Call for Proposals 19B

The East Asian Observatory is happy to invite PI observing proposals for semester 19B at the JCMT. Proposal submission is via the JCMT proposal handling system, Hedwig. For full details, and for proposal submission, please see

The 19B Call for Proposals closes on the 15th of March, 2019.

If this is your first time using Hedwig, you should ‘Log in’ and generate an account. There is a Hedwig ‘Help’ facility at the upper right corner of each page, and individual Help tags in many other places.

Please contact us at if you have remaining questions.

– 20190215

JCMT Transient Survey Team Observes Record-Breaking Flare

On November 26th, 2016, the JCMT Transient Survey Team observed what is estimated to be the most luminous known flare associated with a young stellar object. It is also the first coronal flare discovered at submillimetre wavelengths. The brief flash of light occurred in the direction of a binary system of forming stars known as “JW 566” in the Orion Nebula and it carried ten billion times the amount of energy of the solar flares observed around the Sun.

Left: The Orion Nebula as seen by SCUBA-2 at 850 microns. Right: Two images of
the field surrounded by the green square taken 6 days apart. Small rectangles/triangles show the
positions of known young stars found by other telescopes. On November 20th, 2016, there was
no signal. On November 26th, 2016, the flare was observed while it was already dimming from
its (unseen) maximum brightness.

The flare was discovered by JCMT support astronomer Dr. Steve Mairs using advanced image analysis techniques that had been developed by the Transient Survey team over the past 2 years. The SCUBA-2 observations lasted approximately 30 minutes over which time  the flare faded to half of the brightness measured at the beginning of the scan, indicating the event was short-lived. The flare is thought to be caused by an intense magnetic field re-connection event that energised charged particles to emit gyrosynchrotron/synchrotron radiation.

Press Release: Sky and Telescope, Hawai’i Tribune Herald, Big Island News

Publication: ArXiv, ApJ

The JCMT Transient Survey Team

The JCMT Transient Survey team is an international collaboration of 80 astronomers led by Dr. Gregory Herczeg of Peking (Kavli Institute for Astronomy and Astrophysics) and Dr. Doug Johnstone (National Research Council of Canada). The team has been monitoring 8 star-forming regions in the Milky Way with a monthly cadence since December, 2015. The survey will continue through January, 2020.

The Brightest Quasar in the Early Universe

Observations obtained by the JCMT helped uncover the Brightest Quasar in the Early Universe!

The light from Quasar J043947.08+163415.7 is gravitationally lensed by a dim Galaxy in the foreground, allowing Fan et al. (2019, APJL: 870, 11) to get a good look at this active galactic nucleus at a redshift of z = 6.51 (A distance of ~12.8 Billion Light years!). As the authors note, “This is the first such object detected at the epoch of reionization, and the brightest quasar yet known at z > 5”.

The JCMT is instrumental in observing distant star-forming galaxies. These galaxies have high concentrations of dust that reprocess the starlight such that it is emitted at infrared wavelengths. The light is then redshifted due to the expansion of the universe into the submillimetre regime. The star formation rate is estimated to be 10,000 times higher than that of our own Galaxy, the Milky Way.

Press Release:

Astronomers uncover the brightest quasar in the early universe


The Discovery of a Gravitationally Lensed Quasar at z = 6.51

An artist’s rendering of a distance quasar (Credit: ESO/M. Kornmesser

A bit of history…

The name “Quasar” is a shortened version of the original designation scientists gave to a mysterious signal we didn’t have a scientific interpretation for: a “quasi-stellar radio source” discovered in 1963 by Maarten Schmidt.

Over decades of intensive studies, astronomers have been able to determine that these mysterious signals were coming from intense bursts of light in the hearts of galaxies far, far away.

Most (maybe all!) galaxies contain a supermassive black hole millions to billions times the mass of our Sun. In some of these galaxies, infalling material gets too close to the black hole and it heats up to millions of degrees, exploding outward in a massive release of energy!

We can detect those signals, which we now affectionately call Quasars, at submillimetre wavelengths with the JCMT.

Congratulations to Dr. Xiaohui Fan and his co-authors !

Discovering the Cosmic Nurseries of Giant Elliptical Galaxies

The birth of giant elliptical galaxies is a violent process, with most stars originating from incredible star-forming episodes and several galaxy mergers within large-scale structures (dubbed protoclusters). This formation process happened in the early epochs, when the Universe was only a few billion years old. Currently, researchers using the James Clerk Maxwell Telescope (JCMT) on Maunakea, Hawaiʻi are trying to locate the progenitors of elliptical galaxies, and thus protoclusters, using several observational techniques.

