WISE J104915.57-531906.1 is the nearest brown dwarf binary to our Solar system , consisting of two brown dwarfs in the L/T transition : Luhman 16A & B .
In this paper we present the first map of Luhman 16A , and maps of Luhman 16B for two epochs .
Our maps were created by applying Aeolus , a Markov–Chain Monte Carlo code that maps the top–of–the–atmosphere ( TOA ) structure of brown dwarf and other ultracool atmospheres , to light curves of Luhman 16A & B using the Hubble Space Telescope ’ s G141 and G102 grisms . Aeolus retrieved three or four spots in the top–of–the–atmosphere of Luhman 16A & B , with a surface coverage of 19 % –32 % ( depending on an assumed rotational period of 5 hr or 8 hr ) or 21 % –38.5 % ( depending on the observational epoch ) respectively .
The brightness temperature of the spots of the best–fit models was \sim 200 K hotter than the background TOA .
We compared our Luhman 16B map with the only previously published map .
Interestingly , our map contained a large , cooler ( \Delta T \sim 51 K ) than the background TOA spot that lay at low latitudes , in agreement with the previous Luhman 16B map .
Finally , we report the detection of a feature reappearing in Luhman 16B light curves that are separated by tens of hundreds of rotations from each other .
We speculate this feature is related to TOA structures of Luhman 16B .