Uncertainties in phase shifts and amplitude ratios: Theory and practice
- Author(s)
- Michel Breger
- Abstract
Multicolor data of pulsating variables yield information on the amplitude ratios and phase shifts between the different passbands. This is a powerful tool for mode identifications of radial and nonradial pulsators. The identifications rely on relatively small effects, so that the uncertainties due to measurement errors need to be known precisely.
We present the formulae which allow the calculation of the statistical uncertainties from the residuals between the measurements and the least-squares fit of sinusoids to the light curves. Since it has been often presumed that the real uncertainties of the amplitudes and phases are greater than calculated from statistics, we have compared the theoretical scatter with the observed scatter. Nine pulsation modes of the ? Scuti variable 44 Tau, extensively observed for five observing seasons, were chosen. The observed and predicted scatter of 86 pairs of amplitude ratios and phase shifts were compared.
We find that the observed and predicted scatter are very similar: the histograms of the observed scatter in the amplitude ratios and phase shifts match the normal distribution predicted from the formulae. The excellent agreement might be a consequence of the fact that most systematic observational and computational (caused by multiperiodicity) errors tend to cancel out when the measurements at the different passbands are compared.
- Organisation(s)
- Department of Astrophysics
- Journal
- Communications in Asteroseismology
- Volume
- 156
- Pages
- 6-14
- No. of pages
- 9
- ISSN
- 1021-2043
- Publication date
- 2008
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/85562440-8c6a-4fd2-a685-95a7666630d7