arXiv subjects

S. Kimeswenger

Publications and source records attributed to S. Kimeswenger.

59 records · Page 4Linked to original sources

arXiv2000

New identification of the near infrared Source in the "born-again" planetary nebula A58 (=V605 Aql)

The central dust knot V605 Aql (= Nova Aql 1919) in the planetary nebula A58 is the result of a late-helium flash. Previous near infrared (NIR) measurements yield very bright fluxes. This exceeds model predictions, based on other wavelengths and estimates of the visual extinction within the object, by a factor of 100. Using NIR imaging by the DENIS instrument, we found that the source was misidentified in previous (single channel photometer) observations. We present the NIR flux of A58 and identify an unrelated stellar field source, which in fact represents the NIR source attributed to A58, according to the literature. The new identification is consistent with model predictions for the source. An accurate astrometry for the core of A58 is also provided.

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arXiv1999

ISOGAL-DENIS detection of red giants with weak mass loss in the Galactic Bulge

The ISOGAL project is a survey of the stellar populations, structure, and recent star formation history of the inner disk and bulge of the Galaxy. ISOGAL combines 15 and 7micron ISOCAM observations with DENIS IJKs data to determine the nature of a source and the interstellar extinction. In this paper we report an ISOGAL study of a small field in the inner Galactic Bulge (l=0deg, b=1.0deg, area=0.035 sq. deg) as a prototype of the larger area ISOGAL survey of the inner Galaxy. The five wavelengths of ISOGAL+DENIS, together with the relatively low and constant extinction in front of this specific field, allow reliable determination of the nature of the sources. The primary scientific result of this paper is evidence that the most numerous class of ISOGAL 15micron sources are Red Giants in the Galactic bulge and central disk, with luminosities just above or close to the RGB tip and weak mass-loss rates. They form loose sequences in the magnitude-colour diagrams [15]/Ks-[15] and [15]/[7]-[15]. Their large excesses at 15micron with respect to 2micron and 7micron is due to circumstellar dust produced by mass-loss at low rates. These ISOGAL results are the first systematic evidence and study of dust emission at this early stage (''Intermediate'' AGB), before the onset of the large mass-loss phase. It is thus well established that efficient dust formation is already associated with such low mass-loss rates during this early phase.

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arXiv1999

First DENIS I-band extragalactic catalog

This paper presents the first I-band photometric catalog of the brightest galaxies extracted from the Deep Near Infrared Survey of the Southern Sky (DENIS) An automatic galaxy recognition program has been developed to build this provisional catalog. The method is based on a discriminating analysis. The most discriminant parameter to separate galaxies from stars is proved to be the peak intensity of an object divided by its array. Its efficiency is better than 99%. The nominal accuracy for galaxy coordinates calculated with the Guide Star Catalog is about 6 arcseconds. The cross-identification with galaxies available in the Lyon-Meudon Extragalactic DAtabase (LEDA) allows a calibraton of the I-band photometry with the sample of Mathewson et Al. Thus, the catalog contains total I-band magnitude, isophotal diameter, axis ratio, position angle and a rough estimate of the morphological type code for 20260 galaxies. The internal completeness of this catalog reaches magnitude $I_{lim}=14.5$, with a photometric accuracy of $\sim 0.18m$. 25% of the Southern sky has been processed in this study. This quick look analysis allows us to start a radio and spectrographic follow-up long before the end of the survey.

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arXiv1998

New Young Stellar Object candidates in the Chamaeleon I molecular cloud discovered by DENIS

This paper presents an analysis of the nature of point sources discovered by DENIS in an area of 1.5 x 3 degrees around the Chamaeleon I molecular cloud. Most of the 30000 objects detected in the J band are background stars that were previously used to derive an accurate extinction map of the full area (Cambresy et al., 1997) using star count method. In the present work, we investigate the young stellar population of the cloud using the IJK photometric DENIS data. The whole sample of 126 already known YSOs, which are mainly T Tauri stars, are identified in the DENIS catalogue. Besides, we propose 54 sources as new candidates of YSOs. These new faint objects are selected according to their extremely red near infrared colour, that cannot be explained only by the reddening of the cloud. Moreover they are concentrated near to the most obscured areas of the cloud. Although spectroscopic confirmation is badly requested, they are interpreted as probable classical T Tauri stars that have escaped previous spectroscopic, IRAS or X-ray observations and pertaining to the low-end of the luminosity function. Assuming that they are reliable YSOs with massive accretion disks, and using theoretical pre-main-sequence tracks we estimate the age of this sample to be ranging from 5 10^5 to 4 10^6 years, an elapse of time that spans the range between the end of the star formation in the cloud and the maximum life time of the circumstellar disk.

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arXiv1997

Extinction map of the Chamaeleon I molecular cloud with DENIS star counts

Massive, large scale star counts in the J band provided by the Deep Near Infrared Survey of the Southern Sky (DENIS) are used for the first time to draw out an extinction map of the Chamaeleon I dark cloud. We derived a 2 arcminutes resolution map of the cloud from J star counts within an area of 1.5 x 3 degres around the centre of the cloud using an adaptive grid method and applying a wavelet decomposition. A comparison of our extinction map with the cold contribution of the IRAS 100 microns emission shows an almost perfect matching. It is shown that J star counts supersede optical counts on Schmidt plate where Av > 4.

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