The extreme-ultraviolet stellar characterization for atmospheric physics and evolution (ESCAPE) mission concept

Abstract

The extreme-ultraviolet stellar characterization for atmospheric physics and evolution (ESCAPE) mission concept",

Optical Detection of the 1.1 day Variability at the White Dwarf GD 394 with TESS

“…The TESS detection strengthens the connection between GD 394 and WD J1855+4207 suggested by Hallakoun et al (2018), both stars having high (>30,000 K) effective temperatures, high ionization-level metal absorption lines with strengths well above those predicted by their effective temperatures, and weak, many-hour period optical modulation (Maoz et al 2015). Proposed future missions such as ESCAPE (France et al 2019) could search for EUV variation at WD J1855+4207, confirming whether or not it is truly a GD 394 analog.…”

The evolution of the solar wind

“…From the depth of the light curve, one can infer how much mass has been blown out, and from the slope of the light curve, one can determine the CME speed (Mason et al 2016). The suggestion of detecting the stellar equivalent of solar coronal dimming is still in its first steps and will be explored with future instrumentations (France et al 2019). Some points still need to be elucidated, such as whether dimming could be detected in the case where CMEs are happening all the time, as could potentially be the case of young stars, or whether dimming could change the ''basal'' level of the stellar EUV emission to such an extent that one would not be able to disentangle particular CMEs.…”

Extreme Ultraviolet and Soft X-Ray Diffraction Efficiency of a Blazed Reflection Grating Fabricated by Thermally Activated Selective Topography Equilibration

“…In a similar manner to the Reflection Grating Spectrometer (RGS) on board XMM-Newton (den Herder et al 2001), an x-ray reflection grating spectrometer suitable for Lynx requires several thousand identical blazed gratings with fanned groove layouts stacked and aligned into modular arrays to intercept SXR radiation coming to a focus in a Wolter-I telescope (McEntaffer 2019). On the other hand, the Extreme-Ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission concept incorporates two blazed gratings with curved groove layouts that play a similar role for EUV radiation in a Hettrick-Bowyer-I telescope with the goal of characterizing high-energy radiation in habitable zones surrounding M-dwarfs and their impact on the atmospheres of exoplanets (France et al 2019). A main challenge from the standpoint of grating fabrication in any case is the realization of a lithographic process that can generate non-parallel groove layouts with high fidelity while also maintaining blazed grooves that enable high diffraction efficiency.…”

“…A main challenge from the standpoint of grating fabrication in any case is the realization of a lithographic process that can generate non-parallel groove layouts with high fidelity while also maintaining blazed grooves that enable high diffraction efficiency. In particular, sensitivity requirements for Lynx require that the sum of all propagating orders exceeds 40% diffraction efficiency across the SXR bandpass while ESCAPE baselines single-order diffraction efficiency of ∼60% in the EUV (McEntaffer 2019;France et al 2019).…”