Astrophys. J., 905, 81-81 (2020/December-2)
Hubble Space Telescope snapshot survey for resolved companions of galactic Cepheids: final results.
EVANS N.R., GUNTHER H.M., BOND H.E., SCHAEFER G.H., MASON B.D., KAROVSKA M., TINGLE E., WOLK S., ENGLE S., GUINAN E., PILLITTERI I., PROFFITT C., KERVELLA P., GALLENNE A., ANDERSON R.I. and MOE M.
Abstract (from CDS):
Cepheids in multiple systems provide information on the outcome of the formation of massive stars. They can also lead to exotic end-stage objects. This study concludes our survey of 70 galactic Cepheids using the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) with images at two wavelengths to identify companions closer than 5''. In the entire WFC3 survey we identify 16 probable companions for 13 Cepheids. The 7 Cepheids having resolved candidate companions within 2'' all have the surprising property of themselves being spectroscopic binaries (as compared with a 29% incidence of spectroscopic binaries in the general Cepheid population). This is a strong suggestion that an inner binary is linked to the scenario of a third companion within a few hundred astronomical units. This characteristic is continued for more widely separated companions. Under a model where the outer companion is formed first, it is unlikely that it can anticipate a subsequent inner binary. Rather, it is more likely that a triple system has undergone dynamical interaction, resulting in one star moving outward to its current location. Chandra and Gaia data as well as radial velocities and HST/STIS and IUE spectra are used to derive properties of the components of the Cepheid systems. The colors of the companion candidates show a change in distribution at approximately 2000 au separations, from a range including both hot and cool colors for closer companions, to only low-mass companions for wider separations.
© 2020. The American Astronomical Society. All rights reserved.
Multiple stars - Intermediate-type stars - Cepheid variable stars - Star formation
View the reference in ADS
To bookmark this query, right click on this link: simbad:2020ApJ...905...81E and select 'bookmark this link' or equivalent in the popup menu