Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae

Details Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae

Feb 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995a%26a...294..453v&link_type=abstract

Astronomy and Astrophysics (ISSN 0004-6361), vol. 294, no. 2, p. 453-468

Astronomy and Astrophysics

Astrophysics

34

Asymptotic Giant Branch Stars, Stellar Evolution, Stellar Models, Stellar Oscillations, Variable Stars, Hertzsprung-Russell Diagram, Mathematical Models, Planetary Nebulae, Stellar Envelopes, Stellar Magnitude

Scientific paper

We compare the observed evolutionary and pulsational characteristics of the variable post-Asymptotic Giant Branch (AGB) star FG Sge with theoretical models. Therefore, we had to reconstruct the evolutionary track on the theoretical Hertzsprung-Russell (HR) diagram from the apparent magnitudes for the years 1890-1992. The variability of FG Sge was investigated including data from the early Sonneberg photographic monitoring campaigns. It appears that the reconstructed evolutionary track, from presumably spectral type O3 around 1880 to K2 at about 1992 runs slightly steeper on the HR diagram than what stellar evolution canonically shows the post-AGB stars after a late He-shell flash. A period analysis applied to the photographic observations performed in the 1930s revealed FG Sge to have been pulsating (P approximately equals 5 d) already when the temperature was of the order of 20 000 K. Theoretical stability analyses of appropriate stellar envelopes agree well with such findings. The best fitting of theoretical models with the observed pulsational characteristics requires M = 0.8 solar mass and log L/solar luminosity = 4.08 which corresponds to a distance of 3.9 kpc. The deep fading and the simultaneous blue colors are attributed to the formation of a dense circumstellar dust cloud in front of the star and by scattering of the stellar light by parts of the cloud. A causal connection between the expulsion of the cloud and the decay of the pulsation is not inconceivable.

Affiliated with

Also associated with

No associations

Rating

Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae 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 Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deductions from the reconstructed evolutionary and pulsational history of FG Sagittae will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1629162