We have recently discovered a remarkable binary system containing a 0.17 Msuntidally distorted white dwarf and an unseen massive companion. LMWD 439 showspeak-to-peak radial velocity variations of 1020 km/s with an orbital period of88 minutes. The optical photometry rules out main-sequence companions. Based onthe mass function alone, there is 62% chance that the companion is more massivethan 1.4 Msun. To distinguish between a neutron star and a massive white dwarfcompanion, we propose a search for X-ray emission from LMWD 439. Newmilli-second pulsars with companions amenable to spectroscopy are of greatinterest, as they allow for a measurement of neutron star mass. If the companionis not a neutron star, this system would be a strong candidate for a Type Ia supernova progenitor.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2012-10-25T17:34:28Z/2012-12-14T19:27:30Z
Version
17.56_20190403_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 Mukremin Kilic, 2014, 'A Massive Companion to an Extremely Low-Mass White Dwarf', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-ouen8dt
