Open AccessLong‐term infrared variability of the UX Ori‐type star SV Cep
Author(s) -
Juhász A.,
Prusti T.,
Ábrahám P.,
Dullemond C. P.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.11208.x
Subject(s) - physics , infrared , astrophysics , stars , radiative transfer , context (archaeology) , spectral energy distribution , wavelength , envelope (radar) , circumstellar envelope , light curve , far infrared , astronomy , optics , galaxy , biology , paleontology , telecommunications , radar , computer science
We investigate the long‐term optical–infrared variability of SV Cep and explain it in the context of an existing UX Ori (UXOR) model. A 25‐month monitoring programme was completed with the Infrared Space Observatory in the 3.3–100 μm wavelength range. Following a careful data reduction, the infrared light curves were correlated with the variations of SV Cep in the V band. A remarkable correlation was found between the optical and the far‐infrared light curves. In the mid‐infrared regime, the amplitude of variations is lower, with a hint for a weak anti‐correlation with the optical changes. In order to interpret the observations, we modelled the spectral energy distribution of SV Cep assuming a self‐shadowed disc with a puffed‐up inner rim, using a two‐dimensional radiative transfer code. We found that modifying the height of the inner rim, the wavelength dependence of the long‐term optical–infrared variations is well reproduced, except the mid‐infrared domain. The origin of variation of the rim height might be fluctuation in the accretion rate in the outer disc. In order to model the mid‐infrared behaviour, we tested adding an optically thin envelope to the system, but this model failed to explain the far‐infrared variability. Infrared variability is a powerful tool to discriminate between models of the circumstellar environment. The proposed mechanism of variable rim height may not be restricted to UXOR stars, but might be a general characteristic of intermediate‐mass young stars.