Two confirmed class I very low-mass objects in Taurus

TL;DR

This study confirms two very low-mass objects in Taurus as class I proto-brown dwarfs, providing evidence that brown dwarfs form through similar stages as low-mass stars.

Contribution

The paper provides the first direct evidence that [GKH94] 41 and IRAS 04191+1523B are class I objects, confirming their status as proto-brown dwarfs and supporting common formation scenarios.

Findings

Both objects are surrounded by envelopes, confirming their class I status.

Estimated final masses suggest they will become brown dwarfs or very low-mass stars.

The binary IRAS 04191+1523B was spatially resolved in the continuum map.

Abstract

[GKH94] 41 and IRAS 04191+1523B were previously identified to be proto-brown dwarf candidates in Taurus. [GKH94] 41 was classified to be a class I object. The dereddened spectral energy distribution of the source was later found to be suggestive of a class II object. IRAS 04191+1523B is a class I object that is the secondary component of a binary. We determine the evolutionary stage of [GKH94] 41 and estimate the final masses of the two proto-brown dwarf candidates. We used archive millimeter observations to produce continuum maps and collected data from the literature to construct the spectral energy distribution of the targets. Our continuum maps revealed that both [GKH94] 41 and IRAS 04191+1523B are surrounded by envelopes. This provides direct evidence that [GKH94] 41 is a class I object, not class II, as previously classified. For IRAS 04191+1523B, our continuum map spatially resolved the binary. Our estimated final masses are below 49$^{+56}_{-27}$ $M_{\rm J}$ and 75$^{+40}_{-26}$ $M_{\rm J}$ for [GKH94] 41 and IRAS 04191+1523B, respectively. This indicates that both sources will likely become brown dwarfs or very low-mass stars. Therefore, [GKH94] 41 and IRAS 04191+1523B are two new confirmed class I very low-mass objects. Their existence also supports the scenario that brown dwarfs have the same formation stages as low-mass stars.