HCN as a probe of the inner disk in a candidate proto-brown dwarf

Fuente: arXiv
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Autores principales: Riaz, B., Thi, W. -F., Machida, M. N.
Formato: Preprint
Publicado: 2024
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author Riaz, B.
Thi, W. -F.
Machida, M. N.
author_facet Riaz, B.
Thi, W. -F.
Machida, M. N.
contents The detection of Keplerian rotation is rare among Class 0 protostellar systems. We have investigated the high-density tracer HCN as a probe of the inner disk in a Class 0 proto-brown dwarf candidate. Our ALMA high angular resolution observations show the peak in the HCN (3-2) line emission arises from a compact component near the proto-brown dwarf with a small bar-like structure and a deconvolved size of $\sim$50 au. Radiative transfer modelling indicates that this HCN feature is tracing the innermost, dense regions in the proto-brown dwarf where a small Keplerian disk is expected to be present. The limited velocity resolution of the observations, however, makes it difficult to confirm the rotational kinematics of this feature. A brightening in the HCN emission towards the core center suggests that HCN can survive in the gas phase in the inner, dense regions of the proto-brown dwarf. In contrast, modelling of the HCO$^{+}$ (3-2) line emission indicates that it originates from the outer pseudo-disk/envelope region and is centrally depleted. HCN line emission can reveal the small-scale structures and can be an efficient observational tool to study the inner disk properties in such faint compact objects where spatially resolving the disk is nearly impossible.
format Preprint
id arxiv_https___arxiv_org_abs_2405_11321
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle HCN as a probe of the inner disk in a candidate proto-brown dwarf
Riaz, B.
Thi, W. -F.
Machida, M. N.
Solar and Stellar Astrophysics
Astrophysics of Galaxies
The detection of Keplerian rotation is rare among Class 0 protostellar systems. We have investigated the high-density tracer HCN as a probe of the inner disk in a Class 0 proto-brown dwarf candidate. Our ALMA high angular resolution observations show the peak in the HCN (3-2) line emission arises from a compact component near the proto-brown dwarf with a small bar-like structure and a deconvolved size of $\sim$50 au. Radiative transfer modelling indicates that this HCN feature is tracing the innermost, dense regions in the proto-brown dwarf where a small Keplerian disk is expected to be present. The limited velocity resolution of the observations, however, makes it difficult to confirm the rotational kinematics of this feature. A brightening in the HCN emission towards the core center suggests that HCN can survive in the gas phase in the inner, dense regions of the proto-brown dwarf. In contrast, modelling of the HCO$^{+}$ (3-2) line emission indicates that it originates from the outer pseudo-disk/envelope region and is centrally depleted. HCN line emission can reveal the small-scale structures and can be an efficient observational tool to study the inner disk properties in such faint compact objects where spatially resolving the disk is nearly impossible.
title HCN as a probe of the inner disk in a candidate proto-brown dwarf
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2405.11321