Among the virgul6000 new white dwarfs (WDs) spectroscopically confirmed by the SloanDigital Sky Survey (SDSS) are three cool DAs and two cool DBs within 1. ofsuper-soft ROSAT All Sky Survey (RASS) sources. WDs at these relatively lowtemperatures (<23,000K) are not expected to be X-ray emitters, but the SDSSphotometric and spectroscopic data fail to identify any other obvious opticalcounterparts to the RASS sources to the SDSS limits (gvirgul23 mag in photometry). Wepropose 5 ksec XMM-Newton observations of these five SDSS WDs to obtain pinpointX-ray positions and improved flux measures for these objects. If XMM dataconfirm that the five WDs are X-ray sources, they will be of great interest; inparticular, theoretical work will be required to explain how such cool WDs can emit X rays.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2008-03-11T13:46:47Z/2008-03-11T17:55:44Z
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 Marcel Agueros, 2009, 'The Coolest X-ray Emitting White DwarfsquestionMark', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-g4lnep8
