Recent Cepheid X-ray observations have found the surprising result of increasedemission just after maximum radius, a pulsation phase when the photosphere isquiescent. Recent interferometric observations of Cepheids have foundcircumstellar envelopes (also surprising) which may be related and raisequestions of possible mass-loss and increased infrared (IR) flux which would beimportant in the use of the IR Leavitt (PL) relation for cosmology. Therequested XMM observation of the Cepheid V473 Lyr at the phase of maximum radiuswill provide a diagnostic of the elusive upper atmosphere activity, andspecifically the dependence on luminosity, mass, pulsation amplitude and mode.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2019-03-17T05:33:17Z/2019-03-17T17:29:57Z
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 Nancy Remage Evans, 2020, 'X-Rays from Cepheids\: Hints of Mass LossquestionMark', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-i8i2s0x
