Introduction
Planetary nebulae are crucial in returning
heavier metals into the interstellar
medium, influencing later star and galaxy
formation (Aller & Keyes, 87).
Criteria for Candidates
Altitude > 40°; Apparent Magnitude > 14;
Available Distance and Angular Radius;
Available Spectra
Knowledge Base
+
Probable chemical composition for
planetary nebula.
Chart is a template that was used to determine
spectral lines.
Pictures of Candidates and Spectra from Williams (from
top) NGC 7662; IC 1747; IC 289; M1-4; M2-2; NGC
7008; NGC 7534
Literature Review
Figure 1 Stratification of ions:
higher near core, lower farther
from star
-C. Szyka, JR Walsh et al determined the
highest ionization potential of planetary
nebula NGC 6302 by use of spectral analysis.
They also calculated temperature.
-K. Hermann et al determined the mass of
several planetary nebulae and found distance
using the luminosity function.
-B Webster studied emissions of magellanic
clouds as determined approximated distances.
Arnold, Jacob (2008)
Purpose
To find a correlation between mass and ionization potentials as well as to see
if mass affects elements expelled into interstellar medium
Project Goals
-Identify emission lines
-Identify ionization potentials
-Determine Density, Volume and Mass
Results
• Spectra reveal lighter chemical elements
 Most massive overall- Ar
• Significant direct correlation found between mass and highest
ionization potential value, r=0.944 and p=0.01 (Graph 1)
• Age (youngest to oldest) vs. average density: significant direct
inverse relationship, younger nebulae are more dense than older, r=0.926 and p=0.037 (Graph 2)
Discussion
• Goals: identify element, calculate ionization potentials/mass, find correlation,
relate to age and evolution
• supports findings of Harrington (1969), Szyszka et. al (2009)
• Direct correlation: more massive PN, greater value of highest ionization
potential
• Chemicals returned to interstellar medium lighter
 PNe and central stars same composition
 Future star formation- same present elements
• Relative ages determined: heavier elements found in older PNe due to nuclear
fusion over time
 Grouped and compared to average density, inverse relationship foundolder nebulae have lower densities due to less massive chemicals present
and ionized
Limitations
• Possible discrepancies in
identification of emission lines
Conclusion
• Mass and highest ionization potentials have correlation: greater mass
related to larger ionization potential values
• Less massive chemicals returned to interstellar medium and compose
central stars and PNe
• PNe relatively old in age
 only light elements present, nuclear fusion did not create
heavier elements yet
 older PNe, less dense
• Predict stellar evolution
Future Studies
• Harrington (1969)- temperature and
luminosities calculated from ionization
potentials, help place nebulae along H-R
diagram
• Relation to mass, density, age
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