The Dynamical Mass of the Bright Cepheid Polaris

Details The Dynamical Mass of the Bright Cepheid Polaris The Dynamical Mass of the Bright Cepheid Polaris

Jul 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006hst..prop10891e&link_type=abstract

HST Proposal ID #10891. Cycle 15

Astronomy and Astrophysics

Astronomy

Scientific paper

Cepheid variables are of central importance in Galactic and extragalactic astronomy. They are the primary standard candles for measuring extragalactic distances, and they provide critical tests of stellar-evolution theory. Surprisingly, however, until now there was not a single Cepheid with a purely dynamical measurement of its mass. Polaris alpha UMi is the nearest and brightest of all Cepheids. It offers the unique opportunity to measure the dynamical mass of a Cepheid, because it is in a binary system for which a single-lined spectroscopic orbit is already available. In Cycle 14, we resolved the system in the UV using ACS/HRC, thus providing the first direct detection of the companion, as well as a first approximation to the dynamical mass. In the present proposal we request one HST orbit per year for the next 3 Cycles, in order to refine the visual orbit. Combined with the HST/FGS parallax see below, this program will provide an accurate mass for the Cepheid the error should be about 0.5 Msun by Cycle 17, and the only one based purely on dynamical information. Only HST's combination of high spatial resolution and UV sensitivity can achieve this result. The parallax is a key ingredient in the mass determination. In an ongoing multi-year program GO-9888, GO-10113, GO-10482, we are using the FGS to improve significantly upon the Hipparcos parallax of Polaris. The continued ACS imaging proposed here will thus provide extremely valuable astrophysical information from a very modest additional investment of observing time.

Affiliated with

Also associated with

No associations

Rating

The Dynamical Mass of the Bright Cepheid Polaris does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Dynamical Mass of the Bright Cepheid Polaris, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Dynamical Mass of the Bright Cepheid Polaris will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1792966