Subhanjoy MOHANTY : Harvard-Smithsonian Center for Astrophysics
An Edge-On Disk around the Planetary-Mass Companion
I present new VLT NIR photometry and low-resolution spectroscopy of 2M1207b, the recently discovered planetary-mass companion to a young brown dwarf in TW HyA. Comparison to the latest synthetic spectra and evolutionary model colors reveals excellent agreement with a mass of 6--10 Jupiters and Teff =1600 +/- 100K, for the expected age of ~10 Myrs and d = 50--70 pc. However, the object is 2.5 mags fainter than expected in all NIR photometric bands and in bolometric luminosity, strongly indicating gray extinction due to an edge-on disk. This is consistent with the known presence of a relatively evolved, high-inclination disk around the primary, as well as with similar gray extinction seen in other edge-on sources (e.g., KH15D). Thus the 2M1207 system presents not only the first evidence of a planetary-mass companion to a brown dwarf, but also of the presence of a disk around the planetary companion. Finally, our mass determination implies a mass ratio of ~0.3, suggesting a binary-like, instead of planet-like, formation scenario for the companion (results presented in detail in Mohanty et al. 2006, submitted).Last modified: Sun Jul 9 18:00:05 2006