Close frequency pairs in Delta Scuti stars

The majority of the well-studied Delta Scuti stars show frequency pairs in the power spectra with frequency separations less than 0.06 c/d(0.7 microHz) as well as amplitude variability. We examine the interpretation in terms of separate excited stellar pulsation modes,single modes with variable amplitudes, and observational problems. The variable-phase technique, which examines the phase jumps near the times of minimum amplitude of an assumed single frequency, is applied to the extensive data of the star BI CMi, which shows some of the most extreme behavior. The following results are found for the 5 features in the power spectrum which could be explained as single modes with variable amplitudes or as double modes: for three features it can be shown that these are indeed pairs of separate pulsation modes beating with each other: at times of minimum amplitude the phase jumps are observed and both the observed amplitude and phase variations can be predicted correctly by assuming two separate modes of nearly equal frequencies. Artifacts caused by observational error,insufficient frequency resolution or variable amplitudes can be ruled out. A fourth pair has a probable origin in two excited modes, while a 5th case is inconclusive due to long time scales of variability and small amplitudes.The existence of close frequencies need to be taken into account in planning the lengths of earth-based as well as space campaigns so that sufficient frequency resolution is obtained. Possible reasons for the existence of close frequencies in Delta Scuti stars are considered.They include the dense frequency spacing caused by the presence of mixed modes, rotational splitting as well as near-coincidence of the frequencies of modes with different l values (the so-called Small Spacing).Comment: 9 Pages, 5 Figures, Accepted by Astronomy and Astrophysics; alternative Download from ftp://ftp.deltascuti.net/pub/CloseFrequencies.pd

Inconsistent measurement and disclosure of non-contingent financial derivatives under IFRS: A behavioral perspective

The accounting principle of decomposing hybrid financial instruments into their derivative and non-derivative components is widely accepted as it results in a consistent treatment of hybrid instruments and economically equivalent combinations of contracts. On the other hand, non-contingent derivatives and their economic equivalents are not treated consistently under the mixed accounting model underlying IAS 39. This calls for a critical assessment. The conventional criticism regarding such inconsistencies refers to the creation of opportunities for earnings management. The aim of this paper is to add another perspective by including the effects of the related disclosure rules on risk perception by analysts and investors. Thereby, we consider both the presentation on the balance sheet and the additional disclosure in the notes according to IFRS 7. From extant literature, we diligently develop the hypothesis that, due to availability effects, entities using non-contingent derivatives are perceived to be riskier than entities using economic equivalents, although in fact the latter are riskier due to their exposure to additional counterparty risk. This bias in the perception of disclosures might thereby alter an entity’s costs of capital in a way not intended by IAS 39. In particular, we expect individuals to valuate entities using non-contingent derivatives lower than identical entities using economically equivalent contracts instead. We expect this difference in valuation to result from a higher cognitive availability of negative associations with derivatives than with non-derivatives. The underlying assumptions are outlined as they build a framework of hypotheses that could be tested in future research, particularly in experimental survey studies.