Author: jcmtops

Molokai student Mallory Go has co-authored a paper published in The Astronomical Journal under the title “Magnetic Fields in the Horsehead Nebula using data from the James Clerk Maxwell Telescope. Go (who graduated in 2021) was awarded time under the Maunakea Scholars program – a program that gives students at High Schools in Hawaii access to the telescopes on Maunakea.

Using the James Clerk Maxwell Telescope (JCMT) in 2018 Go obtained unique images of the Horsehead Nebula in polarized light – a technique astronomers use to reveal the magnetic field within the Nebula. Despite the Horsehead Nebula being such an iconic cloud, which is famous amongst astronomers, Go was the first to propose such observations.

“When I heard about the Maunakea Scholars program I was excited. It seemed to me to be such a fantastic opportunity to use the Telescopes on Maunakea” said Go reflecting on her experience “I chose to study the Hosrehead nebula because I thought it was beautiful and I didn’t find much research on it.” Once the proposed observations were taken, and working with astronomer Dr Parsons, Go presented her work as part of her Science Fair representing Molokai`i High School. After this, the data were shared with top astronomers in the field who perused the work further. Jihye Hwang, Kate Pattle and Jongsoo Kim built on Go’s observations to perform a quantitative analysis of the strength and role of magnetic fields in the region.

Magnetic field detections overlaid on a two-color composite of Hubble Space Telescope image taken at two near-IR wavelengths (Mikulski Archive for Space Telescopes). Black and orange segments show magnetic field orientations inferred from JCMT and Palomar Observatory. Credit: Hwang et al. 2023.

“The data are impressive and what they tell us is even more impressive,” said co-author Dr Kate Pattle, from University College London (UCL), UK. “I am delighted that Mallory has given us the chance to work on such a beautiful and iconic region of the sky – and what we’ve found helps us to understand why the Horsehead Nebula has the shape that it does. These observations tell us a story of two dense regions hidden in the Horsehead. We see a ridge of warm gas and dust – the head and mane of the horse – that is interacting with the ultraviolet photons from nearby bright young stars. But sheltered behind that ridge, we see a cold clump of dense material which we think will go on to form a new solar system like our own. What’s so new and exciting about these observations is that we get to see for the first time what the magnetic field within these regions is doing.”

The observations obtained by Go in 2018 were taken by one of the JCMT’s most cutting-edge instruments: POL-2. POL-2 is a polarimeter which is able to take measurements of the alignment of interstellar dust that can be influenced by magnetic fields in space. “You can think of POL-2 as a pair of polarized sunglasses sitting in front of the telescope,” said Head of Operations Dr Harriet Parsons. “In Hawaii many of us are used to wearing polarized sunglasses – they help us to see better by cutting down glare – but at the telescope by rotating the polarized lenses we analyze the brightness of the light being observed and deduce if it is under the effect of magnetic fields. Astronomers can look at clouds of gas and dust using such instruments – regions both within our own galaxy or beyond – and expand their understanding of what shapes them.” In addition the published paper makes use of additional data observed with two of the other instruments available at the JCMT.

Commenting further on this data Dr Pattle said “The JCMT is a fantastic tool: we have used data from three of the telescope’s instruments to measure how bright and how dense the region is, and what its gas and magnetic fields are doing. We see that the interaction between the head and mane of the horse and the nearby young stars has significantly reordered the magnetic field – we suggest that the magnetic field has been folded back on itself along our line of sight as the Horsehead formed. Interestingly, though, the magnetic field in the cold clump sheltered by the ridge seems not to have been affected by the interaction that created the Horsehead – it behaves exactly as we would expect magnetic fields in an isolated dense clump to do. This supports the theory that the dense clump is sheltered by the ridge. This gives us important insight into how stars can continue to form even in regions like the Horsehead, where the cold gas that provides the material for new stars is being eroded by photons from nearby young and hot stars. We expect that our own Sun formed as part of a cluster of stars, and so looking at how stars form in the Horsehead Nebula may give us an insight into our own Solar System’s past.”

As a participant of the Maunakea Scholars program Go understands that some people might be surprised to find that she is now a student at Brown University studying Public Health. Commenting on this Go said “even back in 2018 I knew I would go to college to major in Public Health but I joined the Maunakea Scholars program because it sparked my interest. That’s a personal philosophy of mine; pursue the things that interest you.”

Reflecting on the publication of the data taken back in 2018 Go said “it’s wild to see that this work is now published for other astronomers to build on. That region is even more beautiful to me now I know this story of the two clumps with subtly different stories hidden within.” And for her current career path “I love Brown University and I am really enjoying studying Public Health, I’m the Class of 2025 but I might also look at doing post-graduate studies here.”

Mallory Go (left) presenting her work on the Horsehead Nebula (right: JCMT astronomer Dr Harriet Parsons) at the Molokai High School Science Fair 2019.

