2MASS near-infrared photometry of symbiotic stars     

J. P. Phillips 《Monthly notices of the Royal Astronomical Society》2007,376(3):1120-1132

We present Two Micron All Sky Survey photometry for 216 symbiotic and possible symbiotic stars. This represents the most comprehensive near-infrared photometry for these sources which has been published to date. The results are used to define the statistics of S- and D-type stars; to investigate the photometric properties of Magellanic S-type symbiotics; and to define the possible evolution of D-type symbiotics within the J − H / H − K _S colour plane. It appears that the colours of D-type symbiotics are consistent with differing mass-loss rates d M /d t , provided that the grains have a silicate-like composition, and maximum temperatures of the order of ∼800 K.  相似文献   

Density gradients in Galactic ultra-compact H ii regions     

J. P. Phillips 《Monthly notices of the Royal Astronomical Society》2007,380(1):369-373

We have used recent radiative transfer solutions for cavity-centred shells to investigate the prevalence of density gradients in Galactic ultra-compact H  ii regions. We find that an analysis of 5 and 1.4 GHz data, taken from the recent compilation of Giveon et al., implies that ∼76 per cent of sources may have appreciable density gradients. It would also seem that the central cavities of these sources must be relatively small, with radii no greater than ∼20 per cent of those of the outer shells. The remainder of these sources are presumably homogenous, have much larger cavities, or possess reverse density gradients (densities which increase with increasing radius). A good fraction of the H  ii regions also appear to have high brightness temperatures, implying mean electron temperatures  〈 T _e〉  of the order of  ≈1.3 × 10⁴ K  . This value is higher than has been determined for other such sources.  相似文献   

Glacial modification of granite tors in the Cairngorms,Scotland     

A. M. Hall  W. M. Phillips 《第四纪科学杂志》2006,21(8):811-830

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Vague cognitive regions in geography and geographic information science     

Daniel R. Montello  Alinda Friedman  Daniel W. Phillips 《International journal of geographical information science》2014,28(9):1802-1820

Cognitive regions are regions in the mind, reflecting informal ways individuals and cultural groups organize their understanding of earth landscapes. Cognitive region boundaries are typically substantially vague and their membership functions are substantially variable – the transition from outside to inside the region is imprecise or vague, and different places within the region are not equally strong or clear as exemplars of the region. Methods for assessing and cartographically depicting cognitive regions, as with other vague geographic regions, have traditionally implied an inappropriate level of boundary sharpness and membership uniformity, such as when boundaries are mapped as precise lines. Research in recent decades has explored methods for assessing and depicting boundary vagueness and membership variability, either within or across individuals, but has still assumed homogeneity and regularity in the vagueness and variability. In this article, we present two studies that assess the cognitive regions of ‘Northern’ and ‘Southern’ California, and, for comparison, ‘Northern’ and ‘Southern’ Alberta. The first study uses a standard boundary-drawing task; the second uses a novel task in which participants rate cells of a high-resolution grid laid over an outline map. This technique allows us to assess and depict vagueness and nonuniformity that is heterogeneous and irregular across different areas. Differences in the conceptualization of ‘Northern’ and ‘Southern’ regions in California, as compared to those in Alberta, point to thematic influences on cognitive regions in California but not in Alberta. As is often true with cognitive regions, Northern and Southern California are about attitude, not just latitude.  相似文献   

Hydrofracturing in response to the development of an overpressurised subglacial meltwater system during drumlin formation: an example from Anglesey,NW Wales     

Emrys Phillips  Leanne Hughes 《Proceedings of the Geologists' Association. Geologists' Association》2014

