Observers study the complex magnetic field of the Lindts 43 molecular cloud

Using the James Clark Maxwell Telescope (JCMD), an international team of astronomers has observed a molecular cloud named Lindz 43. The results of the observations were published on May 18. arXiv A pre-print server, provide additional cues to this cloud’s complex magnetic field.

Linds 43, or L43 for short, is a dense and complex molecular cloud about 400 light-years away in the northern part of the Obichus star-forming region. The cloud contains a bright starless core embedded in a long diffuse filament, a T-Tauri star (embedded RNO 90) and a young class I protostar (RNO 91). Previous studies of L43 have found that it has a large magnetic field parallel to the filament, although it is tilted slightly to the south.

A team of astronomers led by Janic Karolyi of the University of Central Lancashire, UK, has made polarization observations of dust emission from L43 as part of the larger B-field in Star Forming Regions Observations (BISTRO) project. For this purpose, they used JCMT’s Submillimeter Common-User Bolometer Array 2 (SCUBA2)/POL-2.

„We provided polarization measurements of the infrared dark molecular cloud L43 at 850 µm using JCMT/POL-2 as part of the JCMT BISTRO survey,” the researchers wrote in the paper.

Observations of L43 show that molecular hydrogen (H₂) with a column density typical of dense nonstellar cores, and a power law index of −0.85. Therefore, the results suggest a possible reduction, but not a complete loss, in grain alignment efficiency deep within the molecular cloud.

Furthermore, the study identified L43’s complex and multi-component magnetic field, which is divided into three regions. One region is slightly offset from the dense submillimetre-bright center (region 2), another region is more diffuse to the east (region 1), and the remaining region coincides spatially in the plane of the sky with carbon monoxide emission. By RNO 91.

The observations found an alignment between the magnetic field and the outflow cavity walls, which was different from the magnetic field in the rest of the cloud. Based on the collected data, the magnetic field strengths in Zone 1 and Zone 2 were calculated to be 40–90 μG and 70–160 μG, respectively. The magnetic field strength at the exit region is estimated to be between 120 and 260 μG.

The paper’s authors added that there appears to be an evolutionary gradient in which L43 is embedded in the isolated strand. The gradient starts with the highly evolved source RNO 90, closest to the Scorpius–Centaurus stellar association (Sco OB2) and moves from this association towards RNO 91, and then eventually towards the starless core.