Simulating Spectrophotometric Fluctuations of p‐Mode Oscillations in Solar‐like Stars

Abstract

ABSTRACTThe solar‐like spectrophotometric variations due to nonradial oscillations were simulated using a series of synthetic spectra computed and interpolated from stellar model atmospheres, each in complete equilibrium but at varying effective temperatures. The simulations are in good agreement with observations of the Sun done by others. We have demonstrated how the p‐mode signal is distributed as a function of wavelength between 350 and 1000 nm and more specifically how most of the signal is concentrated at shorter wavelengths. We attribute this to the high density of spectral lines at shorter wavelengths, as well as the tendency of the majority of the lines to weaken with increasing effective temperature. Our simulations are also in agreement with the observational studies that report that stronger lines show larger relative variations. We also reproduce the observed exceptions to this trend for lines such as Balmer lines and Ca ii H and K.After simulating a sample observing run, we show that it is very advantageous to take a ratio of two spectral bands, observed simultaneously, that exhibit completely different fractional changes. This is especially important for ground‐based observations that need to suppress scintillation noise and any other intensity fluctuations. Although strong absorption lines could be used for this purpose, a much better contrast can be obtained by using a wider spectral region, say between 350 and 500 nm, in conjunction with a region at much longer wavelengths, for example, in the 800 nm region. Our simple treatment of solar‐like oscillations also indicates that there is no signal loss due to lower resolution, since no single spectral line offsets the shift in the continuum at solar temperatures, as long as only the photometric signal, and not velocity shifts, is the primary interest.