Additional information

The Research

This research was published under the title “Magnetic fields in the Horsehead Nebula” by Jihye Hwang, Kate Pattle, Harriet Parsons, Mallory Go and Jongsoo Kim. It was published in the Astronomical Journal, an open access journal publishing original astronomical research, with an emphasis on significant scientific results derived from observations. A copy of the full scientific paper can be accessed at: https://iopscience.iop.org/article/10.3847/1538-3881/acc460

The data

The data obtained by Mallory in 2018 (with additional data obtained in 2019) was observed using POL-2, a linear polarimeter working at sub-mm wavelengths. Additional C18O spectral line data observed using the HARP instrument at the JCMT was also collected under the same program. This data was also used by the authors of this paper. The data were obtained under the Maunakea Scholar program under Directors Discretionary time for which the authors wish to thank Paul Ho.

Maunakea Scholars

The JCMT data presented in this paper was awarded under the Maunakea Scholars program. Maunakea Scholars is an innovative program designed to bring Hawaii’s aspiring young astronomers into the observatory community, competitively allocating observing time on world-class telescopes to local students. In particular the authors wish to thank Doug Simons and Mary Beth Laychak as leads of the Maunakea Scholars program.

Additional thanks

Additional thanks to Emilio Macalalad and Kapua Adolpho at Molokai High School.

JCMT

Operated by the East Asian Observatory, the James Clerk Maxwell Telescope (JCMT) is the largest astronomical telescope in the world designed specifically to operate in the submillimeter wavelength region of the spectrum. The JCMT has a diameter of 15 meters and is used to study our Solar System, interstellar and circumstellar dust and gas, and distant galaxies. It is situated near the summit of Maunakea, Hawai‘i, at an altitude of 4,092 meters.

The East Asian Observatory is a collaboration between our partner regions in China, Japan, South Korea, Taiwan, Thailand, the United Kingdom, Ireland, Canada, Hong Kong, Vietnam, Malaysia, and Indonesia.

The East Asian Observatory wishes to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Weather

Proposers should also be mindful of the historical fraction of time in each weather Grade in particular noting the wide variation in ours per weather Grade obtained in any one semester.

The Expanding Partner Program

PIs from Thailand, Malaysia, Vietnam, Indonesia, India, Brazil and Argentina requesting <15 hours will be automatically approved*** for time under the “Expanding Partner Program” – a program to encourage astronomers from new JCMT partners to make use of the JCMT.

*** approval reliant upon the program being technically feasible, without clashing with existing proprietary data (as per observatory requirements), dependent on weather/instrument pressures and with adjustments in line with recommendations by the TAC. Under the “Expanding Partner Program” priority will be given to new users of the JCMT.

Maunakea Hawaiʻi – JCMT astronomers studying a stellar nursery in the Taurus constellation have discovered a young dense cloud core that is in the early stages of star formation. Using observations from the JCMT and combining them with special (MHD, Magnetohydrodynamic) numerical simulations, the team was able to obtain a unique view of this star forming core called L1521F (see Figure 1).

Figure 1. Three-dimensional computer generated view of magnetic field lines (red lines), a pseudo-disk and high-density region (green surface) and out-flow (blue surface). This image enables astronomers studying the star forming core L1521F to have a greater understanding of the physical processes. In particular the (red) magnetic field lines are seen to be twisted around by the (green) high density region.

Astronomer Dr. Hiroko Shinnaga who lived and worked in Hilo, Hawaii for 11 years and was a key member of the team said “It is really exciting! These JCMT observations are capturing the moment that a star is being formed.” A computer generated model of the core has been released and is featured on the cover of the Publications of the Astronomical Society Japan (PASJ) journal of February 2023 (see Figure 1). Discussing the work, Hiroko said “When you look at the computer simulated image you see the magnetic field lines (red) are dragged by gravity along with the dust and gas. The green is the disk of the baby star (protostar) that will eventually evolve into something similar to our solar system. This green disk will create planets and moons around the baby star (like our Sun). The elongated blue feature is the so-called ‘bipolar outflow’ that is a natural byproduct of the star formation process.”

The particular star forming core, L1521F, was selected for the study by the team due to its location in the Taurus molecular cloud – a nearby star-forming cloud that harbors young stars similar in mass to our own Sun. The cloud is dark at optical wavelengths but shines brightly at submillimeter wavelengths (See Figure 2). Unlike other regions of star formation, Taurus is relatively quiet and calm with no interference from nearby massive sibling stars – enabling astronomers to study individual young stars in more detail.

Figure 2. Herschel 250 micron image of the Taurus Molecular cloud with the location of L1521F indicated. At this wavelength the cold dense dusty region shines brightly. Credit: André et al. 2010.

When asked about what makes this work unique Hiroko responded “for the first time we are able to see all the ingredients in action in forming a baby star inside L1521F – that’s very tough unless you have a telescope like the JCMT and an instrument like POL-2”. The instrument POL-2, measures the polarization of the incoming light and works with a 10,000 pixel submillimeter camera called SCUBA-2 (see Figure 3). POL-2 enables astronomers to detect magnetic fields in space at submillimeter wavelengths, a relatively new area of research in the field of star formation. POL-2 makes such sensitive measurements that it requires extraordinarily stable atmospheric conditions which makes the JCMT on Maunakea in Hawaiʻi vital for such work.

