Vilnius photometric system is a medium-band seven-colour photometric system (UPXYZVS), created in 1963 by Vytautas Straižys and his coworkers. This system was highly optimized for classification of stars from ground-based observations. The system was chosen to be medium-band, to ensure the possibility to measure faint stars.
The temperature classification of early-type stars is based on Balmer jump (Balmer discontinuity). To measure it one must have two bandpasses placed in the ultraviolet, one beyond the Balmer jump (U magnitude) and another after the jump (X magnitude). The Y bandpass is near the breakpoint of the interstellar extinction law (interstellar extinction in the 300–800 nm region can be approximated by two straight lines, which intersect at ~435.5 nm). The P magnitude is placed exactly on the Balmer jump in order to provide separation for luminosity classes of B-A-F stars.
The Z magnitude is placed on the Mg I triplet and the MgH molecular band. It is sensitive to the luminosity classes of G-K-M stars. Finally, the V magnitude is chosen to coincide with a similar bandpass in the UBV system. It provides the possibility to relate these two photometric systems. S bandpass coincides with H alpha line position and provides information about emission or absorption phenomena in that line.
Normalization
Colour indices of the system were normalized to satisfy the condition:
U-P = P-X = X-Y = Y-Z = Z-V = V-S = 0
for unreddened O-type stars.
Mean wavelength and half-widths of response functions
vilnius, photometric, system, this, article, does, cite, sources, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, august, 2021, learn,. This article does not cite any sources Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Vilnius photometric system news newspapers books scholar JSTOR August 2021 Learn how and when to remove this template message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations August 2021 Learn how and when to remove this template message Vilnius photometric system is a medium band seven colour photometric system UPXYZVS created in 1963 by Vytautas Straizys and his coworkers This system was highly optimized for classification of stars from ground based observations The system was chosen to be medium band to ensure the possibility to measure faint stars Contents 1 Selection of bandpasses 2 Normalization 3 Mean wavelength and half widths of response functions 4 See also 5 SourcesSelection of bandpasses EditThe temperature classification of early type stars is based on Balmer jump Balmer discontinuity To measure it one must have two bandpasses placed in the ultraviolet one beyond the Balmer jump U magnitude and another after the jump X magnitude The Y bandpass is near the breakpoint of the interstellar extinction law interstellar extinction in the 300 800 nm region can be approximated by two straight lines which intersect at 435 5 nm The P magnitude is placed exactly on the Balmer jump in order to provide separation for luminosity classes of B A F stars The Z magnitude is placed on the Mg I triplet and the MgH molecular band It is sensitive to the luminosity classes of G K M stars Finally the V magnitude is chosen to coincide with a similar bandpass in the UBV system It provides the possibility to relate these two photometric systems S bandpass coincides with H alpha line position and provides information about emission or absorption phenomena in that line Normalization EditColour indices of the system were normalized to satisfy the condition U P P X X Y Y Z Z V V S 0for unreddened O type stars Mean wavelength and half widths of response functions EditU P X Y Z V SMean wavelength nm 345 374 405 466 516 544 656Half width nm 40 26 22 26 21 26 20See also EditUBV photometric systemSources EditStraizys V Multicolor Stellar Photometry Pachart Pub House 1992 570 pages This Lithuania related article is a stub You can help Wikipedia by expanding it vte This astronomy related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Vilnius photometric system amp oldid 1038150045, wikipedia, wiki, book, books, library,
