2 New Planetary Mass Binaries

Two Extraordinary Substellar Binaries at the T/Y Transition and the Y-Band Fluxes of the Coolest Brown Dwarfs

Quote :

Using Keck laser guide star adaptive optics imaging, we have found that the T9 dwarf WISE J1217+1626 and T8 dwarf WISE J1711+3500 are exceptional binaries, with unusually wide separations (~0.8 arcsec, 8-15 AU), large near-IR flux ratios (~2-3 mags), and small mass ratios (~0.5). Keck/NIRSPEC H-band spectra give a spectral type of Y0 for WISE J1217+1626B, and photometric estimates suggest T9.5 for WISE J1711+3500B. The WISE J1217+1626AB system is very similar to the T9+Y0 binary CFBDSIR J1458+1013AB; these two systems are the coldest known substellar multiples, having secondary components of ~400 K and being planetary-mass binaries if their ages are <~1 Gyr. Both WISE J1217+1626B and CFBDSIR J1458+1013B have strikingly blue Y-J colors compared to previously known T dwarfs, including their T9 primaries. Combining all available data, we find that Y-J color drops precipitously between the very latest T dwarfs and the Y dwarfs. The fact that this is seen in (coeval, mono-metallicity) binaries demonstrates that the color drop arises from a change in temperature, not surface gravity or metallicity variations among the field population. Thus, the T/Y transition established by near-IR spectra coincides with a significant change in the ~1 micron fluxes of ultracool photospheres. One explanation is the depletion of potassium, whose broad absorption wings dominate the far-red optical spectra of T dwarfs. This large color change suggests that far-red data may be valuable for classifying objects of <~500 K.

WISE J1217+1626 B = 5.5-13 M_Jupiter a = 8 AUs

WISE J1711+3500 B = 8.1-20 M_Jupiter a = 15 AUs

Quite within planetary regime.

On a similar theme, 2MASSJ035523.51+113337.4: A Young, Dusty, Nearby, Isolated Brown Dwarf Resembling A Giant Exoplanet

The spectral type is given as L5γ, where the γ denotes very low surface gravity. In this scheme β represents intermediate gravity and ɑ represents normal gravity of field objects.

An old discovery but unnoticed. Browsing previous threads I haven't found it. In case of double post, please merge it.

I don't get why EPE hasn't listed these ones which seem having all the qualifications to be regarded as planets.

Two Extraordinary Substellar Binaries at the T/Y Transition and the Y-band Fluxes of the Coolest Brown Dwarfs

Quote :

Using Keck laser guide star adaptive optics imaging, we have found that the T9 dwarf WISE J1217+1626 and T8 dwarf WISE J1711+3500 are exceptional binaries, with unusually wide separations (~0.8 arcsec, 8-15 AU), large near-IR flux ratios (~2-3 mags), and small mass ratios (~0.5) compared to previously known field ultracool binaries. Keck/NIRSPEC H-band spectra give a spectral type of Y0 for WISE J1217+1626B, and photometric estimates suggest T9.5 for WISE J1711+3500B. The WISE J1217+1626AB system is very similar to the T9+Y0 binary CFBDSIR J1458+1013AB; these two systems are the coldest known substellar multiples, having secondary components of ~400 K and being planetary-mass binaries if their ages are <~1 Gyr. Both WISE J1217+1626B and CFBDSIR J1458+1013B have strikingly blue Y-J colors compared to previously known T dwarfs, including their T9 primaries. Combining all available data, we find that Y-J color drops precipitously between the very latest T dwarfs and the Y dwarfs. The fact that this is seen in (coeval, mono-metallicity) binaries demonstrates that the color drop arises from a change in temperature, not surface gravity or metallicity variations among the field population. Thus, the T/Y transition established by near-IR spectra coincides with a significant change in the ~1 micron fluxes of ultracool photospheres. One explanation is the depletion of potassium, whose broad absorption wings dominate the far-red optical spectra of T dwarfs. This large color change suggests that far-red data may be valuable for classifying objects of <~500 K.

For for WISE J1217+1626 system:

M₁=11.5-35 M_Jup, m₂= 5.5-20 M_Jup a= 8 AUs

For WISE J1711+3500:

M₁= 19-48 M_Jup, m₂= 8.7-26 M_Jup a= 15 AUs



Published 10/2012: http://adsabs.harvard.edu/abs/2012ApJ...758...57L

Previous thread

...started by Edasich

I wish I could type a *doh* emoticon.

Anyway the detection is now official.

Haha unnoticed eh?
Merged.

Sirius_Alpha wrote:

Haha unnoticed eh?
Merged.

Unnoticed by EPE for sure.