Astronomers have recently discovered a handful of rare, enormous nebulae that copiously emit in the Hydrogen Lyman-alpha transition, a tracer of intergalactic gas. These emissions cover vast distances, up to 30 times larger than the Milky Way. Most of these Enormous Lyman-Alpha Nebulae (ELANe) host multiple active galactic nuclei and are surrounded by several Lyman-alpha emission galaxies. These ELANe are prime candidates for progenitors of elliptical galaxies and massive protoclusters in the early stages of assembly. While these regions are promising, researchers are now tasked with determining the presence of protoclusters and of heavy star formation associated with each ELAN.

An international team of researchers started using the SCUBA-2 instrument on JCMT to characterize these protoclusters and the associated ELAN. Observing at 450 and 850 microns allows SCUBA-2 to capture the emission from dust powered by violent episodes of star formation, something that is not possible with optical telescopes.

Results from the targeted ELAN MAMMOTH-1 field (Fig. 1) revealed the presence of a violent starburst galaxy and emission from a veiled active galactic nuclei (Fig. 2). These sources likely power the extended Lyman-alpha emission, and could be the progenitor of an elliptical galaxy.

In addition, researchers find four times the number of dust-obscured sources in ELAN
MAMMOTH-1 compared to other standard regions. This likely confirms the presence of a rich structure surrounding ELAN MAMMOTH-1, and hints at the presence of a protocluster, hosting the progenitor of an elliptical galaxy. Figure 3 shows the distribution of Lyman-alpha emitting galaxies compared to the SCUBA-2 detections within the observed field. Hopefully, follow-up observations will confirm the relationship between these newly detected sources and a protocluster surrounding the ELAN. For now, these findings seem to agree with the expected theoretical characterizations of cosmic nurseries of giant elliptical galaxies.

Figure 1: ELAN MAMMOTH-1 at z=2.3. This figure shows the surface brightness map (in units of erg/s/cm2/arcsec2) of the Hydrogen Lyman-alpha emission of the ELAN MAMMOTH-1 using a custom-made narrow-band filter. The map is color-coded following the level of surface brightness (see colorbar on the left). The nebula is clearly extended on intergalactic scales (hundreds of projected kiloparsecs; see yellow scale). The red star indicates the position of the likely powering source of this extended emission (see Figure 2). This figure was adapted from Cai et al. (2017). Image Credit: Arrigoni Battaia F., Cai Z.

Figure 2: Spectral energy distribution for the source powering the ELAN MAMMOTH-1. The data-points are from Large Binocular Camera (Large Binocular Telescope) imaging and the Wide-field InfraRed Camera (United Kingdom Infrared Telescope) (Cai et al. 2017 and Xu et al. in prep.; blue), AllWISE source catalog (Wright et al. 2010; orange), the SCUBA-2 (JCMT) observations (magenta), and the FIRST survey (Becker et al. 1994; green). The SCUBA-2 data are key in constraining the spectral energy distribution of this source, allowing researchers to infer the presence of an obscured active galactic nucleus and of intense star formation of the order of 400 solar masses per year. Indeed, the grey line is the best fit model which includes a hot-dust emission component inherent of active galactic nuclei and a strong dust emission likely powered by intense star formation. This figure was adapted from Arrigoni Battaia et al. (2018) Image Credit: Arrigoni Battaia F./European Southern Observatory.


Figure 3: Location of known sources surrounding the ELAN MAMMOTH-1. The small black circles indicate the known galaxies emitting Lyman-alpha emission within the known galaxy large-scale structure surrounding the ELAN MAMMOTH-1. The brown crosses indicate the quasars within such large-scale structure. The large blue circles and yellow squares indicate the sources detected within the two bands of the SCUBA-2 instrument, 850 and 450 microns respectively. The orange diamonds indicate the only two sources with both Lyman-alpha emission and SCUBA-2 detection. One of them is the ELAN MAMMOTH-1. The number of detected sources at 850 microns in the SCUBA-2 data reveals four times more dust-obscured sources than in “standard” regions, likely confirming the presence of a rich protocluster surrounding the ELAN MAMMOTH-1. The brightest of the SCUBA-2 detections coincide with the peak of the known galaxy distribution (traced by the green contours) within this large-scale structure (numbers close to each blue circle indicate the flux at 850 microns). This figure was adapted from Arrigoni Battaia et al. (2018) Image Credit: Arrigoni Battaia F./European Southern Observatory.

Media Contacts:

European Southern Observatory/Max-Planck Institute for Astrophysics
Fabrizio Arrigoni Battaia
farrigon at

European Southern Observatory
Chian-Chou Chen
ccchen at

James Clerk Maxwell Telescope
Harriet Parsons
h.parsons at

About The Authors

The international authors of this paper are from European Southern Observatory, Germany, Durham University, UK, University of California, USA, Leiden University, Netherlands, Tsinghua University, China, and the Korea Astronomy and Space Science Institute, South Korea.



