Browsing by Subject "cataclysmic variables"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- PublicationCataclysmic Variables from Sloan Digital Sky Survey - V. The search for period bouncers continues(2023-11-01)
;Inight, K. ;Gänsicke, Boris T. ;Schwope, A. ;Anderson, S. F. ;Badenes, C. ;Breedt, E. ;Chandra, V. ;Davies, B. D.R. ;Gentile Fusillo, N. P. ;Green, M. J. ;Hermes, J. J. ;Huamani, I. Achaica ;Hwang, H. ;Knauff, K. ;Kurpas, J. ;Long, K. S. ;Malanushenko, V. ;Morrison, S. ;Quiroz C, I. J. ;Ramos, G. N.Aichele ;Roman-Lopes, A. ;Schreiber, M. R. ;Standke, A. ;Stütz, L. ;Thorstensen, J. R. ;Toloza, O. ;Tovmassian, G.Zakamska, N. L.SDSS-V is carrying out a dedicated survey for white dwarfs, single, and in binaries, and we report the analysis of the spectroscopy of 118 cataclysmic variables (CVs) and CV candidates obtained during the final plug plate observations of SDSS. We identify eight new CVs, spectroscopically confirm 53 and refute 11 published CV candidates, and we report 21 new or improved orbital periods. The orbital period distribution of the SDSS-V CVs does not clearly exhibit a period gap. In common with previous studies, the distribution shows that spectroscopically identified CVs have a larger proportion of short-period systems compared to samples identified from photometric variability. Remarkably, despite a systematic search, we find very few period bouncers. We estimate the space density of period bouncers to be , i.e. they represent only a few per cent of the total CV population. This suggests that during their final phase of evolution, CVs either destroy the donor, e.g. via a merger, or that they become detached and cease mass transfer. - PublicationThe C/N ratio from FUV spectroscopy as a constraint on evolution of the dwarf nova HS 0218 + 3229(2023-07-01)
; ;Gänsicke, Boris T. ;Guzmán-Rincón, Laura M. ;Marsh, Tom R. ;Szkody, Paula ;Schreiber, Matthias R. ;de Martino, Domitilla ;Zorotovic, Monica ;El-Badry, Kareem ;Koester, DetlevLagos, FelipeABSTRACT White dwarfs that accrete from non-degenerate companions show anomalous carbon and nitrogen abundances in the photospheres of their stellar components have been postulated to be descendants of supersoft X-ray binaries. Measuring the carbon-to-nitrogen abundance ratio may provide constraints on their past evolution. We fit far-ultraviolet spectroscopy of the cataclysmic variable HS 0218 + 3229 taken with the Cosmic Origins Spectrograph using Markov chain Monte Carlo methods, and found the carbon-to-nitrogen ratio is about one tenth of the Solar value $(\rm{\log \mathrm{[C/N]}}=-0.56\pm 0.15)$. We also provide estimates of the silicon and aluminium abundances, and upper limits for iron and oxygen. Using the parameters we derived for HS 0218 + 3229 we reconstruct its past. We calculated a grid of mesa models and implemented Gaussian process fits in order to determine its most likely initial binary configuration. We found that an initial mass of the donor of $M_{\rm donor;i}=0.90-0.98,\rm{\mathrm{M}_{\odot }}$ and an initial orbital period of Porb; i = 2.88 d (Porb; i = 3.12–3.16 d) for an assumed initial white dwarf mass of $\rm{M_{\mathrm{WD}}}_\mathrm{;i}=0.83\, \rm{\mathrm{M}_{\odot }}$$(\rm{M_{\mathrm{WD}}}_{\rm ;i}=0.60\, \rm{\mathrm{M}_{\odot }})$ can replicate the measured parameters. The low mass ratio, $M_{\rm donor;i} / \rm{M_{\mathrm{WD}}}_{\rm ;i} =1.08-1.18\, (1.5-1.63)$, suggests that the system did not go through a phase of hydrogen-burning on the white dwarf’s surface. However, we can not exclude a phase of thermal time-scale mass transfer in the past. We predict that HS 0218 + 3229 will evolve below the ≃ 76.2 ± 1 min period minimum for normal cataclysmic variables.