Spatially Resolved 3 micron Spectroscopy of Elias 1: Origin of Diamonds in Protoplanetary Disks

TL;DR

This study uses spatially resolved 3 micron spectroscopy to investigate the distribution of PAH and diamond emissions in the protoplanetary disk of Elias 1, revealing insights into the origin of diamonds in such environments.

Contribution

It provides the first spatially resolved observations of diamond emission in a protoplanetary disk, suggesting a link between energetic particle irradiation and diamond formation.

Findings

PAH emission is absent in the inner disk and extends outward to 100 AU.

Diamond emission is centrally concentrated around 30 AU.

Elias 1 is one of only three known Herbig Ae/Be stars with diamond emission.

Abstract

We present spatially resolved 3 um spectra of Elias 1 obtained with an adaptive optics system. The central part of the disk is almost devoid of PAH emission at 3.3 um; it shows up only at 30 AU and beyond. The PAH emission extends up to 100 AU, at least to the outer boundary of our observation. The diamond emission, in contrast, is more centrally concentrated, with the column density peaked around 30 AU from the star. There are only three Herbig Ae/Be stars known to date that show diamond emission at 3.53 um. Two of them have low-mass companions likely responsible for the large X-ray flares observed toward the Herbig Ae/Be stars. We speculate on the origin of diamonds in circumstellar disks in terms of the graphitic material being transformed into diamond under the irradiation of highly energetic particles.