Observing Comet 46P/Wirtanen from the JCMT

Comet 46P/Wirtanen is known as a hyperactive comet. Hyperactive comets are a small family of comets whose activity levels are higher than expected. In addition to being hyperactive 46P/Wirtanen will make the 10th closest ever cometary approach to Earth of modern times (0.08au) this month.

JCMT with Comet 46P/Wirtanen. Credit: EAO/JCMT/Kevin Silva

JCMT astronomers will take this opportunity to map the distribution of chemicals like hydrogen cyanide and methanol in this comet’s coma, to try and determine if these chemicals emerged directly from the comet nucleus or were formed in the coma from other chemicals. This mapping will be performed by the JCMT spectral line instrument; HARP. In addition to observing these chemicals the astronomers are hoping the comet will be bright enough to  make other measurements that that will shed light on the original location and conditions of the comet’s formation within the very early stages of what we now know to be our Solar System.

JCMT comet hunters Iain Coulson, Yi-Jehng Kuan, Fang-Chun Liu along with Support Astronomer (Steve Mairs)

For more information on comet 46P/Wirtanen visit:

Comet 46P/Wirtanen from the NASA Astronomy Picture of the Day 2018 November 15, Image Credit & Copyright: Alex Cherney (Terrastro, TWAN).

Maunakea Gender Equity and Diversity Survey 2018 Report

In July 2018, the Maunakea Gender Equity and Diversity Committee distributed a survey to the staff at the Maunakea astronomical organizations. The survey was intended to invite opinion on the current state of equity and diversity in the Maunakea astronomy community and seed conversation and ideas for enhancing diversity and inclusion in our organizations across our islands.

The report on the results of the survey is here:

Maunakea Gender Equity and Diversity Survey 2018 Report

and the Appendix A, listing the survey questions, is provided for reference:

Gender Equity and Diversity Survey questions

The first results are presented by Jessica Dempsey at the Maunakea Users’ Meeting on October 4th, 2018. A PDF of the talk is linked here for convenience. For usage or distribution of these data, please contact Jessica Dempsey: j.dempsey “at”

Photo by Oro Whitley

– 20181004


Discovering Magnetized Inflow Accreting to the center of Milky Way Galaxy – An important force to transport gas to the supermassive black hole Sagittarius A*

Is magnetic field an important guiding force for gas accreting to supermassive black hole (SMBH) — for example, the one that our Milky Way Galaxy hosts? The role of magnetic field in this subject is little understood and trying to observe it has been challenging to astronomers. Researchers at the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan, led by Dr. Pei-Ying Hsieh, have utilized a measurement of high resolution data by using the instruments on the James Clerk Maxwell Telescope (JCMT). Their result provides clear evidences in showing that the orientation of the magnetic field is in alignment with the molecular torus and ionized streamers rotating with respect to Sagittarius A* – the black hole our home galaxy hosts. The findings are published in Astrophysical Journal in 2018 August 2nd (2018, ApJ, 862, 150).

Color-composite images of the SMA map tracing the molecular gas of the CND (blue) and the Very Large Array (VLA) 6 cm map tracing the mini-spiral (red). The magnetic field of the JCMT-SCUPOL data and the model are overlaid with the white segments in the upper right and low left panel, respectively. The location of SgrA* is labeled with the black cross. The CND is a molecular torus (ring) rotating with respect to the supermassive black hole SgrA* in our Galaxy. The mini-spiral is hypothesized to be originated from the inner edge of the CND. The alignment of the magnetic field line along with the CND and the mini-spiral tells us that they are linked with a coherent magnetic field. The team found the magnetic field is able to guide the ionized particles from the CND to the mini-spiral, which suggests a picture the footprint of inflow near SgrA*. In the lower right panel, the latest dust polarization data taken in 2017 measured with the new instruments POL-2 installed in JCMT is shown. The magnetic field is shown with the white segments. An improved spatial coverage and sensitivity clearly reveal the connection between the CND and the mini-spiral at even higher spatial sampling than the JCMT-SCUPOL data, which confirm the picture the team proposed.

SgrA* – the best laboratory to study black hole feeding in the sky

Sagittarius A* (SgrA*),  being the closest SMBH in our home in the universe, the Milky Way Galaxy, has been targeted by many scientists to understand the nature of gas accretion in the past decades. Observing the gas accretion onto SMBH is critical to help us to understand how it releases tremendous energy.

