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WD O atm Paper, Motivation is here - Coggle Diagram
WD O atm Paper
Back ground
80% He/H shell in atm
less than 2% for Other types
Only 2 O atm
18000K<t_eff<22000K
Hot DQ satrs
C dominate
Origin unclear
Speculation
2 WD merge
via AGP C shell under the He/H shell
O dominate (DS) WD
He dominate atm but O is second
After that C
t_eff = 12000 K
Composition related to pre WD but unknown
To help the research more data lead to motivation
Detect of J12..
Temp is unusial
t_eff> 20000K
form SDSS photometry
Ultraviolet Galaxy Evolution Explorer (GALEX)
This temp if H or He they should be bold but no
T_eff = 21600 K and Log g = 7.93 +/- 0.17
Typical for ~0.56 SolM
But not for O atm WD
By ugriz spectrometry
estimated log g solution
distance = 360 +- 50 pc
in accurate distance
more data with GAIA
Mass we have not until GAIA
Modelings and Causes
Single star evo theory
star 6<MN10.6 SolM
cause massive WD 1<M SolM
Has power to fuse carbon in core
violent pulse cause the He/H shell blow away
During pAGB
For minimum 5.5 SolM (lowet theoretical mass)
Process
C/O core -> O/Ne/Mg layer -> C/O/H/He envelop
off-center ignition - 0.3 SolM
Blocked by convective layer
If envelop removed somehow
result would be Ox/Neon WD
How possilbe
Late C-shell flash
strong mass loss
binary evo including 2 WD merge
Conclution
It is only one through all 32000 SDSS WD stars
Time series spectroscopy needed to know about companion
Motivation is here