IPHAS and the symbiotic stars. II. New discoveries and a sample of the most common mimics

TL;DR

This study uses the IPHAS survey to identify symbiotic stars and their mimics, confirming some candidates as genuine symbiotic systems and discovering other notable objects like Wolf-Rayet stars and young stellar objects.

Contribution

It provides a systematic search method for symbiotic stars in the IPHAS survey and reports new discoveries, including confirmed symbiotic stars and other stellar objects.

Findings

7 new confirmed symbiotic stars from 19 candidates

1 new D-type symbiotic system discovered

Identification of Wolf-Rayet stars and young stellar objects

Abstract

In a previous paper [arXiv:0712.2391], we presented the selection criteria needed to search for symbiotic stars in IPHAS, the INT Halpha survey of the Northern Galactic plane. IPHAS gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume. Follow-up spectroscopy at different telescopes worldwide of a sample of sixty two symbiotic star candidates is presented. Seven out of nineteen S-type candidates observed spectroscopically are confirmed to be genuine symbiotic stars. The spectral type of their red giant components, as well as reddening and distance, were computed by modelling the spectra. Only one new D-type symbiotic system, out of forty-three candidates observed, was found. This was as expected (see discussion in our paper on the selection criteria). The object shows evidence for a high density outflow expanding at a speed larger than 65 km/s. Most of the other candidates are lightly reddened classical T Tauri stars and more highly reddened young stellar objects that may be either more massive young stars of HAeBe type or classical Be stars. In addition, a few notable objects have been found, such as three new Wolf-Rayet stars and two relatively high-luminosity evolved massive stars. We also found a helium-rich source, possibly a dense ejecta hiding a WR star, which is surrounded by a large ionized nebula.