Radio Emission from Ultracool Dwarfs

  • Peter K. G. WilliamsEmail author
Reference work entry


The 2001 discovery of radio emission from ultracool dwarfs (UCDs), the very low-mass stars and brown dwarfs with spectral types of ∼M7 and later, revealed that these objects can generate and dissipate powerful magnetic fields. Radio observations provide unparalleled insight into UCD magnetism: detections extend to brown dwarfs with temperatures \(\lesssim \)1000 K, where no other observational probes are effective. The data reveal that UCDs can generate strong (kG) fields, sometimes with a stable dipolar structure; that they can produce and retain nonthermal plasmas with electron acceleration extending to MeV energies; and that they can drive auroral current systems resulting in significant atmospheric energy deposition and powerful, coherent radio bursts. Still to be understood are the underlying dynamo processes, the precise means by which particles are accelerated around these objects, the observed diversity of magnetic phenomenologies, and how all of these factors change as the mass of the central object approaches that of Jupiter. The answers to these questions are doubly important because UCDs are both potential exoplanet hosts, as in the TRAPPIST-1 system, and analogues of extrasolar giant planets themselves.


Brown dwarfs Ultracool dwarfs Radio emission Magnetic activity Dynamo 


  1. Antonova A, Doyle JG, Hallinan G, Golden A, Koen C (2007) A&A 472(1):257. Scholar
  2. Antonova A, Hallinan G, Doyle JG et al (2013) A&A 549:A131. Scholar
  3. Axford WI (1969) Rev Geophys Space Phys 7:421. Scholar
  4. Basri G, Marcy GW (1995) AJ 109:762. Scholar
  5. Berger E, Ball S, Becker KM et al (2001) Natur 410:338. Scholar
  6. Berger E, Rutledge RE, Reid IN et al (2005) ApJ 627(2):960. Scholar
  7. Berger E, Basri G, Gizis JE et al (2008a) ApJ 676:1307. Scholar
  8. Berger E, Gizis JE, Giampapa MS et al (2008b) ApJ 673:1080. Scholar
  9. Berger E, Rutledge RE, Phan-Bao N et al (2009) ApJ 695:310. Scholar
  10. Berger E, Basri G, Fleming TA et al (2010) ApJ 709:332. Scholar
  11. Bhardwaj A, Gladstone GR (2000) RvGeo 38(3):295. Scholar
  12. Bouvier J, Matt SP, Mohanty S et al (2014) In: Beuther H, Klessen RS, Dullemond CP, Henning T (eds) Protostars and planets VI. University of Arizona Press, Tucson, p 433. Scholar
  13. Breuer D, Labrosse S, Spohn T (2010) SSRv 152:449. Scholar
  14. Burgasser AJ, Putman ME (2005) ApJ 626(1):486. Scholar
  15. Burgasser AJ, Melis C, Zauderer BA, Berger E (2013) ApJL 762:L3. Scholar
  16. Burgasser AJ, Melis C, Todd J et al (2015) AJ 150(6):180. Scholar
  17. Burningham B, Hardcastle M, Nichols JD et al (2016) MNRAS 463(2):2202. Scholar
  18. Chabrier G, Baraffe I (2000) ARA&A 38:337. Scholar
  19. Cook BA, Williams PKG, Berger E (2014) ApJ 785(1):10. Scholar
  20. de Pater I, Butler BJ, Green DA et al (2003) Icarus 163:434. Scholar
  21. Doyle JG, Antonova A, Marsh MS et al (2010) A&A 524:A15. Scholar
  22. Drake JJ, Stern RA, Stringfellow G et al (1996) ApJ 469:828. Scholar
  23. Dungey JW (1961) Phys Rev Lett 6(2):47. Scholar
