English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Supersoft X-ray sources constitute a class of astronomical objects characterized by extremely high X-ray luminosities and low effective temperatures, typically 20-100 eV. The canonical model for these sources involves a white dwarf accreting from a more massive companion in a binary system at a very high rate. The high soft X-ray luminosity is derived from steady or quasisteady nuclear burning of accreted hydrogen in a shell on the white dwarf surface. CAL 83 in the Large Magellanic Cloud (LMC) is often considered to be the prototype of the SSS class. CAL 83 exhibits large-scale anti-correlated X-ray and optical variability on a superorbital time-scale of ∼450 d, which has been explained by cyclic changes of the white dwarf envelope between a contracted high-temperature and an expanded low-temperature state. A detailed periodic analysis of the XMM-Newton lightcurves of CAL 83 has revealed a variable X-ray modulation with a period of ∼67 s. This oscillation was detected in all the X-ray high state lightcurves obtained during the 2000-2009 time period, as well as in the X-ray low state lightcurve with the highest count rate. The model proposed to explain the behaviour of this oscillation is related to the low-inertia magnetic accretor (LIMA) model described in the literature to explain the observed properties of dwarf nova oscillations (DNOs). In this model, the ∼67 s modulation originates in an equatorial belt-like structure in the envelope at the boundary with the inner accretion disc, with the belt weakly coupled to the white dwarf core via a ∼105 G magnetic field.

An adapted LIMA model for the 67-s periodicity in supersoft X-ray source CAL 83