Title: The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5 Author: David Jones, Hans Van Winckel, Alba Aller, Katrina Exter, Orsola De Marco The importance of long-period binaries on the formation and evolution of planetary is still rather poorly understood, in part due to the lack of central star systems 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 solar masses but the observed radial velocity amplitudes rule out such a low mass. Assuming the nebular symmetry axis and binary orbital plane are perpendicular, 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. Read more (896kb, PDF)
Title: Spectral analysis of BD+30°623, the peculiar binary central star of the planetary nebula NGC 1514 Author: A. Aller, B. Montesinos, L. F. Miranda, E. Solano, A. Ulla NGC 1514 is a complex planetary nebula with a peculiar binary central star (BD+30°623) consisting of a cool star and a hot companion. To date, the parameters of the two stars have not been firmly established. We present a detailed spectral analysis of BD+30°623 based on intermediate-resolution CAFOS optical spectra and IUE ultraviolet spectra with the goal of deriving the parameters of the two stars. For this purpose, we used an extensive composite grid of Kurucz and Tübingen NLTE Model-Atmosphere spectra. From the fitting procedure, in terms of the minimum chi² method, the best models obtained correspond to an Horizontal-Branch A0 star with T_eff = 9850±150 K, log g = 3.50±0.25, and a hot companion with T_eff between 80000 K and 95000K and a log g \simeq 5.5. To our knowledge, this is the first time that the parameters of both stars have been determined accurately through a detailed spectroscopic analysis. Read more (152kb, PDF)
NGC 1514 (also Crystal Ball Nebula and PK 165-15.1) is a magnitude +9.43 planetary nebula located about 600 light-years away in the constellation Taurus.
The planetary nebula was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Windsor Road in Slough, Berkshire, on the 13th November 1790.
Right Ascension 04h 09m 16.984s, Declination +30° 46' 33.47"
It has since been conjectured that the nebula in fact envelops a tightly orbiting double star with a period of up to 10 days. Gas is presumably expanding away from the larger star of the pair.Read more
It has since been conjectured that the nebula in fact envelops a tightly orbiting double star with a period of up to 10 days. Gas is presumably expanding away from the larger star of the pair.
NASA's Wide-field Infrared Survey Explorer has captured images of a dying star that resembles a glowing jellyfish floating at the bottom of a dark, speckled sea.
A new image from NASA's Wide-field Infrared Survey Explorer shows what looks like a glowing jellyfish floating at the bottom of a dark, speckled sea. In reality, this critter belongs to the cosmos -- it's a dying star surrounded by fluorescing gas and two very unusual rings.The object, known as NGC 1514 and sometimes the "Crystal Ball" nebula, belongs to a class of objects called planetary nebulae, which form when dying stars toss off their outer layers of material. Ultraviolet light from a central star, or in this case a pair of stars, causes the gas to fluoresce with colourful light. The result is often beautiful -- these objects have been referred to as the butterflies of space.