Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stsci.edu/institute/conference/iausps13/presentations/Przybilla.pdf Äàòà èçìåíåíèÿ: Unknown Äàòà èíäåêñèðîâàíèÿ: Tue Feb 5 20:43:49 2013 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: mercury surface

CNO in Massive Stars
Norbert Przybilla
& Maria-Fernanda Nieva
Dr. Remeis-Observatory Bamberg
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Intro

Question
What information can massive stars in the solar neighbourhood provide on the solar CNO abundance problem? solar neighbourhood: d 4 0 0 pc as sociations: Sco-Cen Ori OB1 Per OB2 Lac OB1 Cas-Tau

+ field stars + Ori OB1 Ia-Id sample of Nieva & Simon-Diaz (2011)
Nieva & Przybilla (2012)
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Intro

Early B-type stars
· spectral type: B0 ­ B2 · LC V ­ III (ZAMS to TAMS) · masses: 8 ... 18 Mì
lifetime of up to few tens of Myr

· Teff: 18000 ... 32000 K · luminosity: 104 ... 105 Lì
· `easy` atmospheres: + radiative equilibrium + weak winds
hydrostatic photospheres

no diffusion - non-LTE

constraints on elemental abundances @ present day
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics
stellar analyses from interpretation of observation photometry, spectroscopy
· fundamental stellar parameter: L, M, R · atmospheric parameters: Teff, log g, , Y, Z, etc. · elemental abundances

quantitative spectroscopy via model atmospheres

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

(Restricted) NLTE Problem
·transfer equation

Non-Local Thermodynamic Equilibrium

·statistical equilibrium:

· radiative rates: non-local · collisional rates:
MgII: Przybilla et al. (2001)

local · excitation, ionization, charge exchange, dielectronic recombination, etc. model atoms
huge amounts of atomic data: OP/IRON Project & own
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Nieva & Przybilla (2008)

Model Atom Improvements

Diagnostics

· allow reliable reproduction of entire observed line spectra C II · absolute abundances · low 1-scatter · tested over wide range of stellar parameters

C III C IV
Sco
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

NLTE Diagnostics: Stellar Parameters
using robust analysis methodology & comprehensive model atoms
minimising systematics !

· ionization equilibria Teff/log g elements: e.g. He I/II, C II/III/IV, O I/II, Ne I/II, Si II/III/IV, Fe II/III Teff / Teff ~ 1...2% usually: 5...10% · Stark broadened hydrogen lines log g/Teff log g ~ 0.05...0.10 (cgs) usually: 0.2 · microturbulence, helium abundance, metallicity + other constraints, where available: SED's, near-IR, ... · abundances: log ~ 0.05...0.10 dex (1-stat.) log ~ 0.07...0.12 dex (1-sys.) usually: factor ~2 usually: ???

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

Iterative Stellar Parameter and Abundance Analysis
Nieva & Przybilla (2012)

· iteration until all observational constraints are matched
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

Simultaneous Establishment of Ionization Equilibria
Nieva & Przybilla (2012)

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

NLTE Diagnostics: Stellar Parameters
using robust analysis methodology & comprehensive model atoms
minimising systematics !

· ionization equilibria Teff/log g elements: e.g. He I/II, C II/III/IV, O I/II, Ne I/II, Si II/III/IV, Fe II/III Teff / Teff ~ 1...2% usually: 5...10% · Stark broadened hydrogen lines log g/Teff log g ~ 0.05...0.10 (cgs) usually: 0.2 · microturbulence, helium abundance, metallicity + other constraints, where available: SED's, near-IR, ... · abundances: log ~ 0.05...0.10 dex (1-stat.) log ~ 0.07...0.12 dex (1-sys.) usually: factor ~2 usually: ???

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

Test: SEDs

Nieva & Przybilla (2012)

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

Test: Spectroscopic vs. Hipparcos Distances
Nieva & Przybilla (2012)

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

Test: Abundance Trends
C

Nieva & Przybilla (2012)

N

O

Ne

Mg

Si

Fe
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Diagnostics

NLTE Diagnostics: Stellar Parameters
using robust analysis methodology & comprehensive model atoms
minimising systematics !

· ionization equilibria Teff/log g elements: e.g. He I/II, C II/III/IV, O I/II, Ne I/II, Si II/III/IV, Fe II/III Teff / Teff ~ 1...2% usually: 5...10% · Stark broadened hydrogen lines log g/Teff log g ~ 0.05...0.10 (cgs) usually: 0.2 · microturbulence, helium abundance, metallicity + other constraints, where available: SED's, near-IR, ... · abundances: log ~ 0.05...0.10 dex (1-stat.) log ~ 0.07...0.12 dex (1-sys.) usually: factor ~2 usually: ???

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Quantitative Spectroscopy without Systematics ...

Diagnostics

Nieva & Przybilla (2012)

· several 104 lines: ~30 elements, 60+ ionization stages · complete spectrum synthesis in visual (& near-IR) ~90% in NLTE

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


... Realisation of a Stellar Astrophysicists`s Dream

Diagnostics
Nieva & Przybilla (2012)

telluric lines

· several 104 lines: ~30 elements, 60+ ionization stages · complete spectrum synthesis in visual (& near-IR) ~90% in NLTE

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Stellar Evolution

Nuclear path of the CNO-cycles - Theory
diagnostic diagram: mass ratios N/C vs. N/O

initially CN-cyle:

, O const.

~ 3.0

· for solar CNO (Asplund et al. 2009)

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Stellar Evolution

Nuclear path of the CNO-cycles - Observation
Nieva & Przybilla (2012)

mixed

pristine

~ 4.6

· for massive star CNO
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


CNO in Massive Stars

Chemical composition of the solar neighborhood @ present day
1 ~ 0.05 dex C
Nieva & Przybilla (2012)

He

8.33±0.04

7.79±0.04

N

8.76±0.05

O

Ne

Mg

Si

Fe

Red: our work

black: OB stars literature

Chemical homogeneity X=0.715

Cosmic Abundance Standard Z=0.014
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012

Y=0.271


CNO in Massive Stars

Comparison with Sun and F&G Stars
· comparison with our data on early B stars

Nieva & Przybilla (2012)

present-day chemical composition of solar neighbourhood at odds with solar composition ­ carbon subtle signature!

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Chemical tagging of the Sun`s place of birth
Nieva & Przybilla (2012)

comparison of bulk solar composition, modified for effects of GCE with CAS & considering Galactic abundance gradients radial migration of Sun in Milky Way disk birthplace of Sun at Rg~5-6 kpc

CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012


Conclusions
What information can massive stars in the solar neighbourhood provide on the solar CNO abundance problem? · none · good agreement of 4.5 Gyr old solar photospheric/bulk NO with present-day NO in solar neighbourhood (like for most elements) · disagreement in C worse if prefering Caffau et al. (2010) over Asplund et al. (2009 )

· considering effects of Galactochemical evolution & Galactic abundance gradients chemical tagging of Sun`s place of birth radial migration of Sun in Milky Way disk birthplace of Sun at Rg~5-6 kpc · a lot on the origin of the Sun & its relation to its present surroundings
CNO in Massive Stars
IAU XXVIII GA SpS13 ­ 28.08.2012