stellar'(and'planetary)'...
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Stellar'(and'planetary)'
archaeology'with'white'dwarfs'
Roberto'Raddi'
on'behalf'of'Boris'Gänsicke'
WEAVE'All'Hands'MeeBng'–'2016'December'19K21'−'Cambridge'
1.#White#dwarfs#
2.#Galac3c#&#stellar#archaeology#
3.#Evolved#planetary#system#
4.'CoreKcollapse'&'Ia'supernovae'
5.#Target#selec3on#
Outline'
95%#
5%#
Rwd#≈#0.01R!#≈#R⊕##
Mwd#≈#0.65#M!#
g#=#9.8#msI2'g#≈#106#msI2#'
Physical'parameters'
C/O#core#
Pure#H#or#He#atmosphere#
99%#
1%#
M0'
B2'
35Myr'
A0'
250Myr'
10Gyr'
Most#≈F0IB2#stars#ever#formed#are#now#faint#white#dwarfs##
CutKoff'at'faintest,'coolest,'oldest'
white'dwarfs'
bright'
'hot'
young'
White'Dwarf'Luminosity'FuncBon'
CutKoff'in'the'white'dwarf''
luminosity'funcBon'due'to'the'
limited'age'of'the'Galaxy'
Even'the'oldest'white'dwarfs'(9K11'
Gyrs)'are'sBll'visible'in'the'solar'
neighborhood'
faint'
cool'
old'
Larger'volumeKcomplete'sample'is'needed'
Subasavage'et'al.'2009,'AJ'137,'4547'
25pc'sample' Need#large,#deep,#homogenous#mul3Icolour#&#spectroscopic#surveys:##Gaia#+#WEAVE#
The'iniBalKmass'finalKmass'relaBon''
• 'ONe'core'• 'electronKcapture'SN'• 'coreKcollapse'SN'
Nomoto'1984,'ApJ'277,'791' SN'for'MMS>8.5(+1K1.5)'M!''
Smarf'et'al.'2009,'MNRAS'395,'1409'Dobbie'et'al.'2009,'MNRAS'395,'2248'
Stellar'archeology'
• Gaia'will'idenBfy'≈400,000'white'dwarfs'• 100%$complete$within$≈50pc,'50%'within'≈300pc'
• IniBalKfinal'mass'relaBon'!'galacBc'life'cycle'of'mafer'
• Luminosity'funcBon'of'thin/thick'disc'&'halo'
'''''''''''''''''''''''''''''''''''''''''!'star'formaBon'rate'history''
• Add'mainKsequence'star'counts'!'iniBal'mass'funcBon'
Need#temperatures,#masses,#and#radial#veloci3es##for#Gaia#WDs##
(see'e.g.'Torres'et'al.'2005,'MNRAS,'360,'1381;'Jordan'2007,'ASP'Conf.'Series,'372,'139)'
Spectroscopic'mass'measurements'
• ''Teff'and'log'g'from'filng''spectral'
'''models'to'the'Balmer'lines'
• ''Higher'Balmer'lines'essenBal'for''
'''accurate'log'g'(Kepler'et'al.'2006,''''
'''MNRAS'372,'1799)'
• ''EvoluBon'sequences'provide'the'''''cooling'age,'mass,'radius'
• ''Gaia'distances'will'improve'accuracy'
ObservaBonal'test'on'mass'radius'relaBon'
(Tremblay'et'al.'2016,'MNRAS,'in'press)'
Not'a'typical'white'dwarf''
CaII'
FeII'
MgII'
H'
Gänsicke et al. 2006, Science 314, 1908'
With'a'gaseous'metallic'debris'disc'
Target'selecBon:'Gaia'DR2'
#################Bp#I#Rp##################
absolute#GIm
ag####################
(see'e.g.'Torres'et'al.'2005,'MNRAS,'360,'1381;'Jordan'2007,'ASP'Conf.'Series,'372,'139)'
Gaia'WD'populaBon'G≤20'(GUMSK10)'
≈10K25'white'dwarfs'per'deg2'
+20◦#
I20◦#
per d
eg2!
