Protoplanetary Disk Masses in the Young NGC 2024 Cluster

TL;DR

This study surveys protoplanetary disks in NGC 2024, measuring their masses via submillimeter observations, revealing a distribution with some more massive disks compared to other clusters, and no clear influence from nearby massive stars.

Contribution

First detailed submillimeter survey of disks in NGC 2024, providing disk mass measurements and analyzing environmental effects on disk properties.

Findings

Detected 22 disks with flux densities 5-330 mJy

Disk masses range from 0.003 to 0.2 solar masses

No evidence of disk mass dependence on proximity to massive star

Abstract

We present the results from a Submillimeter Array survey of the 887 micron continuum emission from the protoplanetary disks around 95 young stars in the young cluster NGC 2024. Emission was detected from 22 infrared sources, with flux densities from ~5 to 330 mJy; upper limits (at 3sigma) for the other 73 sources range from 3 to 24 mJy. For standard assumptions, the corresponding disk masses range from ~0.003 to 0.2Msolar, with upper limits at 0.002--0.01Msolar. The NGC 2024 sample has a slightly more populated tail at the high end of its disk mass distribution compared to other clusters, but without more information on the nature of the sample hosts it remains unclear if this difference is statistically significant or a superficial selection effect. Unlike in the Orion Trapezium, there is no evidence for a disk mass dependence on the (projected) separation from the massive star IRS2b in the NGC 2024 cluster. We suggest that this is due to either the cluster youth or a comparatively weaker photoionizing radiation field.