A CANDIDATE PLANETARY-MASS OBJECT WITH A PHOTOEVAPORATING DISK IN ORION

Abstract

In this work, we report the discovery of a candidate planetary-mass object with a photoevaporating protoplanetary disk, Proplyd. 133-353, which is near the massive star theta(1) Ori C at the center of the Orion Nebula Cluster (ONC). The object was known to have extended emission pointing away from theta(1) Ori. C, indicating ongoing external photoevaporation. Our near-infrared spectroscopic data and the location on the H-R diagram suggest that the central source of Proplyd. 133-353 is substellar (similar to M9.5) and has a mass probably less than 13 Jupiter mass and an age younger than 0.5 Myr. Proplyd. 133-353 shows a similar ratio of X-ray luminosity to stellar luminosity to other young stars in the ONC with a similar stellar luminosity and has a similar proper motion to the mean one of confirmed ONC members. We propose that Proplyd. 133-353 formed in a very low-mass dusty cloud or an evaporating gas globule near theta(1) Ori C as a second generation of star formation, which can explain both its young age and the presence of its disk.