(ORDO NEWS) — Using data from ESA’s XMM-Newton satellite and NASA’s NuSTAR space observatory, Indian astronomers conducted a broadband X-ray analysis of a unique intermediate polar object known as Paloma.
Cataclysmic variables (CVs) are binary star systems consisting of a white dwarf accreting material from a normal companion star.
They irregularly increase their brightness by a large amount and then return to a dormant state. Polaris are a subclass of cataclysmic variables, distinguished from other CPs by the presence of a very strong magnetic field in their white dwarfs.
In some PCs, accretion occurs through a truncated accretion disk when the white dwarf has a moderate magnetic field.
Such systems are known as intermediate polars (IPs). Observations have shown that in PP the magnetic white dwarf (WD) rotates asynchronously with the orbital period of the system and therefore produces fast oscillations with the rotation period.
Therefore, determining the exact period of rotation and the exact ephemeris of oscillations can be the key to revealing the PP nature of some CPs.
Paloma (other designations: RX J0524+42 and 1RXS J052430.2+424449) is a unique intermediate polar in which this WD asynchronism is significantly less (at the level of 14%) compared to other CPs (usually about 90%).
Therefore, in order to better understand this feature and identify the general properties of Palomar, Anirban Dutta and Vikram Rana from the Raman Research Institute in Bangalore, India, investigated this source.
“Using broadband X-ray data obtained simultaneously with XMM-Newton and NuSTAR, we attempted to provide a general description of the spectral properties of the system, as well as the temporal behavior of the system up to 40 keV,” the researchers write in their paper.
Observations have shown that the light curves folded in orbit have one broad hump-like structure with strong dips for soft and medium X-rays (0.3-10.0 keV). Astronomers suggest that this is due to radiation observed from at least one pole at any given time in the orbital motion of the white dwarf in Paloma.
Additionally, it is specified that these dips occur due to the presence of a complex inhomogeneous absorber. It shows a significant change depending on the phase of the orbit. Its maximum contribution during the orbital phase is estimated to range from 0.1 to 0.22.
The researchers suggest that this absorber is presumably introduced from an accretionary curtain or flow, including a preshock current.
In addition, the collected data allowed the researchers to measure the mass and radius of the white dwarf Paloma.
They found that its mass is about 0.74 solar masses, and its radius is approximately 7,400 kilometers. The authors of the study also found ionized emission lines in Paloma’s soft X-rays and a neutral iron K-alpha line, which is weaker than the ionized lines.
Contact us: [email protected]