New Light on Young Stars:
Spitzer's View of Circumstellar Disks

The Discovery of a Photoevaporated Circumbinary Disk in the Orion Nebula

First Author:
Ricci Luca
Email: lricci AT eso.org
ESO
Daxenaeckerweg 20
Garching bei Munchen, 85748, Germany
Coauthors:
Robberto, Massimo, STScI
Da Rio, Nicola, MPIA
Soderblom, David, STScI

Abstract
We have found a photoevaporated disk in the Orion Nebula that includes a wide binary. HST/ACS observations of the proplyd 124-132 show two point-like sources separated by 0.15 arcsec, or about 60 AU at the distance of Orion. The two sources have nearly identical I and z magnitudes. We analyze the brightest component, source N, comparing the observed magnitudes with those predicted using a 1 Myr Baraffe/NEXTGEN isochrone with different amounts of accretion luminosity and extinction. We find that a low mass (~0.04 M_sun) brown dwarf ~1 Myr old with mass accretion rate ~10^-10.3 M_sun/yr, typical for objects of this mass, and about 2 magnitudes of visual extinction provides the best explanation to the data. This is the first observation of a circumbinary disk undergoing photoevaporation and, if confirmed by spectroscopic observations, the first direct detection of a wide substellar pair still accreting and enshrouded in its circumbinary disk.

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