The circumnuclear disk (CND) is a molecular torus rotating with respect to SgrA*, within which are the ionized gas streamers called mini-spiral (also called SgrA West) filling the molecular cavity. The mini-spiral is hypothesized to be originated from the inner edge of the CND. The CND, being the closest “food reservoir” of SgrA*, is therefore critical on the understanding of the feeding of SgrA*. However, looking for the physical evidences to connect the CND and the mini-spiral puzzles astronomers since they were discovered a few decades ago.

Intensive measurements of dynamical movements orbiting SgrA* have been done in the past decades, but another important force – the magnetic field – is rarely probed. This is solely because the weak polarized signal generated by the magnetic field from dust emission is difficult to measure. However, the magnetic field is expected to be important for material orbiting within and around the CND as the magnetic stress acting on the rotating disk can exert a torque to extract angular momentum from rotating gas, and thus drive gas inflows. Besides, The magnetic tension force is also possible to draw the gas back from the gravitational pull. Taking advantage of excellent atmospheric conditions of Mauna Kea summit at 4000 m, and large aperture size of the JCMT (15 m in diameter), the submillimeter polarization experiments were successfully obtained toward the Galactic Center to understand the role of magnetic field.

Tracing Magnetized Accreting Inflow

The team utilized the dust polarization data obtained by the JCMT-SCUPOL instrument to image the orientation of the magnetic field. A detailed comparison with higher-resolution interferometric maps from the Submillimeter Array (SMA) reveals that the magnetic field aligns with the CND.  Moreover, the innermost observed magnetic field lines also appear to trace and align with the mini-spiral coherently. This is the first attempt to reveal the footprint of inflow linking the CND and the mini-spiral since they were discovered a few decades ago. The comparison of the model and data reinforces the key idea that the CND and the mini-spiral can be treated as a coherent inflow-system.

The team found that the magnetic field is dynamically significant towards the CND and the mini-spiral. This finding tells us that the magnetic field is able to guide the motion of the ionized particles originated in the CND, and produce the observed spiral pattern of the mini-spiral. Dr. Hsieh said, “We found the magnetic field is critical to explain the inflow structure and will also help to understand the inflow picture in other galaxies hosting black hole similar to SgrA*. “

Paper and research team:

These observation results were published as Hsieh et al. “A Magnetic Field Connecting the Galactic Center Circumnuclear Disk with Streamers and Mini-spiral -Implications from 850 micron Polarization Data” in the Astrophysical Journal (published in the Astrophysical in August 2nd).

This research was conducted by:

Hsieh, Pei-Ying (ASIAA); Koch, Patrick M. (ASIAA); Kim, Woong-Tae (SNU); Ho, Paul T. P. (ASIAA; EAO); Tang, Ya-Wen (ASIAA); Wang, Hsiang-Hsu (CUHK)

This research is supported by the Ministry of Science and Technology (MoST) of Taiwan through the grants MoST 105-2811-M-001-141, MoST 106-2811-M-001-136, MoST 104-2119-M-001-019-MY3, MOST 105-2112-M-001-025-MY3, Academia Sinica Career Development Award, and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST; No. 3348-20160021).

Related Links:


Call for Proposals 19A

The East Asian Observatory is happy to invite PI observing proposals for semester 19A at the JCMT. Proposal submission is via the JCMT proposal handling system, Hedwig. For full details, and for proposal submission please see

The 19A Call for Proposals closes on the 15th of September, 2018.

If this is your first time using Hedwig, you should ‘Log in’ and generate an account. There is a Hedwig ‘Help’ facility at the upper right corner of each page, and individual Help tags in many other places.

Please contact us at if you have remaining questions.

– 20180815

CHIMPS-2 members meet in Liverpool

Members of the CHIMPS-2 Large Program met for a two day meeting in Liverpool on June 28th and 29th. The meeting covered data collection, reduction and analysis with astronomers from all over the globe. For more information on the CHIMPS-2 project click here. We wish the team “clear skies” as they look to expand the JCMT CO heterodyne data towards the Galactic Centre this summer.

– 20180708

First observations of the magnetic field inside the Pillars of Creation: Results from the BISTRO survey

The BISTRO (B-Fields in Star-Forming Region Observations) Survey has for the first time mapped the magnetic field in the dense gas of the ‘Pillars of Creation’, using instruments on the James Clerk Maxwell Telescope (JCMT). The Pillars of Creation, in the Messier 16 star-forming region, which is also known as the Eagle Nebula, were the subject of one of the most iconic images taken by the Hubble Space Telescope (HST). The Pillars are a set of columns of cold, dense gas protruding into a region of hot, ionized plasma. The Pillars have nurseries of new stars forming at their tips, and are a particularly dramatic example of a feature found in many regions of interstellar space in which high-mass stars are forming.

