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Grains and Gas in the Ejecta of Classical Novae. R. D. Gehrz Department of Astronomy, University of Minnesota. Outline. Novae and Galactic chemical evolution Outburst parameters from radio/IR data Physical properties of nova grains Comparisons with ISM and the Solar System Grains

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grains and gas in the ejecta of classical novae

Grains and Gas in the Ejecta of Classical Novae

R. D. Gehrz

Department of Astronomy, University of Minnesota

R. D. Gehrz

  • Novae and Galactic chemical evolution
  • Outburst parameters from radio/IR data
  • Physical properties of nova grains
  • Comparisons with ISM and the Solar System Grains
  • Gas Phase abundances
  • Summary

R. D. Gehrz

ir radio observations of classical novae collaborators

IR/Radio Observations of Classical Novae: Collaborators

University of Minnesota: R. D. Gehrz, T. J. Jones, T. Harrison, J. Lyke, C. G. Mason, E. P. Ney, M. Schuster, C. E.Woodward

Cornell University: T. Hayward, J. R. Houck, J. Miles

Caltech: K. Matthews, G. Neugebauer, K. Sellgren

University of Wyoming: G. Grasdalen, J. Hackwell

UK and Europe: M. Barlow, A. Evans, J. Krautter, A. Salama

Additional Collaborators: M. Greenhouse (GSFC), R. M. Hjellming (NRAO), S. G. Starrfield (AZ State), J. Truran (Chicago), R. E. Williams (STScI), A. F. Bentley (Eastern Montana), D. H. Wooden (NASA ARC), F. C. Witteborn (NASA ARC), S. A. Sandford (NASA ARC), L. J. Allamandola (NASA ARC), J. D. Bregman (NASA ARC), M. Klapisch (NRL)

R. D. Gehrz

ir radio development phases

IR/Radio Development Phases

  • The luminosity of the outburst fireball is Lo LEdd
  • c measures nH and the ejected ionized gas mass Mgas during the free-free expansion phase
  • Lo LEdd = LIR for optically thick dust shells  Lo = constant for a long time

Fireball Expansion Phase

Free-Free Expansion Phase

Coronal Phase in ONeMg Novae

Dust Cocoon Phase in CO Novae

 in m

R. D. Gehrz (1988, 1990)

R. D. Gehrz

physical parameters derivable from ir sed s and spectra

Physical Parameters Derivable from IR SED’s and Spectra

TBB in K and time of the outburst to in JD for expanding photospheres and dust shells

The apparent luminosity; for blackbodies, f = 1.36 ( f )max in W cm-2

The free-free self-absorption wavelength c in m

The outflow velocity Vo in Km s-1 from emission lines

R. D. Gehrz

mass of the ejecta from ir sed s

Mass of the Ejecta from IR SED’s

in M

From Thomson scattering, which dominates the shell opacity during the fireball/free-free transition:

From c during the optically thin free-free phase:

Mgas  1-3x10-4 M for ONeMg WD’s

Mgas  1-5x10-5 M for CO WD’s

in M

These methods are independent of D as long as Vo is known from IR spectra

R. D. Gehrz

ejected mass from modeling radio data

Ejected Mass from Modeling Radio Data

The data are best fit by a “Hubble flow” (V deceases linearly as a function of depth in the ejecta) in an optically thin free-free shell

This leads to a   r-3 density distribution from which a shell mass can be determined given D and V(r)

R. D. Gehrz

ejected gas mass determination from ir radio observations conclusions

Ejected Gas Mass Determination from IR/Radio Observations: Conclusions

Radio and IR observations give ejected masses of ionized gasthat are consistent with one another

These masses are lower limits to the true ejected mass

These lower limits are substantially larger than the ejected masses predicted by existing theoretical TNR models

The potential of Classical Novae for making significant contributions to ISM/Solar System abundances is therefore substantial and may have been underestimated

R. D. Gehrz

physical parameters from ir radio sed s light curves and direct imaging

Physical Parameters from IR/Radio SED’s, Light Curves, and Direct Imaging

in arcseconds

Angular radii of blackbody photospheres and shells:

Distance by blackbody and direct expansion parallaxes:

The luminosity of the WD central engine given D:

in kpc

in L

(Note that Lo LEdd )

R. D. Gehrz

SOFIA and Classical Nova Explosions

What can SOFIA tell us about the mineralogy of dust produced in

Classical Nova Explosions?

