Planetary nebula luminosity function: Difference between revisions

Revision as of 17:22, 14 August 2015

Latest revision as of 22:17, 27 March 2024

(17 intermediate revisions by 9 users not shown)

Line 1:

{{Short description|Astronomical function}}

'''Planetary nebula luminosity function''' ('''PNLF''') is a secondary<ref name="Ferrareseetal2000" /> [[standard candle|distance indicator]] used in [[astronomy]]. It makes use of the [[O III|[O&nbsp;III]]] λ5007 [[forbidden line]] found in all [[planetary nebula]] (PNe) which are members of the old stellar populations ([[Population II]]).<ref name="Ferrareseetal2000">{{harvnb|Ferrarese|Ford|Huchra|Kennicutt|2000}}</ref>

It workscan wellbe forused to determine distances to both [[spiral galaxy|spiral]] and [[elliptical galaxy|elliptical]] galaxies despite their completely different [[stellar populations]] and is part of the [[Extragalactic Distance Scale]].<ref name="=Schoenberneretal2007">{{harvnb|Schoenberner|Jacob|Steffen|Sandin|2007}}</ref>

== Procedure ==

To estimate theThe distance estimate to a galaxy using the PNLF onerequires mustdiscovery firstof locatesuch pointan sourcesobject withinin the target galaxy that areis visible at λ5007 but not when the entire spectrum is considered. These points are candidate PNe, however, there are three other types of objects that would also exhibit such an emission line that must be filtered out: [[HII region|HII&nbsp;regions]], [[supernova remnant]]s, and [[Lyα galaxy|Lyα galaxies]]. After the PNe are determined, to estimate a distance one must measure their monochromatic <nowiki>[O&nbsp;III]</nowiki> λ5007 fluxesluminosity. What remains is a statistical sample of

PNe. The observed luminosity function is then fitted to some standard law.<ref name="Ciardullo2004">{{harvnb|Ciardullo|2004}}</ref>

Line 9 ⟶ 10:

== Physics behind process ==

The PNLF method is unbiased by [[metallicity]]. This is because [[oxygen]] is a primary nebular coolant; any drop in its concentration raises the plasma’splasma's electron temperature and raises the amount of [[collisional excitation]]s per ion. This compensates for having a smaller number of emitting ions in the PNe resulting in little change in the λ5007 emissions . Consequently, a reduction in oxygen density only lowers the emergent <nowiki>[O&nbsp;III]</nowiki> λ5007 emission line fluxintensity by approximately the square root of the difference in abundance. At the same time, the PNe’sPNe's core responds to metallicity the opposite way. In the case where the metallicity of the progenitor star is smaller, then the PNe’sPNe's [[central star]] will be a bit more massive and its emergentilluminating ultraviolet flux will be a bit largergreater. This added energy almost precisely accounts for the decreased emissions of the PNe. Consequently, the total <nowiki>[O&nbsp;III]</nowiki> λ5007 fluxluminosity that is produced by a PNe is practically

uncorrelated to metallicity. This beneficial negation is in agreement with more precise models of PNe evolution. Only in extremely metal-poor PNe does the brightness of the PNLF cutoff dim by more than a small percentage.<ref name="Ciardullo2004" />

The relative independence of the PNLF cutoff with respect to population age is harder to understand. The [O&nbsp;III] 5007λ5007 flux of a PNe directly correlates to the brightness of its central star. Further, the brightness of its central star directly correlates to its mass. In a PNe,and the central star's mass directly varies in relation to its progenitor's mass. However, by observation, it is demonstrated that reduced brightness does not happen.<ref name="Ciardullo2004" />

== Notes ==

Line 23 ⟶ 24:

| first1 = Robin

| title = Distances from Planetary Nebulae

| journal = Eprint arXiv:astro-ph/0301279

<!-- Invited review at the International Workshop on "Stellar Candles for the Extragalactic Distance Scale", held in Concepcion, Chile -->

| pages = 1279

| date = January 2003

| arxiv = astro-ph/0301279 |bibcode = 2003astro.ph..1279C }}

|arxiv = astro-ph/0301279 }}

* {{citation

| last1 = Ciardullo

| first1 = Robin

| title = The Planetary Nebula Luminosity Function

| journal = Eprint arXiv:astro-ph/0407290

| pages = 7290

| date = July 2004

| arxiv = astro-ph/0407290 |bibcode = 2004astro.ph..7290C }}

|arxiv = astro-ph/0407290 }}

* {{citation

| last1 = Ferrarese

Line 48 ⟶ 43:

| first3 = John

| last4 = Kennicutt

| first4 = Robert C., Jr.

| last5 = Mould

| first5 = Jeremy R.

Line 89 ⟶ 84:

| first1 = George H.

| title = Planetary nebulae as standard candles. I - Evolutionary models

| journal = Astrophysical Journal, Part 1 (ISSN 0004-637X)

| date = April 1, 1989

| volume = 339

Line 107 ⟶ 101:

| last4 = Sandin

| first4 = C.

| title = The evolution of planetary nebulae IV. On the physics of the luminosity function

| journal = EprintAstronomy arXiv:0708.4292& Astrophysics

| date = August 2007

| volume =473

| issue = 2

2| pages =467467–484

| bibcode = 2007A&A...473..467S

| doi= 10.1051/0004-6361:20077437

| arxiv=0708.4292

| s2cid = 56363650

}}

{{refend}}