We present the first high-resolution observations of the Pillars in polarized light at submillimeter wave- lengths – submillimeter light being on the cusp between infrared and radio waves, where the cold, dense dust and gas which will form the next generation of stars emits most of its light. Light emitted from these dusty regions is polarized perpendicular to the direction of its local magnetic field, and so we can use our observations to directly probe the magnetic field morphology within the dense gas of the Pillars of Creation. Our observations were taken at a wavelength of 0.85 mm as part of the BISTRO Survey, using the POL-2 polarimeter on the SCUBA-2 submillimeter camera at the JCMT. They show that the magnetic field runs along the length of the pillars, at a significantly different angle to the field in the surrounding ionized plasma, and has an estimated strength of approximately 170 − 320 microGauss (1.7 − 3.2 × 10−8 Tesla), an intermediate magnetic field strength for a region of space which is forming stars.

An illustrative figure of the BISTRO magnetic field vectors observed in the Pillars of Creation, overlaid on a HST 502 nm, 657 nm and 673 nm composite – HST imaging from Hester et al. (1996, AJ 111, 2349).

Young hot stars, with masses more than eight times that of the Sun, produce large numbers of high-energy photons. These high-energy photons ionize a volume of the region within which they form, splitting hydrogen atoms into pairs of protons and elections. As the shock front between the material ionized by the young stars and the untouched neutral material advances, complex structures form in the dense gas at the interface. Particularly, pillars of dense, neutral gas like those in M16 are found protruding into the ionized region, apparently left behind by the advancing shock front. The formation and evolution of these pillars is not well-understood – debate continues as to whether these pillars form behind obstructions to the shock front, or whether they can form from turbulent instabilities in the shock front itself. The role of the magnetic field in the formation of the Pillars is particularly uncertain, since the strength of the magnetic field in the dense parts of the Pillars has not been measured until now.

BISTRO magnetic field vectors overlaid on a HST 502 nm, 657 nm and 673 nm composite image of Pillar II. The magnetic field runs roughly parallel to the Pillar’s axis. No polarization is detected at the Pillar’s tip – this depolarization is consistent with a horseshoe-shaped magnetic field morphology on scales smaller than the beam.

Our observations of the magnetic field running along the length of the Pillars are consistent with the Pillars being formed by compression of gas with an initially weak magnetic field: the magnetic field has not had the strength to resist being dragged into its current configuration by the motions of the gas. However, the magnetic field strength appears to have been increased by being compressed in the forming pillars. The magnetic field strength that we estimate is large enough to magnetically support the sides of Pillars against collapsing radially under pressure from the surrounding hot plasma, and to prevent the Pillars collapsing under their own gravity. It is important to note though that the Pillars are still being destroyed by the same shock interaction that created them: the magnetic field that we measure is not strong enough to prevent the Pillars being gradually eroded from their tips by the effects of the young stars in the region. Our results suggest that the evolution and lifetime of the Pillars may thus be strongly influenced by the strength and orientation of their magnetic field: the Pillars’ longevity results from magnetic support.

Our proposed evolutionary scenario: (a) an ionization front moving perpendicular to the am- bient magnetic field approaches an existing over-density in the molecular gas. (b) The ionization front is slowed by the over-density. The flux-frozen magnetic field ‘bows’ into the forming pillar. (c) The com- pressed magnetic field supports the pillar against further gas-pressure- and gravity-driven radial collapse, but cannot support against longitudinal erosion of the over-density by ionizing photons. Throughout, dark blue shading represents molecular gas and light blue shading represents ionized material. The ionization front is shown as a black line. Grey dashed lines indicate the local magnetic field direction. Red arrows represent photon flux, black arrows represent magnetic pressure, and green arrows represent thermal gas pressure.

The James Clerk Maxwell Telescope, located on Mauna Kea in Hawaii, is operated by the East Asian Observatory. The BISTRO Survey is a large team of scientists working to understand the role of mag- netic fields in the formation of stars, with members from across the partner regions of the East Asian Observatory: China, Japan, South Korea, Taiwan and Vietnam, and from participating universities in the United Kingdom and Canada.

