Add Concepts to White Dwarfs, submitted by Sarah Weissman (STScI) 8/8/2016

[katieefrey]

Added more subtypes of White dwarf stars. See http://www.daviddarling.info/encyclopedia/W/whitedwarf.html.

... -->White dwarfs-->DA stars
... -->White dwarfs-->DB stars
... -->White dwarfs-->DC stars
... -->White dwarfs-->DO stars-->BL Herculis stars ... -->White dwarfs-->DO stars-->PG 1159 stars ... -->White dwarfs-->DO stars
... -->White dwarfs-->DZ stars
... -->White dwarfs-->DQ stars

[katieefrey]

For the new sub types of White dwarf stars, the source document (http://www.daviddarling.info/encyclopedia/W/whitedwarf.html) indicates they should be written with lower case "d" (dA, dB, etc) but the existing concepts (DA, DB, etc) use uppercase D. Would the lowercase version be preferred?

[seweissman]

I think the upper case is preferred. The lowercase "d" is historical usage.

Although when talking about subdwarves as in "sdB" you do use the lowercase, so this is far from consistent.

[katieefrey]

new white dwarf types added