HD 106906 b: A planetary-mass companion outside a massive debris disk

Vanessa Bailey, Tiffany Meshkat, Megan Reiter, Katie Morzinski, Jared Males, Kate Y L Su, Philip M Hinz, Matthew Kenworthy, Daniel P Stark, Eric Mamajek, Runa Briguglio, Laird M Close, Katherine B. Follette, Alfio Puglisi, Timothy Rodigas, Alycia J. Weinberger, Marco Xompero

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99 Scopus citations


We report the discovery of a planetary-mass companion, HD 106906 b, with the new Magellan Adaptive Optics (MagAO) + Clio2 system. The companion is detected with Clio2 in three bands: J, KS , and L′, and lies at a projected separation of 7.″1 (650 AU). It is confirmed to be comoving with its 13 ± 2 Myr F5 host using Hubble Space Telescope Advanced Camera for Surveys astrometry over a time baseline of 8.3 yr. DUSTY and COND evolutionary models predict that the companion's luminosity corresponds to a mass of 11 ± 2 M Jup, making it one of the most widely separated planetary-mass companions known. We classify its Magellan/Folded-Port InfraRed Echellette J/H/K spectrum as L2.5 ± 1; the triangular H-band morphology suggests an intermediate surface gravity. HD 106906 A, a pre-main-sequence Lower Centaurus Crux member, was initially targeted because it hosts a massive debris disk detected via infrared excess emission in unresolved Spitzer imaging and spectroscopy. The disk emission is best fit by a single component at 95 K, corresponding to an inner edge of 15-20 AU and an outer edge of up to 120 AU. If the companion is on an eccentric (e > 0.65) orbit, it could be interacting with the outer edge of the disk. Close-in, planet-like formation followed by scattering to the current location would likely disrupt the disk and is disfavored. Furthermore, we find no additional companions, though we could detect similar-mass objects at projected separations >35 AU. In situ formation in a binary-star-like process is more probable, although the companion-to-primary mass ratio, at <1%, is unusually small.

Original languageEnglish (US)
Article numberL4
JournalAstrophysical Journal Letters
Issue number1
Publication statusPublished - Jan 1 2014



  • instrumentation: adaptive optics
  • open clusters and associations: individual (Lower Centaurus Crux)
  • planet-disk interactions
  • planetary systems
  • stars: individual (HD 106906)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Bailey, V., Meshkat, T., Reiter, M., Morzinski, K., Males, J., Su, K. Y. L., ... Xompero, M. (2014). HD 106906 b: A planetary-mass companion outside a massive debris disk. Astrophysical Journal Letters, 780(1), [L4]. https://doi.org/10.1088/2041-8205/780/1/L4