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 θ ¹ Ori C at the center of the Orion Nebula Cluster (ONC). The object was known to have extended emission pointing away from θ 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 (∼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 θ ¹ Ori C as a second generation of star formation, which can explain both its young age and the presence of its disk.