Finding Substructures in Protostellar Disks in Ophiuchus

The Astronomical Journal, vol. 166, pp. 184

Abstract

Abstract High-resolution, millimeter observations of disks at the protoplanetary stage reveal substructures such as gaps, rings, arcs, spirals, and cavities. While many protoplanetary disks host such substructures, only a few at the younger protostellar stage have shown similar features. We present a detailed search for early disk substructures in Atacama Large Millimeter/submillimeter Array 1.3 and 0.87 mm observations of ten protostellar disks in the Ophiuchus star-forming region. Of this sample, four disks have identified substructure, two appear to be smooth disks, and four are considered ambiguous. The structured disks have wide Gaussian-like rings (σ R /R disk ∼ 0.26) with low contrasts (C < 0.2) above a smooth disk profile, in comparison to protoplanetary disks where rings tend to be narrow and have a wide variety of contrasts (σ R /R disk ∼ 0.08 and C ranges from 0 to 1). The four protostellar disks with the identified substructures are among the brightest sources in the Ophiuchus sample, in agreement with trends observed for protoplanetary disks. These observations indicate that substructures in protostellar disks may be common in brighter disks. The presence of substructures at the earliest stages suggests an early start for dust grain growth and, subsequently, planet formation. The evolution of these protostellar substructures is hypothesized in two potential pathways: (1) the rings are the sites of early planet formation, and the later observed protoplanetary disk ring–gap pairs are secondary features, or (2) the rings evolve over the disk lifetime to become those observed at the protoplanetary disk stage.

Authors 8

1. Arnaud Michel corresponding

   Queen's University

   Affiliation as printed

   Department of Physics, Engineering Physics and Astronomy, Queens University, Kingston, ON, K7L 3N6, Canada; arnaud.michel@queensu.ca

   Department of Physics, Engineering Physics and Astronomy, Queens University, Kingston, ON, K7L 3N6, Canada

2. Sarah Sadavoy

   Queen's University

   Affiliation as printed

   Department of Physics, Engineering Physics and Astronomy, Queens University, Kingston, ON, K7L 3N6, Canada; arnaud.michel@queensu.ca

   Department of Physics, Engineering Physics and Astronomy, Queens University, Kingston, ON, K7L 3N6, Canada

3. Patrick Sheehan corresponding

   National Radio Astronomy Observatory

   Affiliation as printed

   National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA

4. Leslie W. Looney

   University of Illinois Urbana-Champaign

   Affiliation as printed

   Department of Astronomy, University of Illinois, Urbana, IL 61801, USA

5. Erin G. Cox

   Northwestern University

   Affiliation as printed

   Center for Interdisciplinary Exploration and Research in Astronomy, Northwestern University, 1800 Sherman Road, Evanston, IL 60202, USA

6. John J. Tobin

   National Radio Astronomy Observatory

   Affiliation as printed

   National Radio Astronomy Observatory, Charlottesville, VA, USA

7. Nienke van der Marel Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, P.O. Box 9513, 2333 CA, Leiden, The Netherlands

8. Dominique M. Segura-Cox

   The University of Texas at Austin

   Affiliation as printed

   Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Austin, TX 78712, USA