HD49798 is the only known X-ray binary with a hot subdwarf companion. Thecompact object (a white dwarf or a neutron star) has a spin period of 13 s andhas been steadily spinning up at 2x10^{-15} s/s for the last 20 years.Independently of its NS or WD nature, this spin-up is difficult to explain withthe angular momentum that accretion can supply. An alternative explanationimplies the presence of a young WD, still in the contracting phase. A newobservation must be secured as soon as possible in order to extend the phaseconnected timing solution of this unique binary and shed light on thenature ofthe compact object. This fulfil proposal was accepted in AO17 (C priority) butnot executed.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2020-02-27T06:27:36Z/2020-02-27T19:39:16Z
Version
18.02_20200221_1200
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Dr SANDRO MEREGHETTI, 2021, 'Long-term phase-connected timing of the unique X-ray binary HD49798', 18.02_20200221_1200, European Space Agency, https://doi.org/10.57780/esa-4ji0578
