It's their luminosity class taken from the Morgan-Keenan spectral classification (and the Hertzsprung-Russell diagram).
V means it's a main sequence star.
A number of different luminosity classes are distinguished[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-CDS-18"][17][/URL]
V means it's a main sequence star.
A number of different luminosity classes are distinguished[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-CDS-18"][17][/URL]
- 0 or Ia+ (hypergiants or extremely luminous supergiants). Example: Cygnus OB2#12 (B3-4Ia+)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Caballero-Nieves-19"][18][/URL]
- Ia (luminous supergiants). Example: Eta Canis Majoris (B5Ia)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Prinja-20"][19][/URL]
- Iab (intermediate luminous supergiants). Example: Gamma Cygni (F8Iab)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-GrayDF-21"][20][/URL]
- Ib (less luminous supergiants). Example: Zeta Persei (B1Ib)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Naz.C3.A9-22"][21][/URL]
- II bright giants. Example: Beta Leporis (G0II)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Lyubimkov-23"][22][/URL]
- III normal giants. Example: Arcturus (K0III)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-GrayRO-24"][23][/URL]
- IV subgiants. Example: Gamma Cassiopeiae (B0.5IVpe)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Shenavrin-25"][24][/URL]
- V main-sequence stars (dwarfs), Example: Achernar (B6Vep)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Naz.C3.A9-22"][21][/URL]
- sd (prefix) subdwarfs. Example: HD 149382 (sdB5)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Cenarro-26"][25][/URL]
- D (prefix) white dwarfs.[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-27"][nb 2][/URL] Example: van Maanen 2 (DZ8)[URL="https://en.wikipedia.org/wiki/Stellar_classification#cite_note-Sion-28"][26][/URL] (taken from wikipedia)