  24. Dupuy TJ, Forbrich J, Rizzuto A et al (2016) ApJ 827(1):23. Scholar
  25. Ekenbäck A, Holmström M, Wurz P et al (2010) ApJ 709(2):670. Scholar
  26. Fleming TA, Giampapa MS, Schmitt JHMM (2000) ApJ 553:372. Scholar
  27. Forbrich J, Dupuy TJ, Reid MJ et al (2016) ApJ 827(1):22. Scholar
  28. Gagné J, Faherty JK, Burgasser AJ et al (2017) ApJL 841:1. Scholar
  29. Gastine T, Morin J, Duarte L et al (2013) A&A 549:L5. Scholar
  30. Gillon M, Jehin E, Lederer SM et al (2016) Nature 533:221. Scholar
  31. Gillon M, Triaud AHMJ, Demory BO et al (2017) Nature 542:7642. Scholar
  32. Gizis JE, Burgasser AJ, Berger E et al (2013) ApJ 779(2):172. Scholar
  33. Gizis JE, Williams PKG, Burgasser AJ et al (2016) AJ 152(5):123. Scholar
  34. Güdel M, Benz AO (1993) ApJL 405:L63. Scholar
  35. Hallinan G, Antonova A, Doyle JG et al (2006) ApJ 653:690. Scholar
  36. Hallinan G, Bourke S, Lane C et al (2007) ApJL 663:L25. Scholar
  37. Hallinan G, Antonova A, Doyle JG et al (2008) ApJ 684(1):644. Scholar
  38. Hallinan G, Littlefair S, Cotter G et al (2015) Nature 523:568. Scholar
  39. Harding LK, Hallinan G, Boyle RP et al (2013a) ApJ 779(2):101. Scholar
  40. Harding LK, Hallinan G, Konopacky QM et al (2013b) A&A 554:A113. Scholar
  41. Jaeger TR, Osten RA, Lazio TJ, Kassim N, Mutel RL (2011) AJ 142:189. Scholar
  42. Jakosky BM, Grebowsky JM, Luhmann JG, Brain DA (2015) GeoRL 42:8791. Scholar
  43. Jonas JL (2009) IEEE Proc 97(8):1522. Scholar
  44. Kao MM, Hallinan G, Pineda JS et al (2016) ApJ 818(1):24. Scholar
  45. Kirkpatrick JD, Reid IN, Liebert J et al (1999) ApJ 519(2):802. Scholar
  46. Kirkpatrick JD, Gelino CR, Cushing MC et al (2012) ApJ 753(2):156. Scholar
  47. Kochukhov O, Lavail A (2017) ApJL 835(1):L4. Scholar
  48. Kochukhov O, Petit P, Strassmeier KG et al (2017) AN 338:428. Scholar
  49. Kuznetsov AA, Doyle JG, Yu S et al (2012) ApJ 746(1):99. Scholar
  50. Leto P, Trigilio C, Oskinova L et al (2017) MNRAS 467:2820. Scholar
  51. Liebert J, Kirkpatrick JD, Reid IN, Fisher MD (1999) ApJ 519:345. Scholar
  52. Linsky JL, Wood BE, Brown A, Giampapa MS, Ambruster C (1995) ApJ 499:670. Scholar
  53. Lynch C, Mutel RL, Güdel M (2015) ApJ 802:106. Scholar
  54. Lynch C, Murphy T, Ravi V et al (2016) MNRAS 457(2):1224. Scholar
  55. Lynch CR, Lenc E, Kaplan DL, Murphy T, Anderson GE (2017) ApJL 835:30. Scholar
  56. Martín EL, Delfosse X, Basri G et al (1999) AJ 118(5):2466. Scholar
  57. McComas DJ, Bagenal F (2007) GeoRL 34(20):L20,106. Scholar
  58. McLean M, Berger E, Irwin J, Forbrich J, Reiners A (2011) ApJ 741(1):27. Scholar
  59. McLean M, Berger E, Reiners A (2012) ApJ 746(1):23. 1/23ADSGoogle Scholar
  60. Metodieva YT, Kuznetsov AA, Antonova AE et al (2017) MNRAS 465(2):1995. Scholar
  61. Miles-Páez PA, Zapatero Osorio MR, Pallé E (2015) A&A 580:L12. Scholar
  62. Miles-Páez PA, Metchev SA, Heinze A, Apai D (2017) ApJ 840:83. Scholar
  63. Mohanty S, Basri G, Shu F, Allard F, Chabrier G (2002) ApJ 571:469. Scholar
  64. Morin J, Donati JF, Petit P et al (2010) MNRAS 407(4):2269. Scholar
