not existed long enough to cool down, so it glows red with a temperature of around 1,700 K (1,430 °C; 2,600 °F) and a stellar spectral type of M9.5.[2] It likely formed from the gravitational collapse of gas and dust, a similar process to how stars typically form.[5]

The disk of OTS 44 is estimated to span at least several astronomical units in radius with a flared shape—decreasing in density but increasing in vertical thickness at farther distances from the object.[3]: 2–3  OTS 44's disk contains a total estimated mass of approximately 0.1 Jupiter masses or 30 Earth masses,[3] with a small fraction of this mass constituting dust in the disk.[6][7] OTS 44's disk will eventually coalesce to form a planetary system, with enough mass to potentially create one small gas giant planet and several Earth-sized rocky planets.[8][9]

Discovery

OTS 44 was discovered in images taken on 1–3 March 1996 by Japanese astronomers Yumiko Oasa, Motohide Tamura, and Koji Sugitani, during a search for young stellar objects and brown dwarfs in the core of the Chamaeleon I molecular cloud.[10]: 338  The discovery images were taken with the Cerro Tololo Inter-American Observatory's 1.5-metre (4.9 ft) telescope in Chile, which was equipped with the J, H, and K filters to measure the near-infrared colors of these objects.[11]: 1095 [10]: 338–339  The discoverers found 61 near-infrared-emitting objects and included them in their own catalogue,[10]: 339  which became known as the Oasa–Tamura–Sugitani (OTS) catalogue.[12][1]: 565 

OTS 44 was the 44th object and one of the dimmest objects listed in the OTS catalogue.[10]: 337 [1]: 565  The discoverers identified OTS 44 as a brown dwarf candidate because it appeared much dimmer and redder than other young stars in Chameleon I, which meant that it should have a very low mass if it shared the same age as these stars.[11]: 1046 [10]: 341  The discoverers published their analysis and identification of OTS 44 as a brown dwarf candidate in the journal Science in November 1998.[11]

In November 2004, Kevin L. Luhman, Dawn E. Peterson, and S. Thomas Megeath announced the confirmation of OTS 44 as a low-mass brown dwarf.[13] Using spectroscopic observations by the Gemini South telescope from March 2004, the researchers determined that OTS 44's mass lay close to the ~0.012 solar mass (13 Jupiter mass) boundary between giant planets and brown dwarfs, which made OTS 44 one of the least massive free-floating brown dwarfs confirmed at the time.[1][14]: L53 

Location and age

The Chamaeleon complex photographed in far infrared by the IRAS satellite. OTS 44 is located in the Chamaeleon I region.

OTS 44 is located in the constellation Chamaeleon at a declination of approximately 76.5° south of the celestial equator.[4] It is situated within the core of Chamaeleon I, one of the three major star-forming molecular clouds of the Chamaeleon complex.[11][10] Chamaeleon I is one of the nearest star-forming regions to the Sun,[10]: 336  at an estimated distance of either 160–170 parsecs (520–550 light-years) (according to 1999 parallax measurements by the Hipparcos satellite[15]: 580 [1]: 565 ) or 192 pc (630 ly) (according to 2018 parallax measurements by the Gaia satellite[16]: 565 ). Astronomers assume that OTS 44 lies at the same distance as Chamaeleon I.[6]: 2 [16]: 565 

As a member of Chamaeleon I, OTS 44 is inferred to share the same age as other young stellar objects in the region, which are known to be between 1 and 6 million years old.[2]: 13, 19  At this age, substellar objects like OTS 44 are hot and luminous.[2]: 1–2  Observations of active accretion around OTS 44 indicate that it formed in a similar process to how stars form—via direct gravitational collapse of concentrated gas and dust.[5]: 1019–1020  OTS 44 will gradually cool and contract over time—becoming an L-type brown dwarf at about 10 million years of age, and then a Y dwarf after 1 billion years of age.[5]: 1024 

Physical characteristics

The near-infrared spectrum of OTS 44 (black) shows deep absorption bands due to steam (H2O vapor) in its atmosphere. The spectrum of the M8-type brown dwarf CHSM 17173 (red) is shown for comparison.[1]

The near-infrared spectrum of OTS 44 exhibits deep absorption bands caused by steam (water vapor) in its atmosphere, indicating a relatively cool temperature corresponding to a late spectral type of M9.5±1.0.[1] Additional substances including elemental sodium (Na), potassium (K), iron hydride (FeH), and carbon monoxide (CO) have been spectroscopically detected in OTS 44's atmosphere.[2]: 4, 7, 10  OTS 44 is estimated to have an effective temperature of 1,700 ± 100 K (1,427 ± 100 °C; 2,600 ± 180 °F), based on spectral energy distribution modeling with the object's atmospheric dust taken into account.[3]: 2 [2]: 17  OTS 44 stands out from cool main-sequence stars and red giants because it is much redder and brighter in near-infrared.[10]: 339–340  Extinction by foreground dust has been observed to cause additional reddening in OTS 44's near-infrared colors (0.3±0.3-magnitude dimming in J-band),[1]: 567  but not in its optical colors.[2]: 3 