This paper presents the results of a detailed study of a complex hydrofracture system and host diamictons exposed within a longitudinal section through an elongate drumlin located to the west of Cemlyn Bay, Anglesey, NW Wales. This complex, laterally extensive sand, silt and clay filled hydrofracture system was active over a prolonged period and is thought to have developed beneath the Late Devensian (Weichselian) Irish Sea Ice Stream as it overrode this part of NW Anglesey. The sediment-fill to the hydrofracture system is deformed with kinematic indicators (folds, thrusts, augen) recording a SW-directed sense of shear, consistent with the regional ice flow direction across this part of the island. The lack of any geomorphological evidence for active retreat of the Irish Sea ice across Anglesey has led to the conclusion that hydrofracturing at the Cemlyn Bay site occurred within the bed of the Irish Sea Ice Stream whilst this relatively faster flowing corridor of ice was actively overriding the island. Shear imposed by the overriding ice led to the development of a subglacial shear zone which facilitated the propagation of the hydrofracture system with the laterally extensive feeder sills occurring parallel to Y-type Riedel shears. Although a subglacial setting beneath the active Irish Sea Ice Stream can be argued for the Cemlyn Bay hydrofracture system, its relationship to the formation of the ‘host’ drumlin remains uncertain. However, evidence presented here suggests that hydrofracturing may have occurred during the later stages or post landform development in response to the migration of overpressurised meltwater within the bed of the Irish Sea ice; possibly accompanying the local thinning and shutdown of the Irish Sea Ice Stream on Anglesey.  相似文献   

The low-excitation structures of planetary nebulae     

J. P. Phillips  L. Cuesta  V. Ortega 《Monthly notices of the Royal Astronomical Society》2001,322(4):866-876

The low excitation properties of the planetary nebula (PN) NGC 6720 are known to be unusual, and to imply large ring/core emission ratios. We point out that such characteristics are by no means confined to this source alone, and that high ratios may occur in a large fraction of elliptical and circular PNe. Such trends may arise because of the presence of thin low-excitation emission sheets 'wrapped' within and around the primary outflows. The widths of such shells are required to be exceedingly small, and may (for certain cases) be of order ≪10⁻² pc. Such a mechanism appears capable of explaining most of the observed emission properties, and may arise through shock interaction between differing envelopes. Alternative explanations in terms of bipolar or cylindrical outflows are shown to be implausible.  相似文献   

An intercomparison of two rawinsonde systems     

G.A. McBean  D.J. Phillips  J.R. Mathieson 《大气与海洋》2013,51(1):42-51

Abstract

An intercomparison of the Väisälä MicroCora system used in the Automated Shipboard Aerological Program (ASAP) and the Atmospheric Environment Service upper‐air system (GMD/ADRES) was conducted in May‐June 1983. Thirty‐three paired ascents were made. The ASAP system dry‐bulb temperatures averaged 0.3°C warmer. For the lowest 100 mb, the dew‐point temperature difference (ASAP ‐ GMD/ADRES) was near ‐1°C whereas for the 780–500 mb layer, the difference was 1°C. The wind component mean differences averaged were small but with a 4 m s^?1 standard deviation.  相似文献   

Molecular line mapping of the giant molecular cloud associated with RCW 106 – I. ¹³CO     

I. Bains  T. Wong  M. Cunningham  P. Sparks  D. Brisbin  P. Calisse  J. T. Dempsey  G. Deragopian  S. Ellingsen  B. Fulton  F. Herpin  P. Jones  Y. Kouba  C. Kramer  E. F. Ladd  S. N. Longmore  J. McEvoy  M. Maller  V. Minier  B. Mookerjea  C. Phillips  C. R. Purcell  A. Walsh  M. A. Voronkov  M. G. Burton 《Monthly notices of the Royal Astronomical Society》2006,367(4):1609-1628

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A Molecular Filament Threaded by Helical Magnetic Fields?     

P. Hily-Blant  E. Falgarone  G. Pineau des Forêts  T. G. Phillips 《Astrophysics and Space Science》2004,292(1-4):285-289

We present a multitransition study in the ¹³CO(1-0), ¹²CO(2-1), ¹²CO(3-2) and ¹²CO(4-3) lines of a parsec scale elongated structure connected to a low-mass dense core. Densities larger than n _{H 2} = 10⁴ cm^?3 are inferred in the central regions of this structure, supporting the proposition that it is a genuine filament denser than its environment. The sharp observed drop of the ¹²CO and ¹³CO emissions requires a power law density fall-off steeper than r ^?1 although a single density law cannot reproduce the spatial shift of 0.1 pc between the ¹³CO and ¹²CO drops. Our results support the previous proposition that this elongated structure is a filament threaded by helical magnetic fields, channeling the gas inflow onto the dense core.  相似文献   

Stokes imaging, Doppler mapping and Roche tomography of the AM Herculis system V834 Cen   总被引：1，自引：0，他引：1  

Stephen B. Potter  E. Romero-Colmenero  C. A. Watson  D. A. H. Buckley  A. Phillips 《Monthly notices of the Royal Astronomical Society》2004,348(1):316-324

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