Masses for Four Cepheids
Abstract
Velocities from IUE high dispersion spectra have provided mass ratios between a Cepheid and a blue companion for the systems SIT Cyg, S Mus, and V636 Sco. The proposed IUE high dispersion observations will produce a mass ratio for a new system, U Aql, with a percentage error as low as 14%, depending on the orbital velocity amplitude of the companion. They will also provide a second optimal spectrum for both S Mus and V636 Sco which will confirm the previous results at the second velocity extremum, reduce the uncertainty in the mass ratio by sqrt2 to 14%, and also provide an error estimate from comparison with the previous spectrum. For AW Per a spectrum will provide a preliminary mass function. confirmation that it is not a triple system, and information about the rotational velocity for a system which can be resolved by Hubble Space Telescope. These results, together with the SU Cyg results, are the only mass determinations for Cepheids to decide between the discordant evolutionary and pulsational masses.
- Publication:
-
IUE Proposal
- Pub Date:
- 1988
- Bibcode:
- 1988iue..prop.3049B