OTS 44 is a dim object with a luminosity between 0.001 and 0.002 times that of the Sun.[3]: 2 [lower-alpha 1] As a young and hot object, OTS 44 is expected to have a radius larger than that of Jupiter.[2]: 1, 19, 23  A Stefan–Boltzmann law calculation using OTS 44's luminosity and temperature suggests a "semi-empirical" radius of 3.5+0.6
−0.5 RJ, whereas a spectral energy distribution fit with OTS 44's disk taken into account suggests a radius between 3.2 and 3.6 RJ.[2]: 15, 17, 19  OTS 44 is estimated to be 6–17 times more massive than Jupiter,[6] though it is more likely below 13 Jupiter masses—in the planetary mass range, where it cannot fuse deuterium unlike brown dwarfs.[2] Hence, astronomers have also categorized OTS 44 as a free-floating planet.[5][6]

Circumstellar disk

Cross-section diagram of the OTS 44's flared disk model proposed by Joergens et al. (2013)[3]
An artist's concept of OTS 44's dust disk

In February 2005, a team of astronomers led by Kevin Luhman announced the discovery of a circumstellar disk around OTS 44.[9][8] Their discovery was based on the Spitzer Space Telescope's detection of excess mid-infrared thermal emission from OTS 44, which indicated the presence of warm dust surrounding the object.[14] As one of the least massive free-floating objects known at the time, OTS 44 claimed the record for the least massive object known to have a circumstellar disk and demonstrated that such disks could exist around planetary-mass objects.[14]

Estimates based on OTS 44's spectral energy distribution (SED) suggests that its disk contains a total mass of about 30 Earth masses.[3] Observations with the SINFONI spectrograph at the Very Large Telescope show that OTS 44 is accreting matter from its disk at the rate of approximately 10−11 of the mass of the Sun per year.[3] It could eventually develop into a planetary system.[17]

Observations with ALMA detected OTS 44's disk in millimeter wavelengths. The observations constrained the dust mass of the disk between 0.07 and 0.63 M⊕, but these mass estimates are limited by assumptions on poorly constrained parameters.[6] Another work estimates the dust mass to 0.064 M⊕ (5.2 Template:Lunar mass) for dust particles of 1 mm in size and 0.295 M⊕ (24 Template:Lunar mass) for dust particles of 1 μm in size.[16]

See also

Other free-floating rogue planets and brown dwarfs with protoplanetary disks:

  • Cha 110913-773444, rogue planet or brown dwarf surrounded by what appears to be a dusty disk
  • Cha 1107−7626, a young rogue planet that underwent an episode of rapid accretion of material from its disk
  • 2MASS J11151597+1937266, a young rogue planet or brown dwarf actively accreting material from its disk
  • KPNO-Tau 12, another young rogue planet or brown dwarf that is actively accreting material from its disk
  • J1407b, a possible disked object thought to have transited the star V1400 Centauri

Notes

  1. ↑ 1.0 1.1 In Table of 8 of Bonnefoy et al. (2014), OTS 44's effective luminosity is given as a base 10 logarithm: −2.90±0.08. The luminosity of 0.00126±0.00023 L☉ can be obtained by taking 10 to the power of the aforementioned logarithm value; the uncertainty is calculated via propagation of error.[2]: 19 