FallKback'approach:'WD'probability'map'in''
reduced'proper'moBon'colour'space'
GenBleKFusillo'et'al.'2015,'2017'(in'prep);'Raddi'et'al.'2017,'in'prep'
SDSS,'PanSTARRS1,'(iZ)PTF,'DES'Surveys,'IPHAS/UVEX'
Conclusions'
####Gaia#will#iden3fy#a#few#100,000#white#dwarfs#" Accurate'massKdependent'luminosity'funcBon'as'tracer'of'galacBc'SFR'
" IniBalKtoKfinal'mass'relaBon'in'HD''
" Huge'resource'for'stellar,'binary'&'planetary'evoluBon'
''''Why#observe#~100,000#with#WEAVE?##" Sample'the'WD'cooling'sequence'as'f(M)'–'never'done'before'
" Sample'thick'disc'&'halo'populaBon'(~1%)'
" First'unbiased'sample'
" Rare'(few'%)'WDs'provide'important'link'to'supernovae,'planets,'gravitaBonal'waves'
sources'etc.'
Conclusions'
####Gaia#will#iden3fy#a#few#100,000#white#dwarfs#" Accurate'massKdependent'luminosity'funcBon'as'tracer'of'galacBc'SFR'
" IniBalKtoKfinal'mass'relaBon'in'HD''
" Huge'resource'for'stellar,'binary'&'planetary'evoluBon'
''''Gaia#followIup#requirements:#" Blue'coverage'down'to'≈'3700Å'!'accurate'Teff,'mass,'age'
" ResoluBon'λ/Δλ≈5000'!'measure'radial'velociBes'from'Hα'
''''WEAVE:'" ≈10K25'G≤20'white'dwarfs'per'square'degree'
" ≈1.5%'of'the'fibres'will'be'sufficient'to'observe'all'Gaia'white'dwarfs'" White'dwarfs'are'excellent'flux'/'telluric'calibrators'
A'wavelength'cutKoff'at'≈4000Å'would'result'in'
≈30%'of'all'white'dwarfs'having'mass'/'cooling'
age'uncertainBes'>'10%,'adding'substanBal'
noise'to'the'GAIA'white'dwarf'LMF!'
Higher'Balmer'lines'are'essenBal'for'
Mwd'&'τcool'
High'&'low'mass'WD'@'T=20000K'
Higher'Balmer'lines'are'essenBal'for'
Mwd'&'τcool'
HαKHε'(3800K6800Å)'
Hα'K'Hδ'(4000K6800Å)'
1100'white'dwarfs'from'SDSS''
High'&'low'mass'WD'@'T=20000K'
Not'a'typical'white'dwarf''
CaII'
FeII'
MgII'
H'
Gänsicke et al. 2006, Science 314, 1908'
A'gaseous'metallic'debris'disc'
CaII'
FeII'
MgII' !'
Horne'&'Marsh'(1986,'MNRAS'218,'761)'
H'
Gänsicke et al. 2006, Science 314, 1908'
Manser#et#al.#2016,#MNRAS#455,#4467#
Indirect'imaging'of''debris'discs''
around'white'dwarfs'
2003'
2014'
'Bme''
0.2R!#
2.0R!#
Koester'et'al.'2011,'A&A'530,'A114'
Cool'white'dwarfs:'planetary'archaeology'
Na' Ca'
Ca' Teff=5500K#Cooling#age##~#3Gyr!#Mg'
OneKinK20000:'An'OKNeKMgKSi'
atmosphere'
Kepler'et'al.'2016,'Science'352,'67'
Aborted#SNIa?#Failed#coreIcollapse?#
3x20min'sensiBve'to'massive'short'period'DDs'