The 200-300 GHz Survey for 18 Class II Disks in the Ophiuchus Star-Forming Complex
Abstract
We measured the 198-310 GHz flux densities of 18 Class II protoplanetary disks in the Ophiuchus star-forming complex using the Submillimeter Array (SMA). The ∼200-300 GHz spectral indices (α200−300) of these disks are 2.3+0.2−0.5. In this observed frequency range, emission properties of the Ophiuchus disks are very similar to the 48 spatially compact Class II disks in the Taurus-Auriga region observed in a previous SMA survey. Combining the Ophiuchus and Taurus-Auriga samples, the Pearson correlation coefficient between α200−300 and the flux density at 250 GHz (F250 GHz) is 0.27 (p=0.02). We do not find a convincing correlation between α200−300 and the R95% radius of the disks. Our interpretation for the α200−300 values being close to 2 in the spatially compact disks is that at ≳ 200 GHz frequencies, the continuum emission in these disks is dominated by optically thick dust thermal emission, independent of F250 GHz and R95%. As a result, the (sub)millimeter luminosity and the apparent disk size are positively correlated, which has been found in numerous resolved emission surveys of Class II disks. In young clusters with ages of ∼1-2 Myr, Class II disks with smaller radii or lower (sub)millimeter luminosities are not necessarily those in which the dust mass budget has been consumed or dispersed.
Related
- The Magnetized Universe: From planet-forming disks to the high-redshift universe
- XUE. ProDiMo models of internally and externally irradiated planet-forming disks around 0.3-4.0 solar mass stars (The IRIS project I)
- Disk survey in the Serpens star-forming region: Environmental effects in nearby star-forming regions
- Survey of Orion Disks with ALMA (SODA) IV: Millimeter variability of protoplanetary disks
- The NIKA2 Cosmological Legacy Survey in COSMOS: Final 1.2,mm and 2,mm source catalogs and redshift distribution of dusty star-forming galaxies
BibTeX
@misc{chung2026200300,
title = {{The 200-300 GHz Survey for 18 Class II Disks in the Ophiuchus Star-Forming Complex}},
author = {Chia-Ying Chung and Hauyu Baobab Liu and Chuan-Yung Lin and Linjing Feng and Sean M. Andrews and Mark A. Gurwell and Melvyn Wright},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.02619},
eprint = {2610.02619},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.02619},
}
RIS
TY - UNPB
TI - The 200-300 GHz Survey for 18 Class II Disks in the Ophiuchus Star-Forming Complex
AU - Chia-Ying Chung
AU - Hauyu Baobab Liu
AU - Chuan-Yung Lin
AU - Linjing Feng
AU - Sean M. Andrews
AU - Mark A. Gurwell
AU - Melvyn Wright
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.02619
UR - https://arxiv.org/abs/2610.02619
AB - We measured the 198-310 GHz flux densities of 18 Class II protoplanetary disks in the Ophiuchus star-forming complex using the Submillimeter Array (SMA). The ∼200-300 GHz spectral indices (α_200−300) of these disks are 2.3^+0.2_−0.5. In this observed frequency range, emission properties of the Ophiuchus disks are very similar to the 48 spatially compact Class II disks in the Taurus-Auriga region observed in a previous SMA survey. Combining the Ophiuchus and Taurus-Auriga samples, the Pearson correlation coefficient between α_200−300 and the flux density at 250 GHz (F_250 GHz) is 0.27 (p=0.02). We do not find a convincing correlation between α_200−300 and the R_95% radius of the disks. Our interpretation for the α_200−300 values being close to 2 in the spatially compact disks is that at ≳ 200 GHz frequencies, the continuum emission in these disks is dominated by optically thick dust thermal emission, independent of F_250 GHz and R_95%. As a result, the (sub)millimeter luminosity and the apparent disk size are positively correlated, which has been found in numerous resolved emission surveys of Class II disks. In young clusters with ages of ∼1-2 Myr, Class II disks with smaller radii or lower (sub)millimeter luminosities are not necessarily those in which the dust mass budget has been consumed or dispersed.
ER -