Grain Growth and Density Distribution of the Youngest Protostellar Systems

TL;DR

This study measures dust properties in the youngest protostars, revealing significant grain growth and radial dependence of dust characteristics, which enhances understanding of early star formation processes.

Contribution

It provides new measurements of dust opacity spectral indexes in Class 0 protostars using advanced interferometry, showing evidence of early grain growth and dust segregation.

Findings

Dust grains have already grown significantly in Class 0 sources.

Beta values are around or less than 1, indicating grain growth.

Radial dependence of beta suggests faster growth in denser central regions.

Abstract

We present dust opacity spectral indexes (beta) of the youngest protostellar systems (so-called Class 0 sources), L1448 IRS 2, L1448 IRS 3, and L1157, obtained between 1.3 mm and 2.7 mm continua, using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). The unprecedented compact configuration and image fidelity of CARMA allow a better detection of the dust continuum emission from Class 0 sources, with a less serious missing flux problem normally associated with interferometry. Through visibility-modeling at both 1.3 mm and 2.7 mm simultaneously, as well as image- and visibility-comparison, we show that beta of the three Class 0 sources are around or smaller than 1, indicating that dust grains have already significantly grown at the Class 0 stage. In addition, we find a radial dependence of beta, which implies faster grain growth in the denser central regions and/or dust segregation. Density distributions of the Class 0 sources are also addressed by visibility-modeling.