Revised SED of the triple protostellar system VLA 1623-2417

TL;DR

This study uses new ALMA Band 9 data to revise the spectral energy distribution of the triple protostellar system VLA 1623-2417, revealing that the secondary component B is more similar to A at shorter wavelengths than previously thought.

Contribution

The paper provides a revised analysis of the SED of VLA 1623-2417 using high-frequency ALMA data, challenging previous assumptions about the flux contributions of its components.

Findings

VLA 1623-2417 B's SED peaks at shorter wavelengths than previously thought.

Component B likely contributes significantly to flux at wavelengths below 450 μm.

The nature of VLA 1623-2417 B remains puzzling due to lack of circumstellar gas emission.

Abstract

VLA 1623$-$2417 is a triple protostellar system deeply embedded in Ophiuchus A. Sources A and B have a separation of 1.1", making their study difficult beyond the submillimeter regime. Lack of circumstellar gas emission suggested that VLA 1623$-$2417 B has a very cold envelope and is much younger than source A, generally considered the prototypical Class 0 source. We explore the consequences of new ALMA Band 9 data on the spectral energy distribution (SED) of VLA 1623$-$2417 and their inferred nature. Using dust continuum observations spanning from centimeter to near-infrared wavelengths, the SED of each component in VLA 1623$-$2417 is constructed and analysed. The ALMA Band 9 data presented here show that the SED of VLA 1623$-$2417 B does not peak at 850 $\mu$m as previously expected, but instead presents the same shape as VLA 1623$-$2417 A at wavelengths shorter than 450 $\mu$m. The results presented here indicate that the previous assumption that the flux in $Herschel$ and Spitzer observations is solely dominated by VLA 1623$-$2417 A is not valid, and instead, VLA 1623$-$2417 B most likely contributes a significant fraction of the flux at $\lambda~<$ 450 $\mu$m. These results, however, do not explain the lack of circumstellar gas emission and puzzling nature of VLA 1623$-$2417 B.