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J/A+A/478/755       Variable stars in Cen A                  (de Jong+, 2008)

Ground-based variability surveys towards Centaurus A: worthwhile or not? de Jong J.T.A., Kuijken K.H., Heraudeau P. <Astron. Astrophys. 478, 755 (2008)> =2008A&A...478..755D
ADC_Keywords: Galaxies, nearby ; Stars, variable Keywords: galaxies: individual: Centaurus A - galaxies: stellar content - stars: variables: general - gravitational lensing Abstract: Difference imaging has proven to be a powerful technique for detecting and monitoring the variability of unresolved stellar sources in M 31. Using this technique in surveys of galaxies outside the Local Group could have many interesting applications. The goal of this paper is to test difference imaging photometry on Centaurus A, the nearest giant elliptical galaxy, at a distance of 4Mpc. We obtained deep photometric data with the Wide Field Imager at the ESO/MPG 2.2m at La Silla spread over almost two months. Applying the difference imaging photometry package DIFIMPHOT, we produced high-quality difference images and detected variable sources. The sensitivity of the current observational setup was determined through artificial residual tests. In the resulting high-quality difference images, we detect 271 variable stars. We find a difference flux detection limit corresponding to mR~=24.5. Based on a simple model of the halo of Centaurus A, we estimate that a ground-based microlensing survey would detect in the order of 4 microlensing events per year due to lenses in the halo. Conclusions: Difference imaging photometry works very well at the distance of Centaurus A and promises to be a useful tool for detecting and studying variable stars in galaxies outside the local group. For microlensing surveys, a higher sensitivity is needed than achieved here, which would be possible with a large ground-based telescope or space observatory with wide-field imaging capabilities. Description: Basic data for 271 variable stars detected in Centaurus A. For all variables, an identifier, RA and Dec (J2000.0), and a classification is given. For a subset of 29 variables a period is provided as well; for the other variables a robust period determination was not possible due to the intrinsic nature of the object or due to the limited timespan of the observations. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 35 271 Variable stars in Centaurus A
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [CAVS] 6- 8 I3 --- CAVS CAVS number 10- 17 F8.4 deg RAdeg Right ascension in decimal degrees (J2000) 19- 26 F8.4 deg DEdeg Declination in decimal degrees (J2000) 28- 31 F4.1 d Per ? Period 33- 35 A3 --- VType Type of variation: V* = variable star, No* = Nova variable
Acknowledgements: Jelte de Jong, mailjelte(at)
(End) Jelte de Jong [MPIA], Patricia Vannier [CDS] 10-Dec-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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