These included three series of annual reports on 'SS Cygni', on 'Long Period Variables' and on 'Three Irregular Variables
', namely R CrB, U Gem, and U Sct (see Table 1 for a list of papers on these three groups of stars).
Most "carbon stars" are long-period or slow irregular variables
, and these tend to be reddest when near minimum light.
--An introduction to variable stars including a description of the five classes, which were: I) temporary stars, II) long period variables, III) minor irregular variables, IV) short period variables & V) Algol stars.
The programme was further expanded to include the irregular variables U Gem and SS Cyg and the first meeting of the VSS took place on 1906 December 10.
Among these are some irregular variables
that the Hipparcos data hint may be semiregulars.
I find the method particularly useful for constructing good lightcurves of eclipsing binaries, Cepheids and irregular variables
. The increased accuracy can make a surprising difference to the quality of a lightcurve.
The fourth General Catalogue of Variable Stars classes it among the irregular variables
. But Maryland amateur Rick Wasatonic recently monitored it for several years from his backyard using an 8-inch Schmidt-Cassegrain telescope and a solid-state photometer.
These twin irregular variables
fluctuate between magnitude 8.0 and 8.5.
Checking further, she found that Be stars are rapidly spinning, irregular variables
, which slowly lose mass to a disk around the star's equator.