EPJ Web of Conferences 152, 03009 (2017)
https://doi.org/10.1051/epjconf/201715203009

Between Cepheids and the Cosmos

¹ Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge MA 02138, USA
² Villanova University, Department of Astronomy, Villanova, PA 19085, USA
³ University of Toronto, Dept of Astronomy 
 Astrophysics, 60 St. George St. Toronto, ON M5S 3H4, Canada
⁴ Iowa State University, A313E Zaffarano, Dept. of Physics and Astronomy, Ames, IA 50010, USA
⁵ MIT Haystack Observatory, Westford MA, 01886, USA
⁶ MIT Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge MA 02139, USA

^* nevans@cfa.harvard.edu
^** scott.engle@villanova.edu
^*** edward.guinan@villanova.edu
^**** neilson@astro.utoronto.ca
^† mmarengo@iastate.edu
^‡ lmatthew@haystack.mit.edu
^§ hgunther@mit.edu

Published online: 8 September 2017

Abstract

The X-ray observations of three classical Cepheids produce a surprising result. At approximately the phase of maximum radius there is a sharp increase in X-ray flux above the normal “quiescent” level. The relation of this new upper atmosphere diagnostic to other phenonena above the photosphere is discussed.