Infrared Excess in the Be Star Delta Scorpii

TL;DR

This study presents infrared observations of delta Scorpii, analyzing its circumstellar disk's properties and variability through modeling and spectroscopy to understand its dynamics.

Contribution

It introduces a detailed non-LTE modeling approach to constrain the density distribution of delta Scorpii's circumstellar disk based on infrared excess and Halpha data.

Findings

Infrared magnitudes remained consistent over 10 months.

The observed infrared excess aligns with the radiative equilibrium model.

Disk density distribution shows variability over time.

Abstract

We present infrared photometric observations of the Be binary system delta Scorpii obtained in 2006. The J,H and K magnitudes are the same within the errors compared to observations taken 10 months earlier. We derive the infrared excess from the observation and compare this to the color excess predicted by a radiative equilibrium model of the primary star and its circumstellar disk. We use a non-LTE computational code to model the gaseous envelope concentrated in the star's equatorial plane and calculate the expected spectral energy distribution and Halpha emission profile of the star with its circumstellar disk. Using the observed infrared excess of delta Sco, as well as Halpha spectroscopy bracketing the IR observations in time, we place constraints on the radial density distribution in the circumstellar disk. Because the disk exhibits variability in its density distribution, this work will be helpful in understanding its dynamics.