ALMA 1.3 Millimeter Map of the HD 95086 System

TL;DR

This paper presents high-resolution ALMA 1.3 mm observations of the HD 95086 system, revealing the structure of its debris disk, the location of its Kuiper-belt analog, and a background galaxy, providing insights into planetary system formation.

Contribution

First resolved the Kuiper-belt analog in HD 95086, characterizing its broad, inclined disk and sharp boundaries, and identified a background galaxy near the disk edge.

Findings

The debris disk extends from 106 to 320 au with a power-law surface density.

The Kuiper-belt analog is a broad, inclined ring at about 200 au.

A bright source near the disk edge is likely a high-redshift galaxy.

Abstract

Planets and minor bodies such as asteroids, Kuiper-belt objects and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid- and Kuiper-belt analogs. The location of the Kuiper-belt analog is resolved for the first time. The system can be depicted as a broad ($\Delta R/R \sim$0.84), inclined (30\arcdeg$\pm$3\arcdeg) ring with millimeter emission peaked at 200$\pm$6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106$\pm$6 to 320$\pm$20 au with a surface density distribution described by a power law with an index of --0.5$\pm$0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming co-planarity with the observed disk.