# The Ophiuchus DIsk Survey Employing ALMA (ODISEA): Disk Dust Mass Distributions across Protostellar Evolutionary Classes

## TL;DR

This study uses ALMA observations to measure and analyze the dust mass distribution in 279 protostellar disks in the Ophiuchus region, revealing a trend of decreasing mass with evolution but also significant overlap and environmental influences.

## Contribution

First comprehensive ALMA-based survey of disk dust masses across protostellar classes in Ophiuchus, highlighting the complex evolution and environmental effects on disk mass.

## Key findings

- Disk masses follow a log-normal distribution with decreasing mean from Class I to II.
- High dispersion causes significant overlap between classes.
- Environmental factors may influence initial disk mass and dust regeneration.

## Abstract

As protostars evolve from optically faint / infrared bright (Class I) sources to optically bright / infrared faint (Class II) the solid material in their surrounding disks accumulates into planetesimals and protoplanets. The nearby, young Ophiuchus star-forming region contains hundreds of protostars in a range of evolutionary states. Using the Atacama Large Millimeter Array to observe their millimeter continuum emission, we have measured masses of, or placed strong upper limits on, the dust content of 279 disks. The masses follow a log-normal distribution with a clear trend of decreasing mass from less to more evolved protostellar infrared class. The (logarithmic) mean Class I disk mass, M = 3.8 M_Earth, is about 5 times greater than the mean Class II disk mass, but the dispersion in each class is so high, sigma(logM) ~ 0.8-1, that there is a large overlap between the two distributions. The disk mass distribution of flat-spectrum protostars lies in between Classes I and II. In addition, three Class III sources with little to no infrared excess are detected with low disk masses, M ~ 0.3 M_Earth. Despite the clear trend of decreasing disk mass with protostellar evolutionary state in this region, a comparison with surveys of Class II disks in other regions shows that masses do not decrease monotonically with age. This suggests that the cloud-scale environment may determine the initial disk mass scale or that there is substantial dust regeneration after 1 Myr.