  • Stardust formation, mineralogy, and abundances
  • SOFIA’s spectral resolution and wavelength coverage is required to study amorphous, crystalline, and hydrocarbon components
  • Contributions to ISM clouds and the Primitive Solar System

QV Vul

QV Vul

R. D. Gehrz

dust condensation in co novae

Dust Condensation in CO Novae

Dust Formation in NQ Vul

  • Tc 1000 K
  • , where Vo is the
  • outflow velocity

Visual Transition

Lo LEdd = LIR

Tc = 1000K

R. D. Gehrz (1988, 1990)

R. D. Gehrz

nova grain properties

Nova Grain Properties

Novae produce carbon, SiC, silicates, and hydrocarbons

Abundances can be derived from visual opacity, IR opacity, and IR emission feature strength

The grains grow to radii of 0.2-0.7m

R. D. Gehrz

Amorphous Carbon Grains in the Ejecta of

NQ Vul, LW Ser, and V1668 Cyg

Gehrz 1988, ARA&A, 26, 377

Iron seems not to be an option

based on abundance arguments

Gehrz et al. 1984, ApJ, 281, 303

R. D. Gehrz

Carbon and SiC Grains in Nova 1370 Aql (1982)

Data from Gehrz et al. 1984, ApJ, 281, 303

R. D. Gehrz

Grain Condensation in V842 Cen (1986)
  • Amorphous Carbon
  • Hydrocarbons
  • Silicates

From R. D. Gehrz, 1990, in Physics of Classical Novae, eds. A. Cassatella and R. Viotti, Springer-Verlag: Berlin, p. 138.

R. D. Gehrz

grain condensation in nova qv vul 1987 1

Grain Condensation in Nova QV Vul 1987 (1)

Carbon, SiC, silicates, and hydro-carbons

were produced at different epochs

  • The fireball and dust shell expansion
  • rates show velocity gradients as large
  • as a factor of three

R. D. Gehrz

Grain Condensation in Nova QV Vul 1987 (2)
  • Carbon, Silicates, SiC, and PAH grains formed at different epochs
  • suggesting abundance gradients in the ejecta.
  • A. D. Scott (MNRAS, 313, 775-782 (2000)) has shown that this could
  • be explained by an asymmetric ejection due to a TNR on a rotating WD

R. D. Gehrz

Grain Condensation in V705 Cas (1993)
  • s

Free-free, amorphous carbon, silicates, and hydrocarbon UIR emission are required to fit the IR spectrum in detail.

There are many variables – constraining data are needed

R. D. Gehrz

Modeling the IR SED of V705 Cas (1993)

There are many variables – constraining data are needed

See C. Mason et al. 1998, ApJ, 494, 783

R. D. Gehrz

grain mass abundance and size

Grain Mass, Abundance, and Size

in M

Mdust from the infrared luminosity of the dust shell:

Abundance of the grain condensables is given by:

Grain radius from the optical depth of the visual transition and LIR:

compared to solar abundance

in m

(agr 0.2-0.7m)

R. D. Gehrz

Comets as the “Rosetta Stone”

of the Solar System

  • They are the remaining “planetesimals” from the epoch of planet formation in the primitive Solar nebula
  • The material released from comet nuclei during perihelion passage is therefore a sample of the content of this primordial environment
  • IR imaging photometry and spectroscopy can be used to deduce the composition and physical properties of the gas, dust, and ices present when the planets were forming

