Naming variable stars
To name variable stars , a system based on Bayer names was developed, in which an identifier followed by the Latin genitive of the constellation name is used.
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Since only a few variable stars were known in earlier centuries , it seemed sensible to use the Latin capital letters from R as an identifier, e.g. R Lyrae . This should exclude the double assignment of large Latin letters, which were also used in the Bayer names in the constellation Swan up to Q. Until 1836, the star naming only reached the letter S in the constellation Snake .
With the advent of photography in the 19th century, however, the number of variables discovered rose rapidly. Instead of long series of visual measurements , it was now possible to compare photos of the sky taken at different distances. As a result, however, the naming system for the letter Z reached its limit, although in many constellations there were still other variables to be named. The Bayer names once had a similar experience. The naming system was therefore expanded to include double letters, first from RR to ZZ , then again from AA to QZ .
When this too was no longer sufficient, the Dutch astronomer Albertus Antonie Nijland suggested redesigning the naming system from scratch and simply using the designations V1, V2, V3, ...: the V for variable , followed by a sequential number . However, as some of the names given were already firmly established, e.g. for RR Lyrae stars and W Ursae Maioris stars , this new system was only used from number V335 .
The current naming system for variable stars is therefore for each constellation :
- Start at R and continue to Z.
- Continue with RR, RS,… RZ, then SS, ST,… SZ, TT,… TZ etc. to ZZ.
- Continue to use AA, AB, ... AZ, BB, BC, ... BZ etc. to QZ. The combinations AJ, BJ,… IJ and JJ to JZ are omitted.
- Finally, after all 334 possible letter combinations, finish the alphabetical naming and continue numbering with V335, V336, V337, ...
Examples of stars named in this way are R Leonis , VY Canis Majoris and V373 Scuti .
example
Using R Leonis , UY Scuti and VV Cephei , the procedure should be clarified:
| The letters R - Z are used for the first 9 stars: | R. | S. | T | U | V | W. | X | Y | Z | ||
| The letters RR - RZ are used for the next 9 stars: | RR | RS | RT | RU | RV | RW | RX | RY | RZ | ||
| The letters SS - SZ are used for the next 8 stars: | SS | ST | SU | SV | SW | SX | SY | SZ | |||
| The letters TT - TZ are used for the next 7 stars: | TT | TU | TV | TW | TX | TY | TZ | ||||
| The letters UU - UZ are used for the next 6 stars: | UU | UV | UW | UX | UY | UZ | |||||
| The letters VV - VZ are used for the next 5 stars: | VV | VW | VX | VY | VZ |
etc.
That means:
- R Leonis is the 1st variable star discovered in the constellation Leo .
- UY Scuti : 9 + 9 + 8 + 7 + 5 = 38, i.e. H. UY Scuti is the 38th variable star discovered in the constellation Scutum .
- VV Cephei : 9 + 9 + 8 + 7 + 6 + 1 = 40, i.e. H. VV Cephei is the 40th variable star discovered in the constellation Cepheus .