Hubble Space Telescope Snapshot Survey for Resolved Companions of Galactic Cepheids: Final Results

Kavli Affiliate: Moritz Guenther

| First 5 Authors: Nancy Remage Evans, H. Moritz Guenther, Howard E. Bond, Gail H. Schaefer, Brian D. Mason

| Summary:

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 {it Hubble
Space Telescope} (HST) Wide Field Camera~3 (WFC3) with images at two
wavelengths to identify companions closer than $5arcsec$. In the entire WFC3
survey we identify 16 probable companions for 13 Cepheids. The seven 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). That is
a strong suggestion that an inner binary is linked to the scenario of a third
companion within a few hundred~AUnull. 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. {it
Chandra} and {it Gaia} data as well as radial velocities and HSTSTIS and
{it 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

| Search Query: ArXiv Query: search_query=au:”Moritz Guenther”&id_list=&start=0&max_results=10

Read More

Leave a Reply