- Casewell, SL;
- Lawrie, KA;
- Maxted, PFL;
- Marley, MS;
- Fortney, JJ;
- Rimmer, PB;
- Littlefair, SP;
- Wynn, G;
- Burleigh, MR;
- Helling, Ch
WD0137-349 is a white dwarf-brown dwarf binary system in a 116 minute orbit.
We present radial velocity observations and multiwaveband photometry from V, R
and I in the optical, to J, H and Ks in the near-IR and [3.6], [4.5], [5.8] and
[8.0] microns in the mid-IR. The photometry and lightcurves show variability in
all wavebands, with the amplitude peaking at [4.5] microns, where the system is
also brightest. Fluxes and brightness temperatures were computed for the heated
and unheated atmosphere of the brown dwarf (WD0137-349B) using synthetic
spectra of the white dwarf using model atmosphere simulations. We show that the
flux from the brown dwarf dayside is brighter than expected in the Ks and [4.5]
micron bands when compared to models of irradiated brown dwarfs with full
energy circulation and suggest this over-luminosity may be attributed to H2
fluorescence or H3+ being generated in the atmosphere by the UV irradiation.