arXiv subjects

C. R. Kerton

Publications and source records attributed to C. R. Kerton.

24 records · Page 2Linked to original sources

arXiv2001

A Fast Technique for the Creation of Large-Scale High-Resolution IRAS (HIRES) Beam-matched Images

HIRES processing provides a significant improvement in both resolution and image quality over previous IRAS image products, but the characteristics of the HIRES beam make accurate comparisons between the various IRAS bandpasses and between HIRES data and data at other wavelengths non-trivial. We present a new, fast technique for the construction of HIRES beam-matched images that is especially well suited for the creation of large-scale (several square degrees) ratio maps. Other techniques for the construction of ratio maps are discussed and compared with the new algorithm. Examples of the large-scale ratio maps that can be constructed using this new technique are presented. The algorithm's application to the construction of multiwavelength difference images and multi-colour images is also demonstrated.

astro-ph↗

arXiv2000

The HII Region KR 140: Spontaneous Formation of a High Mass Star

We have used a multiwavelength data set from the Canadian Galactic Plane Survey (CGPS) to study the Galactic HII region KR 140, both on the scale of the nebula itself and in the context of the star forming activity in the nearby W3/W4/W5 complex of molecular clouds and HII regions. From both radio and infrared data we have found a covering factor of about 0.5 for KR 140 and we interpret the nebula as a bowl-shaped region viewed close to face on. Extinction measurements place the region on the near side of its parent molecular cloud. The nebula is kept ionized by one O8.5 V(e) star, VES 735, which is less than a few million years old. CO data show that VES 735 has disrupted much of the original molecular cloud for which the estimated mass and density are about 5000 $M_{\odot}$ and 100 cm$^{-3}$, respectively. KR 140 is isolated from the nearest star forming activity, in W3. Our data suggest that KR 140 is an example of spontaneous (i.e., non-triggered) formation of, unusually, a high mass star.

astro-ph↗

arXiv1999

A Mid-Infrared Galaxy Atlas (MIGA)

A mid-infrared atlas of part of the Galactic plane ($75^\circ < l < 148^\circ, b = \pm6^\circ$) has been constructed using HIRES processed infrared data to provide a mid-infrared data set for the Canadian Galactic Plane Survey (CGPS). The addition of this data set to the CGPS will enable the study of the emission from the smallest components of interstellar dust at an angular resolution comparable to that of the radio, millimetre, and far-infrared data in the CGPS. The Mid-Infrared Galaxy Atlas (MIGA) is a mid-infrared (12 $μ$m and 25 $μ$m) counterpart to the far-infrared IRAS Galaxy Atlas (IGA), and consists of resolution enhanced ($\sim 0.5'$ resolution) HIRES images along with ancillary maps. This paper describes the processing and characteristics of the atlas, the cross-beam simulation technique used to obtain high-resolution ratio maps, and future plans to extend both the IGA and MIGA.

astro-ph↗

arXiv1999

A Mid-Infrared HIRES Atlas of the Galactic Plane

A mid-infrared atlas of the Galactic Plane (MIGA) has been constructed to provide a mid-infrared data set for the Canadian Galactic Plane Survey, an international project to map all of the major components of the interstellar medium of the Milky Way at a common resolution of approximately 1'. The atlas is based on HIRES processing of IRAS 12 and 25 micron data. Details of the MIGA production and applications of the atlas are discussed and illustrated.

astro-ph↗

arXiv1999

Multiwavelength Studies of Interstellar Dust Using WIRE and MIGA

Studies of interstellar dust using the recently completed Mid-Infrared Galaxy Atlas (MIGA) and the soon to be launched Wide-Field Infrared Explorer (WIRE) satellite are summarized. Projects include looking at the distribution of dust around HII regions, the study of dust at the interfaces of HII regions and molecular clouds, and understanding the colour variations seen in cirrus clouds.

astro-ph↗

arXiv1999

Classification of O Stars in the Yellow-Green: The Exciting Star VES 735

Acquiring data for spectral classification of heavily reddened stars using traditional criteria in the blue-violet region of the spectrum can be prohibitively time consuming using small to medium sized telescopes. One such star is the Vatican Observatory emission-line star VES 735, which we have found excites the HII region KR140. In order to classify VES 735, we have constructed an atlas of stellar spectra of O stars in the yellow-green (4800 - 5420 A). We calibrate spectral type versus the line ratio HeI 4922:HeII 5411, showing that this ratio should be useful for the classification of heavily reddened O stars associated with HII regions. Application to VES 735 shows that the spectral type is O8.5. The absolute magnitude suggests luminosity class V. Comparison of the rateof emission of ionizing photons and the bolometric luminosity of VES 735, inferred from radio and infrared measurements of the KR 140 region, to recent stellar models gives consistent evidence for a main sequence star of mass 25 M_sun and age less than a few million years with a covering factor 0.4 - 0.5 by the nebular material. Spectra taken in the red (6500 - 6700 A) show that the stellar H-alpha emission is double-peaked about the systemic velocity and slightly variable. H-beta is in absorption, so that the emission-line classification is ``(e)''. However, unlike the case of the more well known O(e) star Zeta Oph, the emission from VES 735 appears to be long-lived rather than episodic.

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