Newly discovered X-ray binary system contains a white dwarf, observations find

Astronomers from the Pennsylvania State College (PSU) and elsewhere have noticed an X-ray binary system referred to as CXOU J005245.0-722844. They detected an X-ray outburst from this binary and located that it harbors a white dwarf star. The findings have been introduced in a analysis paper published August 2 on the pre-print server arXiv.

X-ray binaries are composed of a traditional star or a white dwarf (WD) transferring mass onto a compact neutron star or a black hole. Based mostly on the mass of the companion star, astronomers divide them into low-mass X-ray binaries (LMXBs) and high-mass X-ray binaries (HMXBs).

Be/X-ray binaries (Be/XRBs) are the most important subgroup of HMXBs. These techniques include Be stars and, normally, neutron stars, together with pulsars. Observations have discovered that the majority of those techniques showcase weak persistent X-ray emission that’s interrupted by outbursts lasting a number of weeks.

CXOU J005245.0-722844 was first recognized as an X-ray supply in 2009. Additional observations have revealed that it’s a Be/XRB within the Small Magellanic Cloud (SMC) consisting of an OBe main sequence star and a compact object.

Now, a staff of astronomers led by PSU’s Thomas Gaudin has employed NASA’s Swift spacecraft and varied ground-based telescopes to analyze CXOU J005245.0-722844.

The observational campaign detected a brand new very quick and highly-luminous X-ray outburst from this supply in late Could 2024. The X-ray spectrum for this technique through the outburst was discovered to be supersoft in nature.

Additional evaluation of the X-ray spectrum of CXOU J005245.0-722844 has revealed that the system accommodates a white dwarf. The outcomes recommend that this object is probably going an enormous carbon and oxygen (CO) WD on the higher restrict of its mass vary—with a mass of about 1.2 solar plenty.

The research confirmed that the opposite object within the system is an early-type OBe star. Subsequently, CXOU J005245.0-722844 is up to now solely the seventh candidate Be/WD X-ray binary, and the fifth such system recognized in SMC.

Making an attempt to clarify the current outburst of CXOU J005245.0-722844, the authors of the paper assume that the X-ray flash was almost definitely the preliminary thermonuclear phase of a nova outburst on the floor of the white dwarf. They added that the speedy decay time of the occasion signifies that little or no mass was ejected through the outburst.

The observations additionally discovered that the orbital interval of CXOU J005245.0-722844 has decreased from 17.55 to 17.14 days over the course of two years. Nevertheless, this variation is just not properly understood, and detailed mass transfer dynamical modeling is required in an effort to clarify such conduct.

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