This research has been accepted for publication by The Astrophysical Journal Letters. A pre-print is available at

Kate Pattle, Derek Ward-Thompson, Tetsuo Hasegawa, Pierre Bastien, Woojin Kwon, Shih-Ping Lai, Keping Qiu, Ray Furuya, David Berry and the JCMT BISTRO Survey Team

Inquiries about this research: Email:

The “Pillars of Creation” is one of the most well-known images in astronomy, and it is very exciting to be able to add to what is known about this part of the sky.  The pillars are beautiful structures – remarkable for their highly coherent structure within the dynamic and highly energetic environment of a region forming high-mass stars.  We have found that the magnetic field within the Pillars is well-ordered, running along the length of the pillars, and is strong enough to influence the future evolution of the pillars, helping to support them against collapse.  This is an intriguing result because it shows us that the magnetic field is important to the region now, but also that it was likely not very important during the period when the pillars were forming.  The field appears to have changed significantly from its original direction to run along the pillars as they were formed by a shock interaction caused by nearby young stars.  This could not have happened if the magnetic field were strong enough to resist being moved.  Our results suggest that the importance of the magnetic field to the Pillars of Creation has evolved over time along with the Pillars themselves.

The JCMT is the only telescope in the world which could have made these observations – the JCMT’s POL-2 polarimeter and SCUBA-2 camera are a unique combination of instruments, observing at the wavelengths at which cold dust in star-forming regions emits most of its light.  POL-2 provides information on the magnetic field on the scale of objects such as the Pillars of Creation which is not available anywhere else.

We have already had a proposal accepted by the Submillimeter Array (SMA) on Mauna Kea to observe the magnetic field in the tips of the pillars in more detail.  In our JCMT observations we see the magnetic field disappear at the tips of the pillars.  This “depolarization” could be caused by tangled magnetic field lines or a complete reversal of magnetic field direction in the pillars’ tips causing the field to cancel out in our observations.  By observing at higher resolution with the SMA we will be able to see what the magnetic field looks like on these small scales, and to better understand what role the magnetic field is playing in the shock interaction which is driving the pillars’ evolution.  We could also potentially look in more detail still at the magnetic field in clumps in the pillars’ tips using the Atacama Millimeter/submillimeter Array (ALMA) in Chile, or observe the pillars in polarized near-infrared light using the airborne SOFIA observatory.


Call for Proposals 18B

The East Asian Observatory is happy to invite PI observing proposals for semester 18B at JCMT. Proposal submission is via the JCMT proposal handling system, Hedwig. For full details, and for proposal submission please see

The 18B Call for Proposals closes on the 15th of March, 2018.

If this is your first time using Hedwig, you should ‘Log in’ and generate an account. There is a Hedwig ‘Help’ facility at the upper right corner of each page, and individual Help tags in many other places.

Please contact us at if you have remaining questions.

– 20180214

18-month twinkle in a forming star suggests
 the existence of a very young planet

Discovery made possible by a leap in submillimetre radio astronomy technology,
 comparable to viewing videos instead of photos.

November 1, 2017 — An international team of researchers have found an infrequent variation in the brightness of a forming star. This 18-month recurring twinkle is not only an unexpected phenomenon for scientists, but its repeated behavior suggests the presence of a hidden planet.

This discovery is an early win for the James Clerk Maxwell Telescope (JCMT) Transient Survey, just one-and-a-half years into its three-year mandate to monitor eight galactic stellar nurseries for variations in the brightness of forming stars. This novel study is critical to understanding how stars and planets are assembled. The survey is led by Doug Johnstone, Research Officer at the National Research Council of Canada and Greg Herczeg, Professor at Peking University (China), and is supported by an international team of astronomers from Canada, China, Korea, Japan, Taiwan and the United Kingdom.

“This variation in the brightness or twinkle of the star EC53 suggests that something large is disrupting the gravitational pull of the forming star. The fact that it recurs every 18 months suggests that this influence is orbiting around the star – it’s quite likely a hidden, forming planet,” says Doug Johnstone. It is thought that a companion planet is orbiting the star, and its passing gravitational pull disrupts the rate of the gas falling onto the forming star, providing a variation in the observed brightness, or light curve, of the star.


Young stars are born in regions of the galaxy where molecular gas is abundant. When the star is young, gas and dust form a thick cloud that surrounds the star. Some of this material quickly flattens into a disk, in which planets will form. The cloud blocks the star itself from optical view, so astronomers study the star indirectly by using the cloud to learn details about the star growing inside. The star builds up its mass as gravity attracts gas to move from the disk onto the star, a process that also releases significant energy that heats up the surrounding gas cloud. Astronomers use telescopes sensitive to sub-millimetre wavelengths, like the JCMT, to measure the cloud brightness and reveal details about the growth of the star.

EC53’s light curve anomaly was discovered by Hyunju Yoo, graduate student at Chungnam National University and advisor Jeong-Eun Lee, Professor at Kyung Hee University (South Korea), through careful analysis of monthly observations of Serpens Main, a stellar nursery known to contain many forming stars. Although the brightness of EC53 has been observed to vary periodically at near-infrared wavelengths for some time, these sub-millimetre observations were essential in validating that the brightness variation was due to heating from gas accreting onto the forming star, rather than variations in the cloudiness of the environment.

