SALT observations of southern post-novae

We report on recent optical observations of the stellar and the nebular remnants of 22 southern post-novae. In this study, for each of our targets, we obtained and analysed long-slit spectra in the spectral range 3500-6600 A and in H$\alpha$+NII narrow-band images. The changes in the emission lines' equivalent widths with the time since the outburst agree with earlier published results of other authors. We estimated an average value $\alpha$=2.37 for the exponent of the power law fitted to the post-novae continua. Our observations clearly show the two-component structure of the V842 Cen expanding nebulae, owing to the different velocities of the ejected matter. We discovered an expanding shell around V382 Vel with an outer diameter of about 12 arcsec.Comment: 24 pages, 19 figures, A&A accepte

Symbiotic stars in the Local Group of Galaxies

Preliminary results of the ongoing search for symbiotic binary stars in the Local Group of Galaxies are presented and discussed.Comment: Proceedings of Physics of Evolved Stars 2015: A Conference Dedicated to the Memory of Olivier Chesneau, Nice, 8-12 June 201

The Evolution of Technical Debt in the Apache Ecosystem

Software systems must evolve over time or become increasingly irrelevant says one of Lehman’s laws of software evolution. Many studies have been presented in the literature that investigate the evolution of software systems but few have focused on the evolution of technical debt. In this paper we study sixty-six Java open-source software projects from the Apache ecosystem focusing on the evolution of technical debt. We analyze the evolution of these systems over the past five years at the temporal granularity level of weekly snapshots. We calculate the trends of the technical debt time series but we also investigate the lower-level constituent components of this technical debt. We aggregate some of the information to the ecosystem level

The peculiar bursting nature of CP Pup

The classical nova CP Puppis has been observed to have particularly puzzling and peculiar properties. In particular, this classical nova displays occasional bursts in its long-term ASAS-SN light curve. Here, we report on five sectors of TESS data displaying two of these rapid bursts, lasting ∼1 d. Based on the estimated lower energy limits of the bursts, we discuss whether the bursts may be examples of micronovae resulting from localized thermonuclear explosion. Furthermore, its orbital period remains uncertain, with several inconsistent periodic signals appearing in spectroscopic and photometric observations at various wavelengths. Although we cannot unambiguously unravel the physical origin of the signals, the previously suggested nature of CP Puppis as a long orbital period system may be a viable explanation. The recurrence time of the bursts in CP Puppis, together with the unexplained variable modulations make it a prime candidate for intense monitoring.</p

Evolution of spin in the intermediate polar CC sculptoris

We report on spin variations in the intermediate polar and cataclysmic variable CC Scl, as seen by the Transiting Exoplanet Survey Satellite (TESS). By studying both the spin period and its harmonic, we find that the spin has varied since it was first observed in 2011. We find the latest spin value for the source to be 389.473(6)s, equivalent to 0.00450779(7) days, 0.02s shorter than the first value measured. A linear fit to these and intermediate data give a rate of change of spin ~-4.26(2.66)e10^-11 and a characteristic timescale tau~2.90e10^5 years, in line with other known intermediate polars with varying spin. The spin profile of this source also matches theoretical spin profiles of high-inclination intermediate polars, and furthermore, appears to have changed in shape over a period of three years. Such `spin-up' in an intermediate polar is considered to be from mass accretion onto the white dwarf (the primary), and we note the presence of dwarf nova eruptions in this source as being a possible catalyst of the variations