R. D. Gehrz

dust and gas in regions of star formation

Dust and Gas in Regions of Star Formation

  • The IR spectrum of W33A, a region of star formation, shows an abundance of features from grains, molecular gases, and ices in the 2-40 m spectral region
  • These materials are the building blocks of comet nuclei and can be identified in the IR emission spectra of comets

R. D. Gehrz

mineral dust and regions of star formation

Mineral Dust and Regions of Star Formation

"8-13 Micron Maps of the Trapezium Region of the Orion Nebula,"

R.D. Gehrz, J.A. Hackwell and J.R. Smith, 1975, Ap.J. (Letters), 202, L33.

R. D. Gehrz

SOFIA and Comets: Mineral Grains

What can SOFIA observations of comets tell us about the origin of the Solar System?

ISO Data

  • Comet dust mineralogy: amorphous, crystalline, and organic constituents
  • Comparisons with IDPs and meteorites
  • Comparisons with Stardust
  • Only SOFIA can make these observations near perihelion

Spitzer Data

The vertical lines mark features of crystalline

Mg-rich crystalline olivine (forsterite)

R. D. Gehrz

comet dust and nova dust compared

Comet Dust and Nova Dust Compared

agr  0.7m

agr  0.2m

Comet Hale-Bopp

r = 1.21 AU

 TBB = 253K

  • Both Comet dust and nova dust contain silicates and carbon
  • Comets have coma emission dominated by grains the size of those produced in nova outflows

R. D. Gehrz

novae and the primitive solar system interplanetary dust particles idps

Novae and the Primitive Solar System: Interplanetary Dust Particles (IDPs)

  • IDP’s are composed of sub micron grains within a “Cluster of Grapes” fractal structure tens to hundreds of microns across
  • IDP sub- grains are similar in structure, size, and composition to nova “stardust”
  • IDP’s have Carbon, Silicate, and hydrocarbon components seen in nova grains

R. D. Gehrz

sofia and comets protoplanetary disks

SOFIA and Comets: Protoplanetary Disks

What can SOFIA observations of comets tell us about the origins of our Solar System and other solar systems?

ISO Observations — Adapted from Crovisier et al. 1996, Science 275, 1904 and Malfait et al. 1998, A&A 332, 25

Image of Solar System IDP (Interplanetary Dust Particle)

Disk System

50 microns

ISO Data

Solar System Comet

  • The silicate features in HD 100546 and C/1995 O1Hale-Bopp are well-matched, suggesting that the grains in the stellar disk system and the small grains released from the comet nucleus are similar

R. D. Gehrz

SOFIA and Extra-Solar Circumstellar Disks

What can SOFIA tell us about circumstellar disks?

850 µm

JCMT beam

  • SOFIA imaging and spectroscopy can resolve disks to trace the evolution of the spatial distribution of the gaseous, solid, and icy gas and grain constituents
  • SOFIA can shed light on the process of planet formation by studying the temporal evolution of debris disks

53 µm


Debris disk around e Eridanae


beam sizes

R. D. Gehrz

How does the chemistry of disks vary with radius?
  • High spectral resolution can determine where species reside in the disk;
  • small radii produce double-peaked, wider lines.
  • Observing many sources at different ages in this way will trace the disk
  • chemical evolution

R. D. Gehrz

SOFIA and Comets: Gas Phase Constituents

What can SOFIA observations of comets tell us about the

origin of the Solar System?

