Gusty wind in the system of the infrared source RAFGL 5081

Abstract

For the first time, based on long-term spectral monitoring with high spectral resolution, the optical spectrum of the weak central star of the IR source RAFGL 5081 has been studied. The spectral type of this star is close to G5-8 II, and its effective temperature is Teff ~5400 K. An unusual spectral phenomenon was discovered: splitting of the profiles of broad, stationary absorption lines of medium and low intensity. The heliocentric radial velocities Vr of all components of metal absorption lines, the NaI D lines, and the H$\alpha$ line were measured for all the observation epochs. The constancy of the absorption lines rules out the possibility that the line splitting is due to binarity. The radial velocities of the wind components in the profiles of the NaI D and H$\alpha$ lines reach $-250$ and $-600$ km/s, respectively. These profiles have narrow components, whose number, depth, and position vary with time. The time variability and multicomponent structure of the profiles of the NaI D and H$\alpha$ lines indicates inhomogeneity and instability of the circumstellar envelope of RAFGL 5081. The presence of components with velocity Vr(IS)=$-65$ km/s in the NaI(1) lines provides evidence that RAFGL 5081 is located behind the Perseus arm, i.e., no closer than 2 kpc. It is noted that RAFGL 5081 is associated with the reflection nebula GN 02.44.7.