From AGB Stars to Planetary Nebula
From AGB Stars to Planetary Nebula
From AGB Stars to Planetary Nebula
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<strong>From</strong> <strong>AGB</strong> <strong>Stars</strong> <strong>to</strong> <strong>Planetary</strong> <strong>Nebula</strong>Cats Eye <strong>Planetary</strong> <strong>Nebula</strong>: HSTFriday, April 29, 2011
<strong>AGB</strong> <strong>Stars</strong>NOAOFriday, April 29, 2011
H -> Hein convectiveregionDredge UpPrialnikFriday, April 29, 2011
<strong>AGB</strong> stars pulsingSchwarzchild &Harm (1967)Friday, April 29, 2011
The 9th CycleSchwarzchild & Harm (1967)Friday, April 29, 2011
Dredge-Ups• First dredge up: generation of convective zoneformation on Red Giant Branch (brings up gasprocessed by H burning)• Second dredge up: after the Helium burning ceases(CNO products from Hydrogen shell burning)• Third dredge up: during <strong>AGB</strong> pulses: stuff fromHelium burning and S-process (and maybe carbonburning for intermediate mass stars)Friday, April 29, 2011
Winds and SuperwindsFriday, April 29, 2011
Mira (the wonder) aka Omicron CetiThese pulsations are much more rapid than the thermal pulses(which take 10,000s of years)http://www.aavso.org/vsots_miraFriday, April 29, 2011
The Mira variables are namedafter the pro<strong>to</strong>type Mira.Mira VariablesDiscovered as a variable in 1596.Mira is a 1.5 solar mass star in an<strong>AGB</strong> phase.Distance: 107 pcRadius: ~ 400 RsunLuminosity ~ 9000 Lsun.Periods 150 <strong>to</strong> 1000 daysMdot = 3 x 10 -7 Msun yr -1vw = 5 kms -1Mira Variables as a class are cool(3000 K), big 200-300 solarradii, and luminous: ~4000 Lsun.Often have spectral class M, S(zirconian oxides and C~O) or C(strong carbon linesFriday, April 29, 2011
Mira Variables and SunscreenLarge changes in visible brightness may be the result of TiO(sunblock) forming in the outer atmospheres.Reid & Golds<strong>to</strong>n 2002Friday, April 29, 2011
Friday, April 29, 2011
Mira’s bow shock and tail(Martin et al. 2007)4 pc long!Friday, April 29, 2011
Mira is a Binary(separation ~0.5”or ~50 AU)Friday, April 29, 2011
Friday, April 29, 2011A Jet from Mira
Friday, April 29, 2011OH/IR <strong>Stars</strong>
OH/IR <strong>Stars</strong>Engels: ESO MessengerFriday, April 29, 2011
Dust FormationHofner 2011Friday, April 29, 2011
OH/IR <strong>Stars</strong>Suh & Kim 2002Friday, April 29, 2011
Measuring Mass Loss from <strong>AGB</strong> <strong>Stars</strong>De Beck et al 2011Friday, April 29, 2011
Measuring Mass Loss from <strong>AGB</strong> <strong>Stars</strong>De Beck et al 2011Friday, April 29, 2011
Measuring Mass Loss from <strong>AGB</strong> <strong>Stars</strong>De Beck et al 2011Friday, April 29, 2011
<strong>Planetary</strong> <strong>Nebula</strong> are not spherically symmetric.The are often elliptical. They show jets and otherstructures. What causes this asymmetry?Friday, April 29, 2011
Fast and Slow WindsSlow wind 10 -4 - 10 -5 Msun yr -1V = 10 km s -1Fast wind 10 -7 - 10 -8 Msun yr -1V = 2000 km s -1Balick et al. 1987Friday, April 29, 2011
10 -7 Msun yr -1 ?FastWind10 -5 Msun yr -1Slow Superwindfrom ThermalPulsesFriday, April 29, 2011
Zijlstra 2006ESO MessengerFriday, April 29, 2011
547 nm606 nm658 nm673 nm953 nmThe Preplanetary <strong>Nebula</strong>AFGL 618WFC3 HSTFriday, April 29, 2011
Model for Preplanetary <strong>Nebula</strong>Fast windSlow superwind forming expanding disk?Friday, April 29, 2011
Molecular HydrogenEmission TowardAFGL 681Cox et al. 2003Friday, April 29, 2011
AFGL 618H2 LinesCox et al. 2003Friday, April 29, 2011
Friday, April 29, 2011The Pre-planetary <strong>Nebula</strong> AFGL 2688
AFGL 2688Cox et al. 2003Friday, April 29, 2011
Friday, April 29, 2011
SEDs of Preplanetary <strong>Nebula</strong>Monteiga et al. 2011Friday, April 29, 2011
Eventually, the hotinner white dwarf isuncovered, creating aplanetary nebula.Friday, April 29, 2011
Do All <strong>Stars</strong> Undergo a <strong>Planetary</strong> <strong>Nebula</strong> Phase?80% of <strong>Planetary</strong> <strong>Nebula</strong> are asymmetric.Asymmetric planetary nebula may be best explained by closebinaries.Fast jets may require close binary systems <strong>to</strong> launch them (MHDlaunching).Does this imply many stars do not form planetary nebula?Could planets play a role?De Marco 2011 and references thereinFriday, April 29, 2011
How do you get multiple jets from a binary?The Starfish Preplanetary <strong>Nebula</strong>OH/IR starSahai et al. 2005Friday, April 29, 2011
SummaryThe <strong>AGB</strong> phases are characterized by thermal pulses occurring on a 10,000-100,000year period.Mira variables are solar mass <strong>AGB</strong> stars showing pulsations on 300-1000 day periods.OH/IR stars are <strong>AGB</strong> stars showing OH masers in an expanding shells on strong IRemission due <strong>to</strong> dust formation in a shell. Most of their luminosity is radiated in theIR.<strong>AGB</strong> stars show mass loss rates from 10 -7 Msun yr -1 (wind) <strong>to</strong> 10 -4 Msun yr -1(superwind)<strong>Planetary</strong> nebula are not circularly symmetric, but are elliptical and often show jets.This asymmetry may be due <strong>to</strong> a faster, lower density wind, collimated by slowermaterial ejected equa<strong>to</strong>rial, magnetic fields, or possibly a binary (or planetary)companion.Preplanetary nebula are an intermediate stage between <strong>AGB</strong> stars and planetarynebulaThese sources still buried in a dense dust cloud (from dust formed in the wind), butshow multiple, collimated, low density jets. Sometimes the jets are rotated up <strong>to</strong> 90degrees from each other.Friday, April 29, 2011
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