We present the scientific motivation and observing plan for an upcoming detection survey for debris disks using the James Clerk Maxwell Telescope. The SCUBA‐2 Unbiased Nearby Stars (SUNS) survey will ...observe 500 nearby main‐sequence and subgiant stars (100 of each of the A, F, G, K, and M spectral classes) to the 850 μm extragalactic confusion limit to search for evidence of submillimeter excess, an indication of circumstellar material. The survey distance boundaries are 8.6, 16.5, 22, 25, and 45 pc for M, K, G, F, and A stars, respectively, and all targets lie between the declinations of −40° to 80°. In this survey, no star will be rejected based on its inherent properties: binarity, presence of planetary companions, spectral type, or age. The survey will commence in late 2007 and will be executed over 390 hr, reaching 90% completion within 2 years. This will be the first unbiased survey for debris disks since theInfrared Astronomical Satellite. We expect to detect ∼125 debris disks, including ∼50 cold disks not detectable in current shorter wavelength surveys. To fully exploit the order of magnitude increase in debris disks detected in the submillimeter, a substantial amount of complementary data will be required, especially at shorter wavelengths, to constrain the temperatures and masses of discovered disks. High‐resolution studies will likely be required to resolve many of the disks. Therefore, these systems will be the focus of future observational studies using a variety of observatories, includingHerschel, ALMA, andJWST, to characterize their physical properties. For nondetected systems, this survey will set constraints (upper limits) on the amount of circumstellar dust, of typically 200 times the Kuiper Belt mass, but as low as 10 times the Kuiper Belt mass for the nearest stars in the sample (≈2 pc).
The James Clerk Maxwell Telescope (JCMT) has been the world's most successful single dish telescope at submillimetre wavelengths since it began operations in 1987. From the pioneering days of ...single-element photometers and mixers, through the first modest imaging arrays, leading to the state-of-the-art widefield camera SCUBA-2 and the spectrometer array HARP, the JCMT has been associated with a number of major scientific discoveries. Famous for the discovery of "SCUBA" galaxies, which are responsible for a large fraction of the far-infrared background, to the first images of huge discs of cool debris around nearby stars, possibly giving us clues to the evolution of planetary systems, the JCMT has pushed the sensitivity limits more than any other facility in this most difficult of wavebands in which to observe. Now approaching the 30th anniversary of the first observations the telescope continues to carry out unique and innovative science. In this review article we look back on just some of the scientific highlights from the past 30 years.
We report 850 \(\mu\)m continuum polarization observations toward the filamentary high-mass star-forming region NGC 2264, taken as part of the B-fields In STar forming Regions Observations (BISTRO) ...large program on the James Clerk Maxwell Telescope (JCMT). These data reveal a well-structured non-uniform magnetic field in the NGC 2264C and 2264D regions with a prevailing orientation around 30 deg from north to east. Field strengths estimates and a virial analysis for the major clumps indicate that NGC 2264C is globally dominated by gravity while in 2264D magnetic, gravitational, and kinetic energies are roughly balanced. We present an analysis scheme that utilizes the locally resolved magnetic field structures, together with the locally measured gravitational vector field and the extracted filamentary network. From this, we infer statistical trends showing that this network consists of two main groups of filaments oriented approximately perpendicular to one another. Additionally, gravity shows one dominating converging direction that is roughly perpendicular to one of the filament orientations, which is suggestive of mass accretion along this direction. Beyond these statistical trends, we identify two types of filaments. The type-I filament is perpendicular to the magnetic field with local gravity transitioning from parallel to perpendicular to the magnetic field from the outside to the filament ridge. The type-II filament is parallel to the magnetic field and local gravity. We interpret these two types of filaments as originating from the competition between radial collapsing, driven by filament self-gravity, and the longitudinal collapsing, driven by the region's global gravity.
In 2018, the Greenland Telescope (GLT) started scientific observation in Greenland. Since then, we have completed several significant improvements and added new capabilities to the telescope system. ...This paper presents a full review of the GLT system, a summary of our observation activities since 2018, the lessons learned from the operations in the Arctic regions, and the prospect of the telescope.
The Submillimetre Common User Bolometer Array 2 (SCUBA-2) is the James Clerk
Maxwell Telescope's continuum imager, operating simultaneously at 450 and
850~$\mu$m. SCUBA-2 was commissioned in ...2009--2011 and since that time, regular
observations of point-like standard sources have been performed whenever the
instrument is in use. Expanding the calibrator observation sample by an order
of magnitude compared to previous work, in this paper we derive updated opacity
relations at each wavelength for a new atmospheric-extinction correction,
analyze the Flux-Conversion Factors (FCFs) used to convert instrumental units
to physical flux units as a function of date and observation time, present
information on the beam profiles for each wavelength, and update
secondary-calibrator source fluxes. Between 07:00 and 17:00 UTC, the portion of
the night that is most stable to temperature gradients that cause dish
deformation, the total-flux uncertainty and the peak-flux uncertainty measured
at 450~$\mu$m are found to be 14\% and 17\%, respectively. Measured at
850~$\mu$m, the total-flux and peak-flux uncertainties are 6\%, and 7\%,
respectively. The analysis presented in this work is applicable to all SCUBA-2
projects observed since 2011.
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