H-alpha stacked images reveal
large numbers of PNe in the LMC
Warren Reid1,
Quentin Parker1,2
1Department of Physics, Macquarie University, Sydney Australia
2Anglo-Australian Observatory, Sydney Australia
Our new, deep, high resolution Hα and matching R-band UKST
multi-exposure stack of the central 25 sq. degrees of the LMC
promises to provide an unprecedented homogeneous sample of >1,000
new PNe. Our preliminary 2dF spectroscopy on the AAT has vindicated
our selection process and confirmed 136 new PNe and 50 emission-line
stars out of a sample of 263 candidate sources within an initial
2.5 sq. deg. area. To date approximately one third of the entire
LMC has been scanned for candidates (~7.5 sq. deg.). More than
750 new emission sources have been catalogued so far along with
independent re-identification of all known and possible PNe found
from other surveys.
Once our image analysis is complete, we plan comprehensive
spectroscopic follow-up of the whole sample, not only to
confirm our PN candidates but also to derive nebula temperatures
and densities which, with the aid of photoionization modeling,
will yield stellar parameters which are vital for constructing
H-R diagrams for these objects. A prime objective of the survey
is to produce a Luminosity Function which will be the most
accurate and comprehensive ever derived in terms of numbers,
magnitude range and evolutionary state; offering significant
new insights into the LMC's evolutionary history. The
observation and measurement of our newly discovered AGB
halos around 60% of these PN will also assist in determining
the initial- to final-mass ratios for this phase of stellar
evolution.