  65. Nichols JD, Burleigh MR, Casewell SL et al (2012) ApJ 760(1):59. Scholar
  66. Osten RA, Brown A, Ayres TR et al (2004) ApJS 153(1):317. Scholar
  67. Osten RA, Hawley SL, Bastian TS, Reid IN (2006) ApJ 637(1):518. Scholar
  68. Osten RA, Phan-Bao N, Hawley SL, Reid IN, Ojha R (2009) ApJ 700:1750. Scholar
  69. Osten RA, Melis C, Stelzer B et al (2015) ApJL 805:L3. Scholar
  70. Paty C, Paterson W, Winglee R (2008) JGR 113:A06,211. Scholar
  71. Perley RA, Chandler CJ, Butler BJ, Wrobel JM (2011) ApJL 739(1):L1. Scholar
  72. Phan-Bao N, Osten RA, Lim L, Martín EL, Ho PTP (2007) ApJ 658:553. Scholar
  73. Pineda JS, Hallinan G, Kirkpatrick JD et al (2016) ApJ 826(1):73. Scholar
  74. Ravi V, Hallinan G, Hobbs G, Champion DJ (2011) ApJL 735(1):L2. Scholar
  75. Reid IN, Kirkpatrick JD, Gizis JE, Liebert J (1999) ApJL 527(2):L105. Scholar
  76. Reiners A, Schuessler M, Passegger VM (2014) ApJ 794(2):144. Scholar
  77. Robertson P, Mahadevan S, Endl M, Roy A (2014) Sci 345(6915):440. Scholar
  78. Rodriguez LF, Zapata L, Palau A (2017) Astron J 153:209. Scholar
  79. Rodríguez-Barrera MI, Helling C, Stark CR, Rice AM (2015) MNRAS 454:3977. Scholar
  80. Route M, Wolszczan A (2012) ApJL 747(2):L22. Scholar
  81. Route M, Wolszczan A (2016) ApJL 821(2):L21. Scholar
  82. Rutledge RE, Basri G, Martín EL, Bildsten L (2000) ApJL 538:L141. Scholar
  83. Saar SH, Linsky JL (1985) ApJ 299:47. Scholar
  84. Santos-Costa D, Bolton SJ (2008) P&SS 56:326. Scholar
  85. Sault RJ, Oosterloo T, Dulk GA, Leblanc Y (1997) A&A 324:1190. Scholar
  86. Shields AL, Ballard S, Johnson JA (2016) Phys Rep 663:1. Scholar
  87. Skumanich A (1972) ApJ 171:565. Scholar
  88. Stelzer B, Micela G, Flaccomio E, Neuhäuser R, Jayawardhana R (2006) A&A 448(1):293. Scholar
  89. Stelzer B, Alcalá J, Biazzo K et al (2012) A&A 537:A94. Scholar
  90. Tinney CG, Reid IN (1998) Mon Not R Astron Soc 301:1031. Scholar
  91. Trigilio C, Leto P, Umana G, Leone F, Buemi CS (2004) A&A 418:593. Scholar
  92. West AA, Hawley SL, Bochanski JJ et al (2008) AJ 135:785. Scholar
  93. White SM, Kundu MR, Jackson PD (1989) A&A 225(1):112. Scholar
  94. Williams PKG, Berger E (2015) ApJ 808(2):189. Scholar
  95. Williams PKG, Cook BA, Berger E (2014) ApJ 785(1):9. Scholar
  96. Williams PKG, Berger E, Irwin J, Berta-Thompson ZK, Charbonneau D (2015a) ApJ 799(2):192. Scholar
  97. Williams PKG, Casewell SL, Stark CR et al (2015b) ApJ 815:64. Scholar
  98. Williams PKG, Gizis JE, Berger E (2017) ApJ 834(2):117. Scholar
  99. Wolszczan A, Route M, (2014) ApJ 788(1):23. Scholar
  100. Wong AS, Yung YL, Friedson AJ (2003) GeoRL 30(8):1447. Scholar
  101. Wright NJ, Drake JJ, Mamajek EE, Henry GW (2011) ApJ 743(1):48. Scholar
  102. Wu CS, Lee LC (1979) ApJ 230:621. Scholar
  103. Yantis WF, Sullivan WT III, Erickson WC (1977) BAAS 9:453. Scholar
  104. Yu S, Doyle JG, Kuznetsov A et al (2012) ApJ 752(1):60. Scholar
  105. Zarka P, Treumann RA, Ryabov BP, Ryabov VB (2001) Ap&SS 277:293. Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Harvard-Smithsonian Center for AstrophysicsCambridgeUSA

Personalised recommendations