The Central Star of NGC 2346 as a Clue to Binary Evolution through the Common Envelope Phase

Abstract

We present an analysis of the binary central star of the planetary nebula NGC 2346 based on archival data from the International Ultraviolet Explorer (IUE), and new low- and high-resolution optical spectra (3700 - 7300Å). By including in the spectral analysis the contribution of both stellar and nebular continuum, we reconciled long-time discrepant UV and optical diagnostics and derive $E(B-V)=0.18\pm 0.01$. We re-classified the companion star as A5IV by analyzing the wings of the Balmer absorption lines in the high-resolution ($R=67000$) optical spectra. Using the distance to the nebula of 1400 pc from Gaia DR2, we constructed a photoionization model based on abundances and line intensities derived from the low-resolution optical spectra, and obtained a temperature of $T_{\mathrm{eff}}=130000$K and a luminosity $L=170$L${}_{\odot }$ for the ionizing star, consistent with the UV continuum. This analysis allows us to better characterize the binary system's evolution. We conclude that the progenitor star of NGC 2346 has experienced a common envelope phase, in which the companion star has accreted mass and evolved off the main-sequence.

Accepted in ApJ

References in corpus (5)

• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• A new library of theoretical stellar spectra with scaled-solar and alpha-enhanced mixtures
• Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way
• Close stellar binary systems by grazing envelope evolution

Cited by in corpus (1)

• Catalogue of central stars of planetary nebulae: Expanded edition