C. E. Woodward et al. 2007, ApJ, 671, 1065

B. P. Bonev et al. 2007, ApJ, 661, L97


C/2003 K4


  • Production rates of water and other volatiles
  • Water H2 ortho/para (parallel/antiparallel) hydrogen spin isomer ratio gives the water formation temperature; a similar analysis can done on spin isomers of CH4
  • Only SOFIA can make these observations near perihelion

R. D. Gehrz

On the Nature of the Dust in the Debris Disk around HD 69830C. M. Lisse, C. A. Beichman, G. Bryden, and M. C. Wyatt The Astrophysical Journal, 658:584–592, 2007 March 20

Using a robust approach

to determine the bulk average mineralogical composition of the dust, we show it to be substantially different

from that found for comets 9P/Tempel 1 and C/ Hale-Bopp 1995 O1 or for the comet-dominated YSO HD 100546.Lacking in carbonaceous and ferrous materials but including small icy grains, the composition of the HD 69830 dust

most closely resembles that of a disrupted P- or D-type asteroid.

R. D. Gehrz

SOFIA and Classical Nova Explosions

What can SOFIA tell us about gas phase abundances in

Classical Nova Explosions?

  • Gas phase abundances of CNOMgNeAl
  • Contributions to ISM clouds and the primitive Solar System
  • Kinematics of the Ejection

R. D. Gehrz

Abundances from IR Forbidden Emission Lines

Greenhouse et al. 1988, AJ, 95, 172

Gehrz et al. 1985, ApJ, 298, L47

Hayward et al. 1996, ApJ, 469, 854

R. D. Gehrz

abundance anomalies in neon novae

Abundance Anomalies in “Neon” Novae

ONeMg TNR’s can produce and excavate isotopes of CNO, Ne, Na, Mg, Al, Si, Ca, Ar, and S, etc. that are expelled in their ejecta

ONeMg TNR’s are predicted to have highly enhanced 22Na and 26Al abundances in their outflows. These isotopes are implicated in the production of the 22Ne (Ne-E) and 26Mg abundance anomalies in Solar System meteoritic inclusions :

22Ne via: 22Na  22Ne + e + +  (1/2 = 2.7 yr)

26Mg via: 26Al  26Mg + e + +  (1/2 = 7105 yr)

R. D. Gehrz

classical novae and abundance anomalies

Classical Novae and Abundance Anomalies

  • Novae process  0.3% of the ISM
  • (dM/dt)novae 7x10-3 M yr-1
  • (dM/dt)supernovae 6x10-2 M yr-1

Gehrz, Truran, and Williams 1993 (PPIII, p. 75) and Gehrz, Truran, Williams, and Starrfield 1997 (PASP, 110, 3) have concluded that novae may affect ISM abundances:

Novae may be important on a global Galactic scale if they produce isotopic abundances that are  10 times SN and  100 times Solar; Ejected Masses calculated from IR/Radio methods give a lower limit

R. D. Gehrz

summary and conclusions

Summary and Conclusions

IR/Radio data yield quantitative estimates for physical parameters characterizing the nova outburst: D , Lo , Mgas , Tdust , adust , Mdust , Vo , Lo , grain composition, and elemental abundances

Nova ejecta produce all known types of astrophysical grains: amorphous carbon, SiC, hydrocarbons, and silicates

Classical Nova ejecta have large overabundances (factors of 10 to 100) of CNO, Ne, Mg, Al, S, Si

R. D. Gehrz

summary and conclusions pre solar clouds

Summary and Conclusions: Pre-Solar Clouds

IR/Radio data show that the mineral composition and size distribution of the “stardust” made by novae are similar to those of the small grains released by comets in the Solar System

IR/Radio data confirms theoretical predictions suggesting that nova TNRs can produce ejecta that lead to 22Ne (Ne-E) and 26Mg enhancements such as are seen in meteorites

Novae are therefore a potential source for at least some of the solids that were present in the primitive Solar Nebula

R. D. Gehrz

future research

Future Research

Physical parameters and abundances must be obtained for a larger sample of novae to improve statistics

Observations of stellar populations in M33 will be conducted using SIRTF to understand the global galactic contributions of classical novae

Further examination of IDPs and meteoritic inclusions should be made to identify pre-solar grains from novae

R. D. Gehrz