New observations of the horsehead nebula reveal Its magnetic fields

The James Clerk Maxwell Telescope (JCMT), situated near the summit of Maunakea in Hawaii, is the largest telescope worldwide designed exclusively for submillimeter-wavelength observations. The JCMT operates under the East Asia Observatory (EAO) and played a pivotal role in a remarkable scientific endeavor. Mallory Go, a former student of Molokai’i High School and now a graduate student at Brown University, secured valuable observation time with the JCMT through the Maunakea Scholars program in 2018. Assisted by EAO astronomer Dr. Harriet Parsons, Go utilized the JCMT’s POL-2 instrument to capture unique polarized images of the Horsehead Nebula. These images unveiled the nebula’s magnetic fields.

Go subsequently presented her findings at a Science Fair on behalf of Molokai’i High School. A year later, a team of astronomers from the Korea Astronomy and Space Science Institute (KASI), the University of Science and Technology (UST), and University College London (UCL) harnessed Go’s observations to conduct a quantitative analysis of the magnetic fields’ strength and role within the region. The research paper titled “Magnetic Fields in the Horsehead Nebula” was recently published in The Astronomical Journal.

During the 2018 observations, Go employed the JCMT’s POL-2 instrument, which combines with the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) instrument to gather polarization data. These instruments allow astronomers to study the impact of magnetic fields on the alignment of interstellar dust particles.

Dr. Parsons explained the role of the POL-2 instrument in an EAO press release, likening it to a pair of polarized sunglasses positioned in front of the telescope. By analyzing the brightness of the observed light and determining if it is influenced by magnetic fields, astronomers can examine gas and dust clouds in various regions, both within our galaxy and beyond, thereby expanding our understanding of their structure.

The team of astronomers from KASI, UST, and UCL supplemented Go’s observations with additional data obtained using the JCMT’s other operational instruments—the Heterodyne Array Receiver Program (HARP) and the Auto Correlation Spectral Imaging System (ACSIS). These instruments enabled measurements of the region’s brightness and density. The HARP instrument provided spectral line data, revealing the presence of a variant of carbon monoxide called oxygen-18 (C18O), which is a stable isotope of oxygen believed to originate in molecular clouds.

Dr. Kate Pattle, an astronomer from UCL and one of the co-authors of the study, expressed her enthusiasm for the data and the insights it provides. She praised Mallory Go for granting them the opportunity to study such a magnificent and renowned region of the sky. The team’s findings shed light on the factors that shape the Horsehead Nebula. The observations unveil two dense regions concealed within the nebula, one representing the head and mane of the horse, which interacts with the ultraviolet photons emitted by nearby young and bright stars.

The JCMT’s array of instruments provided the team with a unique perspective on the interaction between the “head” and “mane” of the Horsehead Nebula and the nearby young stars. This interaction appeared to have a significant impact on the nebula’s magnetic field. The team proposed a theory suggesting that as the Horsehead Nebula formed, the magnetic field lines folded back on themselves along the line of sight from the observatory. Behind this ridge, they observed a cold and dense clump of material that seemed to have been shielded from these interactions. The team speculates that this clump has the potential to develop into a new star system.

The significance of these observations lies in the fact that they provide astronomers with a first-time glimpse into the behavior of magnetic field lines in regions such as the Horsehead Nebula. Dr. Pattle emphasized the excitement surrounding this discovery, stating that it offers crucial insights into the ongoing process of star formation, even in environments where the cold gas required for new star formation is being eroded by the radiation from neighboring hot and young stars. The team’s findings are particularly valuable as they contribute to our understanding of the formation of our own solar system, which is believed to have originated within a cluster of stars. By studying star formation in the Horsehead Nebula, astronomers hope to gain insights into the history of our own solar system.

Mallory Go, reflecting on her participation in the Maunakea Scholars program, expressed her enthusiasm for the opportunity to utilize the telescopes on Maunakea. She chose to study the Horsehead Nebula due to its captivating beauty and the limited research available on the subject. Go’s observations marked the first attempt at visualizing the nebula’s magnetic field, adding a new dimension to the understanding of this iconic astronomical object.

Source: Universe Today

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