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From time to time the JCMT is closed due to major maintenance work. The next scheduled closure of the JCMT will occur from April 30th 2018 to mid May 2018. During this time the Gore-Tex membrane windblind will be removed to provide access to the Secondary Mirror Unit for maintenance work. As the telescope will be unavailable for science during this time the SCUBA-2 Gas Handling System will also be worked on. SCUBA-2 will be warm during this period and should back to operational temperature/available for science use by the end of May.
The staff at EAO would like to announce that we are planning an approximately month-long observing campaign without our iconic Gore-Tex membrane windblind.
The removal of the membrane is due to the high demand for sub-mm polarimetry. Currently the instrument POL-2 is commissioned and working beautifully at 0.85mm, with some fantastic science results. POL-2 science at 0.85 mm has been so successful that we are keen to see if operating without the membrane – which can limit the throughput and increase instrumental polarization – we can commission POL-2 at 0.45 mm.
Observing without the membrane is not our normal mode of operation and the telescope will have additional operational limitations during this time. The JCMT will not take daytime observations and the operational wind limits will be reduced.
We expect to remove the membrane early in December and thank the JCMT astronomical community for their support.
The migration of our OMP database system is now complete.
Principal Investigators/Co-Investigators on current JCMT programs (17B PI programs, Urgent queue programs, and the Large Programs) should again be able to retrieve recently-acquired data for their program from either the program’s OMP page or directly from the JCMT data archive at the CADC. As usual, the former method requires that the user’s OMP and CADC accounts are first linked (please see here for more details).
Any PIs/Co-Is that continue to encounter problems should consult their designated Friend of Project (FoP).
We are currently migrating our OMP database system, a process that is expected to take up to 4 weeks. During this period, any Principal Investigators/Co-Investigators on current JCMT programs (17B PI, Urgent queue projects, and the Large Programs) wishing to retrieve recently-acquired data for their projects should download it directly from the JCMT data archive at the CADC, rather than from the project’s OMP pages.
Update: This database migration process has now been completed (see above for further details).
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
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The Kavli Institute for Astronomy and Astrophysics (KIAA)
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James Clerk Maxwell Telescope
The East Asian Observatory is happy to invite PI observing proposals for semester 18A at JCMT. Proposal submission is via the JCMT proposal handling system, Hedwig. For full details, and for proposal submission please see
The 18A Call for Proposals closes on the 15th of September, 2017.
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 email@example.com if you have remaining questions.
The Greenland Telescope (GLT) is a novel project; taking a 12-meter radio antenna – prototype for the Atacama Large Millimeter/Submillimeter Array (ALMA) project from Chile, and relocating this telescope to Greenland.
By repurposing this telescope astronomers can take advantage of the near-ideal conditions of the Arctic to study the Universe at specific radio frequencies. Whilst the telescope is being commissioned the initial receiver that will be used at the GLT is being tested at the JCMT in Hawaii. Last week the alignment of the instrument was performed this morning using the Sun as a source – and at the JCMT the first astronomical source for this instrument!
The EAO Mid Term Review committee are meeting this week in Hilo to discuss the future of the JCMT. When the East Asian Observatory took over operation of the JCMT back in 2015 it was for an initial 5 years. Since that time we have had 5 semesters of great science. We have successfully completed three large programs (S2COSMOS, SCOPE, MALATANG). We have uncovered new star-forming events in the sub-mm. We have discovered stellar mass black holes. Our EAO regions have gained access to both Subaru and SMA. Recently we welcomed Vietnam as an observing partner in the JCMT. So much to celebrate!