Dr. Harriet Parsons, Head of Operations at the JCMT commented “What is particularly exciting for myself as an observational astronomer is to see how we can combine the beautiful data taken with the JCMT with these powerful theoretical models. On Earth we have only one view of the cosmos, we generally cannot move closer to the objects we wish to study. These models allow us to explore the cosmos like we might experiment with a recipe in the kitchen, changing the ingredients until the model comes out just the way we see the object in the sky. It’s really exciting and a testament to the hard work of all of the team. I hope JCMT will be able to provide the team with more fantastic data in the future.“

As for the future, the team intends to study more regions like L1521F to see what is typical for such star forming cores. “Astronomers use SCUBA-2/POL-2 at JCMT to push forward to understand our Universe and our origin in the Universe.” said Hiroko “Understanding the star formation process is also essential to know how our material-rich planet, the Earth, is created. It’s incredibly exciting”.

Figure 3. Main: The JCMT, Maunakea Hawaiʻi. Top right: The interior view of the JCMT. Bottom right: the POL-2 polarimeter. Credit: William Montgomerie, Harriet Parsons, EAO/JCMT.

For those interested, the constellation Taurus is currently visible in the night sky overhead in Hawaiʻi after sunset. For those more familiar with Hawaiian starlines, the molecular cloud referenced in this work is located in Ke Kā o Makali`i (the Bailer of Makali`i) close to Makali`i (see Figure 4).

Figure 4. Optical image indicating the location of the Taurus Molecular Cloud (dark at visible wavelengths) where the L1521F cloud core is located. Credit: Akira Fujii/David Malin Images ©.

Further information

This work was published in PASJ: “Twisted magnetic field in star formation processes of L1521 F revealed by submillimeter dual-band polarimetry using the James Clerk Maxwell Telescope” by Sakiko Fukaya, Hiroko Shinnaga, Ray S. Furuya, Kohji Tomisaka, Masahiro N. Machida, and Naoto Harada. An online video explaining the work in more detail may be viewed here.

With credit to the following institutions:

Physics and Astronomy Department, Graduate School of Science and Engineering, Kagoshima University, Japan. Amanogawa Galaxy Astronomy Research Center (AGARC), Graduate School of Science and Engineering, Kagoshima University, Japan. Institute of Liberal Arts and Sciences, Tokushima University, Japan. National Astronomical Observatory of Japan. Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Japan.

The team

Computational power

The special (MHD, Magnetohydrodynamic) numerical simulations require a vast computational effort. The team calculated 9 models and chose the model that best fitted to observations of L1521F. Each model requires about 40,000 CPU hours using a vector type supercomputer. After the models are created polarization and intensity distributions are created for 24 different viewing angles.

Related work

“Misalignment of magnetic fields, outflows, and discs in star-forming clouds” Masahiro, Shingo and Hideyuki 2020 MNRAS https://ui.adsabs.harvard.edu/abs/2020MNRAS.491.2180M/abstract

About the James Clerk Maxwell Telescope

Operated by the East Asian Observatory, the James Clerk Maxwell Telescope (JCMT) is the largest astronomical telescope in the world designed specifically to operate in the submillimeter wavelength region of the spectrum. The JCMT has a diameter of 15 meters and is used to study our Solar System, interstellar and circumstellar dust and gas, and distant galaxies. It is situated near the summit of Maunakea, Hawai‘i, at an altitude of 4,092 meters.

The East Asian Observatory is a collaboration between our partner regions in China, Japan, Korea, Taiwan, Thailand, United Kingdom, Canada, Hong Kong, Vietnam, Malaysia, and Indonesia. Click here for more information.

The East Asian Observatory wishes to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Contacts

Dr. Harriet Parsons, JCMT Head of Operations, EAO/JCMT h.parsons@eaobservatory.org

Dr. Hiroko Shinnaga, shinnaga@sci.kagoshima-u.ac.jp

On November 23rd (HST) the JCMT participated in Frequency Phase Transfer (FPT) testing with the SMA, KVN Yonsei, GLT and IRAM 30m. During high frequency Very Long Baseline Interferometry (VLBI) observations the atmosphere can heavily impact the phases of radio signals and reduce the coherence time (leading to degradation in data quality). By observing with multiple frequencies this effect can be calibrated enabling higher data quality for astronomer. This testing had JCMT staff working with staff at other facilities to observe VLBI at  both 214.1 – 261.1GHz (using `Ū`ū, LSB at JCMT) and 86-88 GHz (using `Alaihi, USB at JCMT) for the first time.

Additionally JCMT participated in the East Asian VLBI Network (EAVN) for the first time on the nigh of November 25th (HST) with KVN Yonsei, and GLT. Getting ready for these two nights of VLBI observing was an observatory wide effort from our engineering team, instrument team, software and science team ensuring everything was ready for a smooth run.

The FPT observing team from JCMT, SMA, KVN Yonsei, and IRAM 30-m. Image credit: Sara Issaoun

For those interested the FPT technique has been broadly discussed in e.g. Rioja & Dodson (2011).