Analysis (1)

To obtain the metallicity of the nebula, we must measure key parameters such as the central star temperature and the distance.



Central Star Temperature:

    We must know this to determine the ionization state of the nebula.

Evidence that central star is hot (100,000 K):

  1. Presence of [Ne V]
  2. HeII 4686 to He I 5876 ratio
  3. Continuum visible in spectra
  4. possible coincidence with a ROSAT bright source (r= 17.46" +/- 17")
  5. Zanstra temperatures (H > 20,000, He> 60,000) - Indicates Case A

 
 

Distance:

    This is a lot tougher.  Distances to Galactic PN are notoriously inaccurate.

Using the Shlkovsky method (assuming the nebula has a standard mass), we
find distances between 11.5 and 23.5 kpc, depending on the assumptions made.
We also attempted to use a new distance indicator from Stanghellini et al. (2002)



but this fails for SBS1150+599.  The electron temperature of the nebula is
much higher than these objects, so a correction must be made.  Unfortunately, this
pushes the nebula mass to 2 solar masses, which is clearly ridiculous.

Regardless of the actual distance, the object is well out of the plane of the Galaxy, and is a halo object.

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