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Luhmann, K. L.; Peterson, D. E.; Megeath, S. T. (2004). "Spectroscopic Confirmation of the Least Massive Known Brown Dwarf in Chamaeleon". The Astrophysical Journal 617 (1): 565–568. doi:10.1086/425228. Bibcode: 2004ApJ...617..565L. 
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 Bonnefoy, M.; Chauvin, G.; Lagrange, A.-M.; Rojo, P.; Allard, F.; Pinte, C.; Dumas, C.; Homeier, D. (2014). "A library of near-infrared integral field spectra of young M-L dwarfs". Astronomy & Astrophysics 562 (127): A127. doi:10.1051/0004-6361/201118270. Bibcode: 2014A&A...562A.127B. 
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Joergens, V.; Bonnefoy, M.; Liu, Y.; Bayo, A.; Wolf, S.; Chauvin, G.; Rojo, P. (2013-10-01). "OTS 44: Disk and accretion at the planetary border". Astronomy and Astrophysics 558: L7. doi:10.1051/0004-6361/201322432. ISSN 0004-6361. Bibcode: 2013A&A...558L...7J. 
  4. ↑ 4.0 4.1 4.2 4.3 "OTS 44". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=OTS+44. 
  5. ↑ 5.0 5.1 5.2 5.3 Joergens, V.; Bonnefoy, M.; Liu, Y.; Bayo, A.; Wolf, S. (January 2015). "The Coolest 'Stars' are Free-Floating Planets". 18th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun. 18. Lowell Observatory. pp. 1019–1026. Bibcode: 2015csss...18.1019J. http://www2.lowell.edu/workshops/coolstars18/articles/121-Joergens+_CS18.pdf. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Bayo, AmeliaExpression error: Unrecognized word "etal". (May 2017). "First Millimeter Detection of the Disk around a Young, Isolated, Planetary-mass Object" (in en). Astrophysical Journal Letters 841 (1): L11. doi:10.3847/2041-8213/aa7046. ISSN 0004-637X. Bibcode: 2017ApJ...841L..11B. 
  7. ↑ Bayo, Amelia; Joergens, Viki; Liu, Yao; Brauer, Robert; Olofsson, Johan; Arancibia, Javier (May–June 2018). "Modeling of the Disk around a Young, Isolated, Planetary-mass Object". Frontier Research in Astrophysics - III. Mondello (Palermo), Italy. doi:10.22323/1.331.0070. Bibcode: 2019frap.confE..70B. https://eprints.whiterose.ac.uk/id/eprint/153287/1/FRAPWS2018_070.pdf. 
  8. ↑ 8.0 8.1 "Tiny Brown Dwarf's Disk May Form Miniature Solar System". Center for Astrophysics. Harvard University. 2005-02-07. https://www.cfa.harvard.edu/news/tiny-brown-dwarfs-disk-may-form-miniature-solar-system. Retrieved 2025-12-07. 
  9. ↑ 9.0 9.1 "Astronomers Discover Beginnings of 'Mini' Solar System". Spitzer Space Telescope. Jet Propulsion Laboratory. 2005-02-07. https://www.spitzer.caltech.edu/news/ssc2005-06-astronomers-discover-beginnings-of-mini-solar-system. Retrieved 2025-12-07. 
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 Oasa, Yumiko; Tamura, Motohide; Sugitani, Koji (November 1999). "A Deep Near-Infrared Survey of the Chamaeleon I Dark Cloud Core". The Astrophysical Journal 526 (1): 336–343. doi:10.1086/307964. Bibcode: 1999ApJ...526..336O. 
  11. ↑ 11.0 11.1 11.2 11.3 Tamura, Motohide; Itoh, Yoichi; Oasa, Yurniko; Nakajima, Tadashi (November 1998). "Isolated and Companion Young Brown Dwarfs in the Taurus and Chamaeleon Molecular Clouds". Science 282 (5391): 1095–1097. doi:10.1126/science.282.5391.1095. PMID 9804541. Bibcode: 1998Sci...282.1095T. 
  12. ↑ "Dictionary of Nomenclature of Celestial Objects". SIMBAD. Centre de Données astronomiques de Strasbourg. 2025-12-19. https://cds.unistra.fr/cgi-bin/Dic-Simbad?OTS. 
  13. ↑ "Strong spectral signatures of steam betray low mass brown dwarf using GNIRS at Gemini South". NOIRLab. 2004-11-30. https://noirlab.edu/public/announcements/geminiann04018/. Retrieved 2025-12-23. 
  14. ↑ 14.0 14.1 14.2 Luhman, K. L. et al. (February 2005), "Spitzer Identification of the Least Massive Known Brown Dwarf with a Circumstellar Disk", The Astrophysical Journal 620 (1): L51–L54, doi:10.1086/428613, Bibcode: 2005ApJ...620L..51L 
  15. ↑ Bertout, C.; Robichon, N.; Arenou, F. (December 1999). "Revisiting Hipparcos data for pre-main sequence stars". Astronomy & Astrophysics 352: 574–586. Bibcode: 1999A&A...352..574B. https://articles.adsabs.harvard.edu/pdf/1999A%26A...352..574B. 
  16. ↑ 16.0 16.1 16.2 Wu, Ya-Lin; Bowler, Brendan P.; Sheehan, Patrick D.; Close, Laird M.; Eisner, Joshua A.; Best, William M. J.; Ward-Duong, Kimberly; Zhu, Zhaohuan et al. (2022-05-01). "ALMA Discovery of a Disk around the Planetary-mass Companion SR 12 c". The Astrophysical Journal 930 (1): L3. doi:10.3847/2041-8213/ac6420. ISSN 0004-637X. Bibcode: 2022ApJ...930L...3W. 
  17. ↑ "Blurring the lines between stars and planets: Lonely planets offer clues to star formation". Max Planck Institute for Astronomy. 2013-10-09. http://www.mpia.de/Public/menu_q2e.php?Aktuelles/PR/2013/PR_2013_09/PR_2013_09_en.html. Retrieved 2014-09-01. 



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