Publications of the Astronomical Society of the Pacific

Matthews, Brenda C.; Greaves, Jane S.; Holland, Wayne S.; Wyatt, Mark C.; Barlow, Michael J.; Bastien, Pierre; Beichman, Chas. A.; Biggs, Andrew; Butner, Harold M.; Dent, William R. F.; Di Francesco, James; Dominik, Carsten; Fissel, Laura; Friberg, Per; Gibb, A. G.; Halpern, Mark; Ivison, R. J.; Jayawardhana, Ray; Jenness, Tim; Johnstone, Doug; Kavelaars, J. J.; Marshall, Jonathon L.; Phillips, Neil; Schieven, Gerald; Snellen, Ignas A. G.; Walker, Helen J.; Ward‐Thompson, Derek; Weferling, Bernd; White, Glenn J.; Yates, Jeremy; Zhu, Ming; Craigon, Alison

doi: 10.1086/521318pmid: N/A

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).

Ward‐Thompson, D.; Di Francesco, J.; Hatchell, J.; Hogerheijde, M. R.; Nutter, D.; Bastien, P.; Basu, S.; Bonnell, I.; Bowey, J.; Brunt, C.; Buckle, J.; Butner, H.; Cavanagh, B.; Chrysostomou, A.; Curtis, E.; Davis, C. J.; Dent, W. R. F.; van Dishoeck, E.; Edmunds, M. G.; Fich, M.; Fiege, J.; Fissel, L.; Friberg, P.; Friesen, R.; Frieswijk, W.; Fuller, G. A.; Gosling, A.; Graves, S.; Greaves, J. S.; Helmich, F.; Hills, R. E.; Holland, W. S.; Houde, M.; Jayawardhana, R.; Johnstone, D.; Joncas, G.; Kirk, H.; Kirk, J. M.; Knee, L. B. G.; Matthews, B.; Matthews, H.; Matzner, C.; Moriarty‐Schieven, G. H.; Naylor, D.; Padman, R.; Plume, R.; Rawlings, J. M. C.; Redman, R. O.; Reid, M.; Richer, J. S.; Shipman, R.; Simpson, R. J.; Spaans, M.; Stamatellos, D.; Tsamis, Y. G.; Viti, S.; Weferling, B.; White, G. J.; Whitworth, A. P.; Wouterloot, J.; Yates, J.; Zhu, M.

doi: 10.1086/521277pmid: N/A

This paper describes a James Clerk Maxwell Telescope (JCMT) legacy survey that has been awarded roughly 500 hr of observing time to be carried out from 2007 to 2009. In this survey, we will map with SCUBA‐2 (Submillimetre Common‐User Bolometer Array 2) almost all of the well‐known low‐mass and intermediate‐mass star‐forming regions within 0.5 kpc that are accessible from the JCMT. Most of these locations are associated with the Gould Belt. From these observations, we will produce a flux‐limited snapshot of star formation near the Sun, providing a legacy of images, as well as point‐source and extended‐source catalogs, over almost 700 deg2 of sky. The resulting images will yield the first catalog of prestellar and protostellar sources selected by submillimeter continuum emission, and should increase the number of known sources by more than an order of magnitude. We will also obtain with the array receiver HARP (Heterodyne Array Receiver Program) CO maps, in three CO isotopologues, of a large typical sample of prestellar and protostellar sources. We will then map the brightest hundred sources with the SCUBA‐2 polarimeter (POL‐2), producing the first statistically significant set of polarization maps in the submillimeter. The images and source catalogs will be a powerful reference set for astronomers, providing a detailed legacy archive for future telescopes, including ALMA, Herschel, and JWST.

Houde, Martin; Vaillancourt, John E.

doi: 10.1086/521109pmid: N/A

We address the question of astronomical image processing from data obtained with array detectors. We define and analyze the cases of evenly, regularly, and irregularly sampled maps for idealized (i.e., infinite) and realistic (i.e., finite) detectors. We concentrate on the effect of interpolation on the maps and the choice of the kernel used to accomplish this task. We show how the normalization intrinsic to the interpolation process must be carefully accounted for when dealing with irregularly sampled grids. We also analyze the effect of missing or dead pixels in the array and their consequences for the Nyquist sampling criterion.

