Hypergiant V1302 Aql in 2001-2014

TL;DR

This study analyzes spectral features and velocity fields of the hypergiant V1302 Aql from 2001 to 2014, revealing stable velocities and indicating the star's evolutionary phase near the high-temperature boundary of the Yellow Void.

Contribution

It provides a detailed spectroscopic analysis over 13 years, showing stability in spectral line velocities and insights into the star's evolutionary status, which is a novel long-term observational study of this hypergiant.

Findings

Radial velocities of lines are close to the systemic velocity.

Absorption components indicate clumps moving toward the star.

Star is near the high-temperature boundary of the Yellow Void.

Abstract

We present the results of a study of spectral features and the velocity field in the atmosphere and the circumstellar envelope of the hypergiant V1302 Aql, the optical counterpart of the IR source IRC+10420, based on high-resolution spectroscopic observations obtained in 2001-2014. We measured radial velocities of the following types of lines: forbidden and permitted pure emissions, absorption and emission components of lines of ions, pure absorptions (e.g., HeI, SiII), and interstellar components of the NaI D-lines, KI, and DIBs. The heliocentric radial velocity measured for pure absorptions as well as for the forbidden and permitted pure emissions is close to the systemic radial velocity and equal to Vr=63.7$\pm$0.3, 65.2$\pm$0.3, and 62.0$\pm$0.4 km/s, respectively. Positions of the absorption components of the lines with inverse P Cyg profiles are stable and indicate the presence of clumps moving toward the star with a velocity of $\sim$20 km/s. The average radial velocity of the DIBs is Vr(DIB)=4.6$\pm$0.2 km/s. Comparison of the absorption lines observed in 2001-2014 and those in earlier data shows no noticeable variations. We conclude that the hypergiant reached a phase of slowing down (or termination) of the effective temperature growth and is currently located near the high-temperature boundary of the Yellow Void in the Hertszprung-Russell diagramme.