Sat, 04/08/2017 - 22:01
Hello Everyone!
I recently completed the AL Binocular Observing Program and looking at moving up to the AL Variable Star Program. The program mentioned that there are three types of variables to track: Miras, Semiregulars and Cataclysmic. I looked at the "Stars Easy To Observe" page and figured out that M is Mira and SR meant Semiregular, but what code is Cataclysmic? I am guessing U?
Thanks,
Preston
You are correct. I believe that the association of U with cataclysmic variables goes back to the discovery of U Geminorum. The General Catalogue of Variable Stars and VSX now recognize several classes of cataclysmic variables, including UG (similar to U Geminorum), UGSS (similar to SS Cygni), and UGZ (similar to Z Camelopardalis). The listing of variable types in the VSX section of the AAVSO website gives the full list of possibilities.
Nice post. Thanks for sharing!
json editor
Preston, Cataclysmic Variables (CVs in short) are the whole class of variable stars. Some of them can be found in catalogs (and in AAVSO VSX) simply as CV. They are including (but not limited to!) dwarf novae (DN or UG type) and classical Novae (N). Other major types of CVs are anti-novae (VY Scl type) which are labeled NL/VY in VSX (NL stands for "novalike" here), AM CVn stars (IBWD, interacting binary white dwarfs) and polars (AM Her type) with further subtypes AM, DQ and IP (intermediate polars).
Thus, we have roughly the following hierarchy here:
Types: N, UG, VY, AM, IBWD
Subtypes: NA, NB, NR; UGSS, UGZ, UGSU, UGER, UGWZ, UG+IBWD; NL/VY; AM, DQ, IP
So, to find all cataclysmic variables in AAVSO VSX you should search for CV%, N%, UG%, AM%, DQ%, IP%, NL/VY%, IBWD% types at Query Level 2. % is important here because many CVs have uncertain classification marked with : and/or belong to several classes of variability at once. The same star (if it is a binary!) can belong to five major classes simultaneously: cataclysmic, eclipsing, pulsating, flaring and rotating. That can be shown in catalogs as UGWZ+ZZ+E. If you search for UGWZ, you only find 112 stars in VSX. But extending the search to UGWZ% will give you 143 stars, now including prototype WZ Sge herself.
Denis (DDE)
Just for the record, you can search for all cataclysmic variables in VSX by choosing "Cataclysmic variables" from the list box to the right of the "Variability type" text box, without having to specify any type or wildcards.
Patrick
Just astonished that any reputable organisation isn't using the standard type identifiers. 'U' in this context means nothing!