Eaton, Joel A.; Williamson, Michael H.

doi: 10.1086/521231pmid: N/A

This paper discusses data reduction for an echelle spectrograph we have developed for an automatic telescope at Tennessee State University and are using to monitor radial velocities and line profiles of cool giant and supergiant stars. Although our approach to data reduction is rather conventional, we discuss flat‐fielding and extraction of velocities in ways that should be of general interest, establish a transformation to the IAU radial velocity system (+0.35 ± 0.09 km s−1), and determine the external precision for measured velocities (0.10–0.11 km s−1). Also, we present results of the first 2–3 years of monitoring radial velocities in about 120 cool giants and compare those results with the level of variability found with photometry. These new data confirm the widely held understanding that K and M giants are all radial velocity variables at the level of 0.1 km s−1.

Comparato, M.; Becciani, U.; Costa, A.; Larsson, B.; Garilli, B.; Gheller, C.; Taylor, J.

doi: 10.1086/521375pmid: N/A

In this paper, we show how advanced visualization tools can help the researcher in investigating and extracting information from data. The focus is on VisIVO, a novel open‐source graphics application that blends high‐performance multidimensional visualization techniques and up‐to‐date technologies to cooperate with other applications and to access remote, distributed data archives. VisIVO supports the standards defined by the International Virtual Observatory Alliance in order to make it interoperable with VO data repositories. The paper describes the basic technical details and features of the software, and it dedicates a large section to show how VisIVO can be used in several scientific cases.

Allen, Ronald J.

doi: 10.1086/521276pmid: N/A

The accuracy requirements on station‐keeping for constellations of free‐flying collectors that are coupled as (future) imaging arrays in space for astrophysics applications are examined. The basic imaging element of these arrays is the two‐element interferometer. Accurate knowledge of two quantities is required: the “projected baseline length,” which is the distance between the two interferometer elements projected on the plane transverse to the line of sight to the target, and the “optical path difference,” which is the difference in the distances from that transverse plane to the beam combiner. Rules of thumb are determined for the typical accuracy required on these parameters. The requirement on the projected baseline length is a “knowledge” requirement and depends on the angular size of the targets of interest. It is generally at a level of half a meter for typical stellar targets, decreasing to perhaps a few centimeters only for the widest attainable fields of view. The requirement on the optical path difference is a “control” requirement and is much tighter, depending on the bandwidth of the signal. It is at a level of half a wavelength for narrow (few percent) signal bands, decreasing to ≈0.2 λ for the broadest bandwidths expected to be useful. Translation of these requirements into engineering requirements on station‐keeping accuracy depends on the specific details of the collector constellation geometry. Several examples are provided to guide future application of the criteria presented here. Some implications for the design of such collector constellations and for the methods used to transform the information acquired into images are discussed.

Pepper, Joshua; Pogge, Richard W.; DePoy, D. L.; Marshall, J. L.; Stanek, K. Z.; Stutz, Amelia M.; Poindexter, Shawn; Siverd, Robert; O’Brien, Thomas P.; Trueblood, Mark; Trueblood, Patricia

doi: 10.1086/521836pmid: N/A

The Kilodegree Extremely Little Telescope (KELT) project is a survey for planetary transits of bright stars. It consists of a small‐aperture, wide‐field automated telescope located at Winer Observatory near Sonoita, Arizona. The telescope surveys a set of 26° × 26° fields that together cover about 25% of the northern sky, and targets stars in the range of 8<V<10 mag, searching for transits by close‐in Jupiters. This paper describes the system hardware and software and discusses the quality of the observations. We show that KELT is able to achieve the necessary photometric precision to detect planetary transits around solar‐type main‐sequence stars.

Lee, Janice C.

doi: 10.1086/521376pmid: N/A