The use of high brightness temperature sources to constrain the scale heights and distances of planetary nebulae

✍ Scribed by J.P Phillips

• Book ID: 104426456
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 451 KB
• Volume: 8
• Category: Article
• ISSN: 1384-1076
• DOI: 10.1016/s1384-1076(02)00201-4

✦ Synopsis

We have investigated the mean scale height kz (PNe)l of planetary nebulae (PNe) above the galactic plane using sources 0 having high 5 GHz brightness temperatures. Such PNe are least affected by interstellar extinction, and appear to be characterized by a consistent and invariant mean galactic latitude kbl. We are, as a result, able to determine that kz (PNe)l5(0.1160.02)k kpc, where k is a scaling factor which depends upon the statistical distances which are employed. 0

The uncertainty in k, and in the scale heights of main sequence stars, means that it is almost impossible to determine reliable progenitor spectral types. However, if one assumes that most of the sources arise from F-type progenitors, then it is possible to show that shorter statistical scales (such as that of Daub [ApJ 260 (1982) 612]) provide the most realistic distances to these nebulae.