CHIMPS: the 13^{13}CO/C18^{18}O (J=3-2) Heterodyne Inner Milky Way Plane Survey

We present the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| < 0.5 deg and 28 < l < 46 deg, with an angular resolution of 15 arcsec in 0.5 km/s velocity channels. The spectra have a median rms of $\sim$ 0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of $N_{\mathrm{H}_{2}} \sim 3 \times 10^{20}\,$cm$^{-2}$ and $N_{\mathrm{H}_{2}} \sim 4 \times 10^{21}\,$cm$^{-2}$ for $^{13}$CO and C$^{18}$O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J=3-2 transition of CO is $\gtrsim 10^{4}$ cm$^{-3}$ at temperatures of $\leq 20$ K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated emission maps for the region covered. Position-velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four arm model, there are some significant deviations

The JCMT Plane Survey: early results from the l = 30 degree field

We present early results from the JCMT Plane Survey (JPS), which has surveyed the northern inner Galactic plane between longitudes l=7 and l=63 degrees in the 850-{\mu}m continuum with SCUBA-2, as part of the James Clerk Maxwell Telescope Legacy Survey programme. Data from the l=30 degree survey region, which contains the massive star-forming regions W43 and G29.96, are analysed after approximately 40% of the observations had been completed. The pixel-to-pixel noise is found to be 19 mJy/beam, after a smooth over the beam area, and the projected equivalent noise levels in the final survey are expected to be around 10 mJy/beam. An initial extraction of compact sources was performed using the FellWalker method resulting in the detection of 1029 sources above a 5-{\sigma} surface-brightness threshold. The completeness limits in these data are estimated to be around 0.2 Jy/beam (peak flux density) and 0.8 Jy (integrated flux density) and are therefore probably already dominated by source confusion in this relatively crowded section of the survey. The flux densities of extracted compact sources are consistent with those of matching detections in the shallower ATLASGAL survey. We analyse the virial and evolutionary state of the detected clumps in the W43 star-forming complex and find that they appear younger than the Galactic-plane average

An unbiased survey of 500 nearby stars for debris disks: A JCMT legacy program

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 the Infrared 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, including Herschel, ALMA, and JWST, 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)

A study of Galactic Plane Planck Galactic cold clumps observed by SCOPE and the JCMT Plane Survey

We have investigated the physical properties of Planck Galactic Cold Clumps (PGCCs) located in the Galactic Plane, using the JCMT Plane Survey (JPS) and the SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE) survey. By utilizing a suite of molecular-line surveys, velocities, and distances were assigned to the compact sources within the PGCCs, placing them in a Galactic context. The properties of these compact sources show no large-scale variations with Galactic environment. Investigating the star-forming content of the sample, we find that the luminosity-to-mass ratio (L/M) is an order of magnitude lower than in other Galactic studies, indicating that these objects are hosting lower levels of star formation. Finally, by comparing ATLASGAL sources that are associated or are not associated with PGCCs, we find that those associated with PGCCs are typically colder, denser, and have a lower L/M ratio, hinting that PGCCs are a distinct population of Galactic Plane sources

CHIMPS: the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey

This is the final version of the article. Available from OUP] via the DOI in this record.We present the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| ≤ 0 ∘..∘5 and 28deg≲l≲46deg28deg≲l≲46deg, with an angular resolution of 15 arcsec in 0.5 km s−1 velocity channels. The spectra have a median rms of ∼0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of NH2 ∼ 3 × 1020 cm−2 and NH2 ∼ 4 × 1021 cm−2 for 13CO and C18O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J = 3 → 2 transition of CO is ≳104 cm−3 at temperatures of ≤20 K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated-emission maps for the region covered. Position–velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four-arm model, there are some significant deviations.AJR would like to thank David Berry and especially Malcolm Currie for their assistance with ORAC-DR and other Starlink applications. AJR also acknowledges the support of an STFC-funded studentship, and the support of the Royal Astronomical Society for overseas travel to present CHIMPS data. The James Clerk Maxwell Telescope has historically been operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the National Research Council of Canada and the Netherlands Organisation for Scientific Research. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. This research made use of the NASA Astrophysical Data System. This research has also made use of the SIMBAD data base, operated at CDS, Strasbourg, France. This research made use of ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013). This research also made use of APLPY, an open-source plotting package for PYTHON hosted at http://aplpy.github.com. MZ acknowledges support from the China Ministry of Science and Technology under the State Key Development Program for Basic Research (2012CB821800