The 77-81 photometric system
Basic Reference
Cook K.H., Aaronson M. 1989, AJ 97, 923
Abstract
This paper presents the definition of an intermediate-band photometric color
system for the study of late-type stars. One of the intermediate passbands is
centered on a region of TiO absorption at 7750Å (77), and the other is
centered on a region of CN absorption at 8100Å (81). The 77 - 81 color of
late-type stars clearly distinguishes carbon stars from M stars and is easily
measured using modern area detectors such as CCDs. It has been used in a
photometric technique where broadband, V and I images identify red stars and
the 77 - 81 color is used to classify them as C or M type. The 77 - 81 color
is also a single-sideband TiO band-strength measure and correlates well with
M type and true band-strength measures. The 77 - 81, TiO band strength as a
function of V - I color for a sample of nearby giants (Mould and Siegel 1982)
is presented. The establishment of the 77 - 81 system extends the use of
77 - 81 data from identification and classification of late-type stars to the
measurement of TiO band strengths in M stars, which it identifies.
Content
Access to the data and references
Asiago Database on Photometric System (ADPS)
Filters
Manufactured by Spectro-Optics in Sylmar, California
- 77 :
- central wavelength: 7752A
- Full width at half-maximum transmission: 284A
- 81 :
- central wavelength: 8104A
- Full width at half-maximum transmission: 365A
Please, send your
commentsto epaunzen@physics.muni.cz
epaunzen@physics.muni.cz
Last update: 21 May 1996