Astronomers from Columbia University have shed new light on the intriguing intermediate polar CTCV J2056–3014, which hosts one of the fastest-spinning white dwarfs known to science. By utilizing a suite of advanced X-ray observatories, the researchers have uncovered insights into the nature of this peculiar binary system and its remarkable white dwarf.
Unveiling the Secrets of a Rapidly Spinning White Dwarf
Some 853 light-years away, CTCV J2056–3014 was discovered in 2010 as the most nearby intermediate polar (IP). This system is remarkable not only because of its unique nature but also due to the extremely short spin period of the white dwarf, which reaches a speed of 29.6 seconds, making it one of the fastest spinning cataclysmic variables (CVs) detected by astronomers.
A CV is a binary star system comprising a white dwarf (the smaller, denser component) orbiting or infalling onto its larger, brighter companion which naturally would be of spectral type A to K and quite like the Sun. They are characterized by outbursts — random, irregular brightening events— which can be hundreds of thousands what the system was seen being in its so-called quiescent state. Due to the strong magnetic field of the white dwarf in a polar, this WD is very close to having its spin period locked with the orbital period (so not quite being a synchronous rotator due to some coupling processes going through), while an intermediate polar (IP) is an asynchronous pole having similar modest magnetic fields allowing accretion discs truncated.
The X-ray Secrets of CTCV J2056–3014 Uncovered
In order to see this, the research team carried out a multi-wavelength investigation of CTCV J2056–3014 using advanced X-ray observatories mappings thanks to the use vairety of and most notably XMM-Newton satellite by ESA; NuSTAR telescope by NASA; and Neutron star Interior Composition Explorer (NICER) on-boarded on the International Space Station.
Pulsed component This system has a pulsed profile with typical one component having the broad peak, roughly 25% modulation (observations currently not available. More significantly, an optical flare that produced a fourfold increase in unabsorbed X-ray flux was identified in November 2022. It means a highly intricate accretion process is present in the system.
The properties of CTCV J2056–3014, the researchers concluded, are typically similar to low-resolution data for all published FSCVs and include low plasma temperatures and a lack of significant X-ray absorption at low energies. Nevertheless, the identification of an iron line in a “low” state, and the non-magnetic CV nature of the source probably means that it isn’t a Polar – or possibly just doesn’t behave as like one all the time.
Unraveling the identity of CTCV J2056–3014
The X-ray spectrum data enabled the researchers to determine the mass of the white dwarf in CTCV J2056–3014, placing it between 0.7 and 1.0 solar masses — a common value for known CV systems.
The scientists will release another publication studying the optical properties of CTCV J2056–3014 in depth, which might give insights into whether this intriguing cataclysmic variable is actually classified as a true member. What the rapid rotation of this white dwarf and its binary system more generally reveal about the diverse populations of stellar companions is a key question that will ultimately unlock their evolution.
