Astronomy:2M1510

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2M1510 (full designation: 2MASS J15104761–2818234) is a triple or possibly quadruple system of gravitationally bound brown dwarfs, consisting of the eclipsing binary 2M1510AB and the wide companion 2M1510C.[1][2] 2M1510AB was found to be an eclipsing binary in the first light data of the SPECULOOS telescopes. It is only the second eclipsing binary brown dwarf found so far (as of March 2020), the other is 2M0535-05. The system verified theoretical models for how brown dwarfs cool. The system is located 120 light-years away from Earth in the constellation Libra.[3]

Nomenclature

Different works by different teams did give the individual brown dwarfs different names. Triaud et al.[1] used lower cases to describe the inner eclipsing binary, which is common practice. Planets do however also use lower cases. To avoid confusion this article will use the naming used by Baycroft et al.[2] and will call the direct imaging candidate by Calissendorff et al.[4] with a D.

Gizis 2002[5] 2MASSW J1510478-281817 2MASSW J1510476-281823
publication direct imaging companion eclipsing binary pair exoplanet wide companion
Calissendorff et al. 2019[4] 2M1510B – – –
Triaud et al. 2020[1] – 2M1510Aab – 2M1510B
Baycroft et al. 2025[2] – 2M1510AB 2M1510(AB)b 2M1510C
2M1510 article 2M1510D 2M1510AB 2M1510(AB)b 2M1510C

Age

2M1510AB has hydrogen-alpha emission lines, which is interpreted as a sign of youth.[5] The system also belongs to the 45±5 million-year-old Argus moving group[6] and the brown dwarfs have a low surface gravity, which is an additional indicator for youth.[1]

The brown dwarf system

A light curve for 2M1510, adapted from Triaud et al. (2020)[1]

2M1510AB and 2M1510C are separated by 250 astronomical units, making them a resolved binary in 2MASS data. The components of the inner eclipsing binary are called 2M1510A and 2M1510B. 2M1510AB is not only an eclipsing binary, but also a double-lined spectroscopic binary. This was discovered by follow-up observations with Keck II. Follow-up observations with Keck II and the VLT UT2 showed that 2M1510A and 2M1510B have very similar masses, something that is called a near equal-mass binary. 2M1510A has a mass of about 40 MJ and 2M1510B has a mass of about 39 MJ. The pair orbits each other every 20.9 days.[1] Additionally the 2M1510AB source has an elongated point spread function in VLT/SINFONI data. The naming of the brown dwarfs in Calissendorff et al. 2019 does not follow other works and the companion was called 2M1510B (here from now on: 2M1510D). 2M1510D has a mass of 17.68+4.20
−2.10 MJ and it is separated by about 4.4 au from 2M1510AB and orbits the eclipsing binary each 30 years.[4] This result was not considered by Triaud et al. 2020 and it could represent a contamination of the eclipsing binary, making a test of the cooling models more challenging.

The orbital period was improved with TESS, which will make follow-up observations with other telescopes possible.[7]

Planet candidate

Orbit of the planet (orange orbit) around the brown dwarf binary 2M1510AB (blue orbits).

In April 2025 astronomers using ESO's UVES instrument on the Very Large Telescope announced strong evidence for a circumbinary planet orbiting the brown dwarf pair 2M1510AB. The planet is called 2M1510(AB)b, or just 2M1510b. The orbit of the planet is unusual as it is a polar orbit around a binary system, the first such case that was discovered. The discovery was made with the help of radial velocity measurements that showed retrograde apsidal precession of the brown dwarf pair, which could not be explained by the outer companion. There is currently a dependency between orbital period and mass of the planet. The planet could have an orbital period of ≈100 days for a planet mass of ≈10 M⊕, but if the orbital period is instead ≈400 days, the planet mass would be ≈100 M⊕. Follow-up observations are suggested, such as eclipse timing variation (ETV) or astrometry. These could confirm the planet and break the dependence between orbital period and mass of the planet. Direct imaging would not be sensitive enough to detect 2M1510b, but could detect other planets.[8][2]

A study from 2025 did find that a timing offset in the Doppler data may have produced a spurious signal. They find radial velocity uncertainties are underestimated and the planet candidate may be a false positive.[7]

The 2M1510 planetary system
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b (unconfirmed) — — 20.897782 ± 0.000036 0.309 88.47±0.03° —

Template:Orbitbox planet end

See also

  • List of nearby stellar associations and moving groups
  • W2150AB another wide binary

other triple brown dwarf systems:

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Triaud, Amaury H. M. J.; Burgasser, Adam J.; Burdanov, Artem; Kunovac Hodžić, Vedad; Alonso, Roi; Bardalez Gagliuffi, Daniella; Delrez, Laetitia; Demory, Brice-Olivier et al. (January 2020). "An Eclipsing Substellar Binary in a Young Triple System discovered by SPECULOOS" (in en). Nature Astronomy 4 (7): 650–657. doi:10.1038/s41550-020-1018-2. Bibcode: 2020NatAs...4..650T. 
  2. ↑ 2.0 2.1 2.2 2.3 Baycroft, Thomas A.; Sairam, Lalitha; Triaud, Amaury H. M. J.; Correia, Alexandre C. M. (2025-04-16). "Evidence for a polar circumbinary exoplanet orbiting a pair of eclipsing brown dwarfs". Science Advances 11 (16). doi:10.1126/sciadv.adu0627. Bibcode: 2025SciA...11..627B. https://www.science.org/doi/10.1126/sciadv.adu0627. 
  3. ↑ "Astronomers Catch Rare Eclipse of a Double Brown Dwarf System – W. M. Keck Observatory". 9 March 2020. http://www.keckobservatory.org/speculoos/. 
  4. ↑ 4.0 4.1 4.2 Calissendorff, Per; Janson, Markus; Asensio-Torres, Rubén; Köhler, Rainer (July 2019). "Spectral characterization of newly detected young substellar binaries with SINFONI" (in en). Astronomy & Astrophysics 627: A167. doi:10.1051/0004-6361/201935319. ISSN 0004-6361. Bibcode: 2019A&A...627A.167C. 
  5. ↑ 5.0 5.1 Gizis, John E. (August 2002). "Brown Dwarfs and the TW Hydrae Association" (in en). The Astrophysical Journal 575 (1): 484–492. doi:10.1086/341259. ISSN 0004-637X. Bibcode: 2002ApJ...575..484G. 
  6. ↑ Gagné, Jonathan; Faherty, Jacqueline K.; Cruz, Kelle L.; Lafreniére, David; Doyon, René; Malo, Lison; Burgasser, Adam J.; Naud, Marie-Eve et al. (August 2015). "BANYAN. VII. A New Population of Young Substellar Candidate Members of Nearby Moving Groups from the BASS Survey" (in en). The Astrophysical Journal Supplement Series 219 (2): 33. doi:10.1088/0067-0049/219/2/33. ISSN 0067-0049. Bibcode: 2015ApJS..219...33G. 
  7. ↑ 7.0 7.1 Millward, Seb T.; Kunovac, Vedad (2025). "A new photometric ephemeris for the 2M1510 AB double brown dwarf eclipsing binary system". arXiv:2510.14801 [astro-ph.SR].
  8. ↑ information@eso.org. ""Big surprise": astronomers find planet in perpendicular orbit around pair of stars" (in en). https://www.eso.org/public/news/eso2508/. 

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