thesis_access.pdf (54.94 MB)
Download file

Development of a Southern Vilnius Standard Photometric System

Download (54.94 MB)
thesis
posted on 08.11.2021, 01:06 by Forbes, Murray Charles

The Vilnius Standard Photometric System is said to have several advantages over other photometric systems; reduction procedures free of systematic errors, a homogeneous set of standard stars, accurate dereddening, spectral classification and calibration of physical parameters for normal stars, and a good detection rate of abnormal stars. To investigate these, two southern, open star clusters (Omicron Velorum and Kappa Crucis) have been measured in the Vilnius system. The observations were used to derive astrophysical parameters such as age ((45 plus-minus l5)x106 and (10 plus-minus 3)x10 6 years respectively), composition (both solar metallicity), distance to the clusters (m-M = 5m.94 plus-minus 0.02 and 12m.18 plus-minus 0.05), interstellar reddening along our light of sight to the clusters (Ey-v = 0m.00 plus-minus 0.02 and 0m.31 plus-minus 0.09), and cluster membership probabilities for the individual stars. These compared favorably with the consensus of similar analyses made by observers using other photometric systems, with one exception being the distance to Kappa Crucis ( = 11m.59). As no stars further south than declination -26 degrees have been measured in the (original) Vilnius System, it was necessary to calibrate the local system to the standard system by measuring equatorial stars common to both. To alleviate this problem in the future, suitable southern stars were measured to form a southern standard system. Initially bright stars evenly spread across the sky were calibrated - this will ensure any future observing programme will have nearby standards. The next phase of the programme was to calibrate the E-region stars - this is a set of stars in common use as southern standards in other photometric systems. The final phase was to calibrate a sequence of stars near the south celestial pole - producing a set of stars so that the same standards can be observed at any time during the year. This southern standard system could not be completely established in the time available (it is approximately 50% finished), due to the larger than expected uncertainties in the measurements largely caused by the atmospheric effects of the Mount Pinatubo eruption.

History

Copyright Date

01/01/1996

Date of Award

01/01/1996

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

Author Retains Copyright

Degree Discipline

Physics

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Doctoral

Degree Name

Doctor of Philosophy

Victoria University of Wellington Item Type

Awarded Doctoral Thesis

Language

en_NZ

Victoria University of Wellington School

School of Chemical and Physical Sciences

Advisors

Dodd, Richard; Sullivan, Denis