A variability sample catalogue selected from the Sydney Observatory Galactic Survey
Abstract
Context: A set of 55×103 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892-1932 along the galactic equator section lin[275°,335°] with galactic latitude bin[-7°,7°]. Short-term (30 min) and long-term (decades) magnitude variations in the data set are analyzed.
Aims: Evidence is sought for a correlation between short-term and long-term variabilities which would identify stars in a non-quiescent phase.
Methods: We use a reduced proper motion diagram to classify the stars in our sample into probable dwarfs, giants and other types. The validity of the kinematical classification is checked using objective-prism spectroscopic classification for 10× 103 early-type stars. A search is made for statistical correlations between our variability indicators and physical and kinematical stellar properties.
Results: We find that suspected photospheric activity for giant and dwarf stellar candidates is correlated with the time to cross the galactic thin disk. We estimate a significant apparent B-magnitude variation of ±0.25 over the 40 years of photographic observations, and candidates for monitoring for possible photospheric activity at the present time are selected employing a statistical colour-diagram which uses the total proper motion component as a distance indicator.
Conclusions: Follow up studies of our tentative findings are suggested. Toward this aim the derived data for the set of 55× 103 stars with variability information is archived as the variability Sample Catalogue. The data for a set of 2.4× 105 stars along the section of the galactic equator lin[275°,335°], mid b mid ≤ 7°, and a set of of 1.7× 105 stars along the section of the galactic meridian 330° ±5°, bin[-64°,-7°] is also archived as a quick-look facility for seeking long-term magnitude changes since the century-old photographic observations were obtained.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- September 2009
- DOI:
- 10.1051/0004-6361/200810798
- Bibcode:
- 2009A&A...503.1023F
- Keywords:
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- surveys;
- stars: variables: general