application of x-ray plasma diagnostics to nova winds
DESCRIPTION
Talk presented by Jan-Uwe Ness (XMM-Newton Science Operations Centre) at the symposium "From atoms to stars: the impact of spectroscopy on astrophysics", Oxford, UK, 28-28 July 2011.TRANSCRIPT
(ESAC)
European Space Astronomy Centre
Jan-Uwe NessJan-Uwe NessXMM-Newton Science Operations CentreXMM-Newton Science Operations Centre
Application of X-ray PlasmaDiagnostics to Nova Winds
ChandraXMM-Newton
Swift
The RS Oph system Recurrent Nova with 6 recorded outbursts since 1898
Accreted
material:H-rich!
Nuclear burning ignites
outburst
WD
Accreted
material:H-rich!
Nuclear burning ignites
outburst
enough radiativeenergy is producedto drive a wind with
v ≈ 1500 km s-1
WD
Pseudo Stellar
AtmosphereNuclear burning
Photosphere
Radiatively driven expansion
brightest in optical -> discovery
equivalent toa stellarradiation zone
R=100x106km
after 1 day
WD
WD
Nuclear burning
Photosphere
Density drops, outer layers go optically thin
=> Radius of Photosphere recedes to inner, hotter, layers
Pseudo Stellar
Atmosphere
Pseudo Stellar
AtmosphereNuclear burning
Photosphere
=> fades in optical but Lbol constant
=> spectrum shifts to higher energies ...
WD
Pseudo Stellar
AtmosphereNuclear burning
Photosphere
.... until the peak of the spectrum reaches soft X-rays
--> direct observations of nuclear burning
Super-Soft-SourceX-ray spectrum
⇒ SSS phaseWD
Lbol=1038 erg/s
WD WD WD
Constant Bolometric Luminosity phaseConstant Bolometric Luminosity phase
optical UV X-ray
Novae are powered by nuclear burning
The pressure is not high enough on a WD
surface to produce any elements heavier
than Helium
The CNO cycle changes the relative
abundances of C, N, and O
If the nova ejecta show any other
anomalies in composition, then either
- WD material has been dredged up
- The companion is anomalous
SSS Emission from hot white dwarf
Shock withstellar wind
+ giant in Symbiotic Novae
+ MS star in Classical Novae
Osborne et al. (2011)
shock phase SSS phase nebular phase
Swift observations of RS Oph
optical
Osborne et al. (2008)
shock phase SSS phase nebular phase
Swift observations of RS Oph
Ch
an
dra
/XM
M
XM
M-N
ew
ton
Ch
an
dra
XM
M-N
ew
ton
----
--- -
----
Ch
an
dra
Ch
an
dra
Swift spectra
grating spectra
RS Oph: 13.8 days after outburst H-like ionsHe-like ionsother lines(FeXVII - FeXXV)
simultaneousChandra and XMMspectra
Ness & Jordan (2008) MNRAS 385, 1691
3-T APEC model reproducesthe observations
==>Assumption of collisional
equilibrium may not be too bad
proper EMD analysis
f G T
N
O NeSi
MgS
Fe
f G T
f G T
N
O
Ne
Mg Si
S
Fe
solarabundance
0.46 x solar
N high=>CNO-cycledmaterial
RS Oph secondary has [N/Fe]=0.9:(Pavlenko et al. 2008)
=> 20-40% of N fromoutburst or companion
Sample of M giants bySmith & Lambert (1985/86)
RS Oph secondary has [N/Fe]=0.9:(Pavlenko et al. 2008)
=> 20-40% of N fromoutburst or companion
Sample of M giants by Rich et al. (2007)
Mg, Si not produced in outburst=> must come from WD or companion
The companion in Symbiotic Novae is a giant star that has similar abundance ano- malies as those expected in nova ejecta The abundances for RS Oph appear more anomalous than for typical stars of the same spectral type as the companion We might be seeing WD material
=> too many heavy elements for SN Ia But: The companion in symbiotics is stripped off the outer layers, exposing layers with different abundances.
Summary