VOUnit for solar density or metallicity?

[Markus Demleitner]

Hi Norman,

On Wed, May 25, 2022 at 05:47:19PM +0100, Norman Gray wrote:
> So Sun was indeed left out of Table 2 both accidentally and on
> purpose.  I meant to leave it out, but also meant to raise on-list

:-)  For the record, I'd like to move further towards the on purpose
part on "Sun"...

> So this means I now have two suggestions:
> 
>   1. We decide that 'Sun' either is or isn't a 'known unit'.
>   2. We mark Sects. 2.7 and 2.8, and Tables 4--7 as 'informative'
>   rather than normative (but still make them consistent with Table
>   2).

...which means on (1), we go towards "it's not", mainly because for
real code it's a nightmare to guess that the conversion factor from
Sun to kg would be about 2e30, whereas it would be 1.4 from Sun to
km/m**3, 274 from Sun to m/s**2 (probably), 6.27e5 from Sun to m/s,
2.1e6 from Sun to s and so forth.

On (2): I'm always in favour of having as little normative material
as possible (rationale:
https://blog.g-vo.org/requirements-and-validators.html).  I have not
*really* tried to ensure we're not losing anything we must constrain
if we do (2), but it's plausible enough.

Thanks,

          Markus