“What caught my eye was a new round of data that showed a sudden brightness that hadn’t existed in previous observations,” says Lee. “I knew that something unique and interesting must be happening around this forming star. It turned out that it is indeed a very special object, providing a new window into how stars and planets form.”

A deeper understanding of the formation of stars and planets

For the remainder of the three-year sub-millimetre survey, the team will continue to monitor EC53 and will also be searching for additional young stars showing variations in growth to learn more about how stars and planets assemble. There are already a half-dozen additional candidate variables within the survey. By studying these stars, and using additional telescope facilities such as the powerful Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the study will provide new and unique insight into the timescale for the formation of stars and planets, including whether planets form during or after the assembly of the star.

“This discovery marks a turning point; in a sense, it’s like sub-millimetre astronomy is moving from taking pictures of our galaxy to taking videos,” says Greg Herczeg. “The last 25 years have been devoted to perfecting observing techniques and instruments to allow us to see early star formation. But with recent advances in technology, we can now observe regions changing over time, for a deeper understanding of how stars form. This discovery is just one example of how much more we can now learn.”

Monitoring the brightness of forming stars over time using sub-millimetre wavelengths is an unconventional approach to observing that has been made possible by recent advances in imaging technology, like SCUBA-2, and data reduction processing which enables precise calibration and measurement.

The JCMT resides at the summit of Maunakea in Hawaii and is the largest single-dish sub- millimetre telescope in the world. The JCMT is operated by the East Asian Observatory, a partnership between China, Taiwan, South Korea and Japan, with support from the astronomy communities in Canada and the United Kingdom. The university-led contributions from Canada are supplemented by the NRC’s support for the JCMT archive at the Canadian Astronomy Data Centre.

This discovery has been accepted for publication in Astrophysical Journal and is available online.

This story is distributed on behalf of: The National Research Council of Canada, Peking University and Kyung Hee University.


Media Relations Team
National Research Council of Canada
1-855-282-1637 (in Canada)
1-613-991-1431 (elsewhere in North America)
001-613-991-1431 (International)
Twitter: @nrc_cnrc

The Kavli Institute for Astronomy and Astrophysics (KIAA)
Peking University
Shuyan Liu

Kyung Hee University
Min-Jae Jung
Communications team

James Clerk Maxwell Telescope
Steve Mairs

– 20171101

“Stray Black Holes” discovered in the Galactic Centre

A research team led by Japanese astronomers using data taken with the James Clerk Maxwell Telescope (JCMT), have conducted detailed radio spectral observations of molecular gas around the nucleus of our Milky Way Galaxy, Sgr A*.

As a result, the team has discovered two compact molecular clouds that have extremely broad velocity widths at distances of approximately 20 light years from Sgr A*. Despite the fact that these peculiar clouds have large kinetic energies, no energy source has been found there. Thus, the team interprets that each of the clouds is driven by the high-velocity plunge of an isolated (invisible) black hole without a companion star into a giant molecular cloud.  This implies that multiple “stray black holes” are floating around a supermassive black hole lurking at the Galactic center.

Illustration of stray black holes floating around a supermassive black hole at the Galactic center.

1. Important Points

  • The team studied two unusual molecular clouds. These two clouds were discovered in the vicinity of the Galactic nucleus of the Milky Way, Sgr A*.  Their motions and physical properties were studied and their motions were deemed to be abnormal.
  • The origin of each of unusual clouds cannot be explained by an interaction with a supernova. The clouds are also not explained by a bipolar outflow from a protostar. This implies that the origin is likely to be an obscure astrophysical phenomena.
  • As a result of the large kinetic energies observed combined with no a lack of an obvious energy source, the team theorizes that the driving sources may be black holes rapidly plunging into molecular clouds.

2. Research Background

The Galactic nucleus Sgr A* is located at a distance of approximately 26,000 light years from the Earth, and recognized as a supermassive black hole with 4 million solar masses. The origin of the supermassive black hole remains unresolved. In contrast, a stellar mass black hole, which has a mass ranging from about three to several tens of solar masses, is known to be formed by the gravitational collapse of a massive star heavier than 30 solar masses. It is theoretically predicted that several hundred million stellar mass black holes lurk in the Milky Way.

