X-ray bursts have recently been discovered in the Cepheids δ Cep and β Dor modulated by the pulsation cycle. We have obtained an observation of the Cepheid η Aql with the XMM-Newton satellite at the phase of maximum radius, the phase at which there is a burst of X-rays in δ Cep. No X-rays were seen from the Cepheid η Aql at this phase, and the implications for Cepheid upper atmospheres are discussed. We have also used the combination of X-ray sources and Gaia and 2MASS data to search for a possible grouping around the young intermediate mass Cepheid. No indication of such a group was found.
@article{arxiv.2105.13382,
title = {X-rays in Cepheids: XMM-Newton Observations of $\eta$ Aql},
author = {Nancy Remage Evans and Ignazio Pillitteri and Pierre Kervella and Scott Engle and Edward Guinan and H. Moritz Günther and Scott Wolk and Hilding Neilson and Massimo Marengo and Lynn D. Matthews and Sofia Moschou and Jeremy J. Drake and Joyce A. Guzik and Alexandre Gallenne and Antoine Mérand and Vincent Hocdé},
journal= {arXiv preprint arXiv:2105.13382},
year = {2021}
}