A Wind Analysis of an Evolved Giant

Phase Resolved FUSE and Phase Resolved FUSE and HST/STIS Observations of HST/STIS Observations of

an Eclipsing Symbiotic an Eclipsing Symbiotic Binary Binary

Cian Crowley Dr. Brian Espey Trinity College Dublin

Collaborators: McCandliss, Ferland, Lamers, Hauschildt, Barman, Keenan, Young

Cool Stars 13 - 2004 - Hamburg

What are symbiotic binaries?

Binary nature confirmed by IUEBinary nature confirmed by IUE

Red giant continuum with emission lines Red giant continuum with emission lines requiring photoionisation by UV sourcerequiring photoionisation by UV source

red giant primaryred giant primary white dwarf secondarywhite dwarf secondary

line emission line emission from ionised portion of RG windfrom ionised portion of RG wind

Closest separation detached binariesClosest separation detached binaries

Composite symbiotic spectrum

Need multiwavelength dataNeed multiwavelength data

System parameters

EG And has a number of important properties:EG And has a number of important properties:

Non-dusty, low extinction Non-dusty, low extinction

Low luminosity WD secondaryLow luminosity WD secondary

Bright from optical into far-UVBright from optical into far-UV

Eclipsing binaryEclipsing binary

Well determined orbit ~ 481 daysWell determined orbit ~ 481 days

Never observed to undergo outburstNever observed to undergo outburst

EG And…..some numbers:

SeparationSeparation ~ 4.5 R ~ 4.5 RRGRG

InclinationInclination > 70 > 70ºº (from eclipses) (from eclipses)

RG:RG: Spectral type: Spectral type: M3M3––

TTeff eff : : ~ 3,700K~ 3,700K

Luminosity: Luminosity: ~ 950L~ 950L

Mass loss Mass loss ~ few x 10~ few x 10–8 –8 MM yr yr–1–1

RRRGRG ~ 75 R ~ 75 R

WD:WD: TTeffeff ~ 75,000K ~ 75,000K

Luminosity Luminosity ~ 30L~ 30L

Dataset Ground-based high resolution echelle Ground-based high resolution echelle

spectra spectra (R ~ 35,000)(R ~ 35,000)

Far-Ultraviolet Spectroscopic Explorer Far-Ultraviolet Spectroscopic Explorer (FUSE) data for 912 – 1180 (FUSE) data for 912 – 1180 ÅÅngstrom region ngstrom region (R ~ 15,000 – 20,000)(R ~ 15,000 – 20,000)

Hubble Space Telescope (HST) medium Hubble Space Telescope (HST) medium resolution echelle spectra for 1150 – 3180 resolution echelle spectra for 1150 – 3180 ÅÅngstrom region ngstrom region (R ~ 48,000)(R ~ 48,000)

HST data covering 1150 – 5600 Å

Absorption lines in the UV / FUV

Incorrect or incomplete atomic data in FUV Incorrect or incomplete atomic data in FUV

Spectral region extremely feature richSpectral region extremely feature rich

But complications as always….

Absorption data provides tomographic Absorption data provides tomographic information on the chromosphere / low wind information on the chromosphere / low wind of the giant starof the giant star

HI columns well defined by Lyman alpha HI columns well defined by Lyman alpha damping profiledamping profile

– – blending and saturated lines complicate analysis blending and saturated lines complicate analysis

Observed wavelength

Flux

Phi=0.90 Phi=0.04 Phi=0.15Phi=0.80

Wind conditions Absorption lines from species such as Absorption lines from species such as CI, CII, NI, CI, CII, NI,

NII, OI, OII, MgII, AlII, SiII, PII, ArI, CaII, MnII, NII, OI, OII, MgII, AlII, SiII, PII, ArI, CaII, MnII, FeII, CoII, NiII….FeII, CoII, NiII….

Transitions observed from range of lower energy Transitions observed from range of lower energy levels: levels: absorption from 0 to 4.5ev above groundabsorption from 0 to 4.5ev above ground

However However nono CO or H CO or H22 absorption in chromosphere absorption in chromosphere

HH22/H/Htottot < 10 < 10–8–8

Populations of FeII levels reveal Populations of FeII levels reveal temp ~ 8,000Ktemp ~ 8,000K

Ionisation levelIonisation level constantconstant through ingress and egress through ingress and egress

Wind velocity profiles……

Standard wind model

The standard parameterisation of winds from The standard parameterisation of winds from both hot and cool stars is a beta law model:both hot and cool stars is a beta law model:

v(r) = v(1– R/r)

The following ranges of The following ranges of are found: are found:

0.5 0.5 1 hot stars (Lamers & Morton 1981) 1 hot stars (Lamers & Morton 1981)

2.5 2.5 3.5 K supergiants (Schroeder 1985) 3.5 K supergiants (Schroeder 1985)

Onset of ionisation

Observed column densities (red points) and smooth polynomial model fit (black line)

Determination of wind parameters

Data fit with a low order polynomial and this Data fit with a low order polynomial and this function is inverted function is inverted

Solving the velocity / column density equation Solving the velocity / column density equation is a form of Abel inverse problem to which a is a form of Abel inverse problem to which a solution has been found by solution has been found by Knill, Dgani and Knill, Dgani and Vogel (1993)Vogel (1993)

Hot stars

EG And

SY Mus

Further wind determinations…

The spectra show similarities to the EG And The spectra show similarities to the EG And data, but with stronger P-Cygni profilesdata, but with stronger P-Cygni profiles

We have additional new FUSE data for BF Cyg We have additional new FUSE data for BF Cyg (M5 (M5 IIIIII))

Clues to wind driving mechanism?Clues to wind driving mechanism?

Summary Determination of Determination of wind conditions and wind conditions and

accelerationacceleration for EG And for EG And

Stellar modelsStellar models being generated for giant being generated for giant

Further dataFurther data for other stars under analysis for other stars under analysis

Improved treatment of Improved treatment of absorption linesabsorption lines (including improved atomic data) underway(including improved atomic data) underway

Improved treatment of matter distribution Improved treatment of matter distribution ((hydro code + photoionisationhydro code + photoionisation) planned) planned

See poster:Brian Espey et al. : (Section F.1)

‘Multiwavelength observations of giant mass loss and interaction in eclipsing symbiotic binaries’

We acknowledge support from Enterprise Ireland Basic Research grant We acknowledge support from Enterprise Ireland Basic Research grant SC/2002/370 from EU funded NDPSC/2002/370 from EU funded NDP