The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5

Abstract

The importance of long-period binaries for the formation and evolution of planetary nebulae is still rather poorly understood, which in part is due to the lack of central star systems that are known to comprise such long-period binaries. Here, we report on the latest results from the on-going Mercator-HERMES survey for variability in the central stars of planetary nebulae. We present a study of the central stars of NGC 1514, BD+30• 623, the spectrum of which shows features associated with a hot nebular progenitor as well as a possible A-type companion. Cross-correlation of high-resolution HERMES spectra against synthetic spectra shows the system to be a highly eccentric (e ∼ 0.5) double-lined binary with a period of ∼3300 days. Previous studies indicated that the cool component might be a horizontal branch star of mass ∼0.55 M , but the observed radial velocity amplitudes rule out such a low mass. If we assume that the nebular symmetry axis and binary orbital plane are perpendicular, then the data are more consistent with a post-main-sequence star ascending towards the giant branch. We also present the continued monitoring of the central star of LoTr 5, HD 112313, which has now completed one full cycle, allowing the orbital period (P∼2700 days) and eccentricity (e ∼ 0.3) to be derived. To date, the orbital periods of BD+30• 623 and HD 112313 are the longest to have been measured spectroscopically in the central stars of planetary nebulae. Furthermore, these systems, along with BD+33• 2642, comprise the only spectroscopic wide-binary central stars currently known.

A D’-type symbiotic binary in the planetary nebula SMP LMC 88

“…Due to the fact that central stars of PNe are discovered mainly using photometric monitoring, the known sample of central binary stars of PNe consists mainly of binaries with short orbital periods (Miszalski et al 2009). On the other hand SySt are binaries with some of the longest orbital periods, which makes SMP LMC 88 an important addition to the known population of binary central stars of PNe as the importance of longperiod central stars of PNe remains poorly understood (see Van Winckel et al 2014;Jones et al 2017;Miszalski et al 2018, and references therein).…”

Planetary nebulae with UVIT: A progress report

“…Recent observations show that the binary system has a period of 3306 days and eccentricity of 0.46. The estimates of the mass for the cooler secondary is about 2.3M and the hot primary is of 0.9M (Jones et al 2017). Ressler et al (2010) described the morphological structure of NGC 1514 (see their Fig.…”

An extremely hot white dwarf with a rapidly rotating K-type subgiant companion: UCAC2 46706450

“…There are also two other hot (pre-) WDs known, which are in a binary system with chromospherically active and rapidly rotating cool companions: LW Hya and LoTr 5. The latter is a wide binary in a highly eccentric orbit (e ≈ 0.3, P = 2700 d, Jones et al 2017) consisting of a hot pre-WD or WD, and the cool component, IN Com, is a rapidly rotating (v eq = 95 km s −1 , Strassmeier 2009) and magnetically active G5 III giant that also shows H α lineprofile variations (Kővári et al 2019). LW Hya is a resolved binary system composed of a hot DAO WD (the ionizing star of A 35, Ziegler et al 2012;Löbling et al 2019) and a magnetically active G8 III-IV-type companion (v eq = 127 km s −1 , Strassmeier 2009).…”