Publications (11)
Period Variations for the Cepheid VZ Cyg
Krittanon Sirorattanakul, Scott Engle, Joshua Pepper +4
The Cepheid Period-Luminosity law is a key rung on the extragalactic distance ladder. However, numerous Cepheids are known to undergo period variations. Monitoring, refining, and u…
X-rays in Cepheids: Identifying Low-Mass Companions of Intermediate-Mass Stars
Nancy Remage Evans, Scott Engle, Ignazio Pillitteri +12
X-ray observations have been made of a sample of 20 classical Cepheids, including two new observations (Polaris and {\it l} Car) reported here. The occurrence of X-ray flux around…
X-ray Observations of the Peculiar Cepheid V473 Lyr Identify A Low-Mass Companion
Nancy Remage Evans, Ignazio Pillitteri, Laszlo Molnar +17
V473 Lyr is a classical Cepheid which is unique in having substantial amplitude variations with a period of approximately 3.3 years, thought to be similar to the Blazhko variations…
Polaris: Mass and Multiplicity
Nancy Remage Evans, Gail Schaefer, Howard E. Bond +9
Polaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide () physical companion, the F-type dwarf Polaris B. Polaris itself…
Pulsation Period Change & Classical Cepheids: Probing the Details of Stellar Evolution
Hilding R. Neilson, Alexandra C. Bisol, Ed Guinan +1
Measurements of secular period change probe real-time stellar evolution of classical Cepheids making these measurements powerful constraints for stellar evolution models, especiall…
Resolved Companions of Cepheids: Testing the Candidates with X-Ray Observations
Nancy Remage Evans, Ignazio Pillitteri, Scott Wolk +7
We have made {\it XMM-Newton\/} observations of 14 Galactic Cepheids that have candidate resolved (5$\arcsec$) companion stars based on our earlier {\it HST\/} WFC3 imaging s…