However, the number of black hole candidates currently detected in the Milky Way is only 60. In general, gas and dust drawn by the gravitational force of a black hole constitute an accretion disk around it. After the materials are sufficiently accreted and the accretion disk gets hotter and emits intense electromagnetic waves. Typically stellar mass black holes in the Milky Way have been found by detection of X-ray radiation from their accretion disks. In order for an accretion disk to be continuously shining, a fueling source, i.e. a companion star, must be in the close vicinity of a black hole. However, such black holes (those with close companions) are very rare. Most of back holes are likely to be isolated and inactive. Thus, countless “stray black holes” should be floating in the Milky Way.

3. Research Results

The research team conducted spectral line observations of the Galactic central region within 30 light years of the Galactic nucleus Sgr A* to investigate kinematics and physical properties of molecular gas surrounding the nucleus, using the JCMT. In the observations, the team discovered two unusual molecular clouds (HCN–0.009–0.044 and HCN–0.085–0.094) with diameters of about 3 light years and extremely broad velocity widths wider than 40 km/s (See Figure b below). Each of these unusual clouds appears to stem from a larger cloud. Their motions seem to be different from those of well-known molecular clouds around the nucleus (See Figure a, and c below).

These motions imply enormous kinematic energies (>1047 erg). Such enormous kinetic energy may be produced by an interaction with a supernova explosion or a bipolar outflow form a bright massive protostar. However, no evidence of a supernova or a bright protostar was found toward these peculiar clouds.   The origin is probably “something” other than well-known astrophysical phenomena; inactive stellar mass Black Holes.

The data used to make this discovery (a) Position-velocity diagram along the yellow vertical line in the panel (b). (b) Integral intensity map of the Galactic central region around Sgr A* (shown by a white star) in the hydrogen cyanide (HCN) 354.6 GHz spectral line. The light-blue cross marks indicate the locations of the discovered peculiar compact clouds (HCN–0.009–0.044 and HCN–0.085–0.094). (c) Position-velocity diagram along the yellow horizontal line in the panel (b). (d, e) The spectral lines detected toward the peculiar clouds.

The team proposes that the high kinematic energy results from: “a high-speed compact gravitational source plunging into a molecular cloud and the gas is dragged along by the gravity of the compact source to form a gas stream.”

According this “plunge scenario”, such unusual clouds can be formed in two cases as follows:

  • A massive compact object with a mass larger than about 10 time the mass of our Sun plunges with a high velocity of about 100 km/s into a molecular cloud.
  • A compact object with a mass similar to that of the Sun plunges with a ultra high velocity of about 1000 km/s into a molecular cloud.

In the case 1), the candidate for the plunging object is a massive star or black hole. In the case 2), the candidate is a hypervelocity star which moves so fast that it can escape from the gravity of the Galaxy. However, no hypervelocity star has been found in the Galactic center and the number is theoretically predicted to be much less than that of black holes. Therefore, the driving sources of the two discovered clouds are likely to be massive stars or black holes. In addition, no bright massive stars have been found toward these clouds. Thus, a “stray black hole” floating around the supermassive black hole is the most plausible candidate for each of the driving sources of the two clouds.

4. Research Significance

This work is very meaningful since the possibility that a number of “stray black holes” are floating around a supermassive black hole at the Galactic center was indicated by the observational study for the first time.

The team has already discovered the peculiar molecular cloud in the Galactic disk (Bullet) that may also be driven by a high-velocity plunge of a stray black hole (Yamada et al. 2017,

These studies which are based on spectral line observations of molecular gas suggest a new method of potentially discovering inactive isolated black holes that are undetected by traditional method such as X-ray observations. The number of black hole candidates is expected to dramatically increase by applying research methods similar to this work.

Recently, by detection of gravitational waves, it has been confirmed that black holes merge and grow. The team has also discovered a candidate for an intermediate mass black hole with a mass of 100 thousand solar masses at a distance of about 200 light years from the Galactic nucleus

(Oka et al. 2017,

This intermediate mass black hole and stray black holes discovered in this work possibly contribute to growth of the supermassive black hole in future.

Inquiries about the research

Professor Tomoharu Oka
Department of Physics
Keio University Science and Technology
TEL: +81-45-566-1833 FAX: +81-45-566-1833


These observation results were published as Takekawa et al. “Discovery of Two Small High-velocity Compact Clouds in the Central 10 pc of Our Galaxy” in the Astrophysical Journal Letters in July 2017.

The team behind this work are Shunya Takekawa, a Ph.D. student at Keio University, Japan, and Tomoharu Oka, a professor at Keio University.

This study was supported by a Grant-in-Aid for Research Fellow from the Japan Society for the Promotion of Science (15J04405).

Hawaii Island Inquiries about the research

Dr Harriet Parsons
660 North A’Ohoku Place
Hilo, Hawaii, 96720


 – 2017/07/18