Integral field spectroscopy of the Red Rectangle: Unraveling the carrier of the RRBs

in 2D.

Damian Kokkin, Robert Sharp, Masakazu Nakajima, and Timothy

Schmidt

The Red Rectangle

Central binary: 1915

Nebula: 1973

Distance: 330-710pc

Expelling carbon rich material

Rich optical spectrum

Cohen M., Winckel, H.V., Bond, W.E., Gull, T.R., AJ, 2004, 127, 2362

The Red Rectangle Bands

• Emission features close to DIB wavelengths

• Exhibit a steep blue edge with a red degraded tail

Sarre, Science 269, 1995

Are the DIBs and RRBs from the same carrier molecule?

Hi-res IFU spectra of Red Rectangle

2 nights observing at Very Large Telescope (Chile)28th-30th December 2004

5 telescope pointings

Integral field unit givesA spectrum per pixel

-Can chemically map the nebula!

The Red Rectangle bands and C2

T. W. Schmidt, D. L. Kokkin, S. H. Kable, R. G.

Sharp and R. Glinski (2006)

v=0

v=1

v=2

v=0

v=1

v=2

a3Pu

d3Pg

516nm 563nm

Swan bands first observed in 1802!

Described in 1857 by W. Swan

What we are actually seeing

C2 is seen in comets and other things

Extending C2 Observations on RR

• 27th and 28th December 2006

• Target band systems:– Swan origin and Δv =

+1

– Phillips (2,0)

– c-d origin

Observational Methodology

N

E

Observational Methodology

Band Night Arm Grating Range (Å) Resolution (Å) ExposureSwan 27th December Blue 2500V 5091-5458 0.366-0.411 10x30 min(0,0) 2006 5hrs

Swan 28th December Blue 2500V 4598-4993 0.391-0.43 10x30 min(1,0) 2006 5hrs

c-d 28th December Red 1000I 8541-9630 1.112-1.191 10x30 min(0,0) 2006 5hrs

Phillips 28th December Red 1000I 8541-9630 1.112-1.191 10x30 min(2,0) 2006 5hrs

RRBs 27th December

2006

Red 2000R 5620-6124 0.492-0.538 6x30min3hrs

Further Swan bands of C2 in the RR

C2 versus stellar emission

C2 Swan

origin

emission

Stellar

emission

Distance from object versus emission

1 5

10

More on the RRBs

RRBs with distance

1 5

10

Maps from the red arm

ERE

Emission

5800Å RRB

emission

Sodium

doublet

emission

5850Å RRB

emission

The ModelModeling: C2 Swan Origin

Assumes C2 is statistical equilibrium with the stellar radiation field.

Includes the 6 lowest electronic states and for each of these 0≤υ≤5 and 0≤J≤100 giving 8484

distinct ro-vibronic states for transtions to occur between.

Photophysics simulated by a Monte Carlo Markov chain starting in a random state.

Modeling: λ5800Å RRB and the C2 Swan Origin

The observed fluorescence on Earth

NW

F FTOTAL 23

7

)1026.206(4

10

237 )1026.206(410

TOTAL

FF

BN

10

2

230

7

1015.3

)1026.206(1610

e

mFfN TOTAL

F

At

5arcsec

If the oscillator strength of the λ5800Å RRB is 0.01 which is common for most medium to large PAH systems

and unity fluorescence yield then the abundance would be larger then C2. This approach the C2 column density

when f approaches unity.

Rate of any transition

Electronic Energy Levels

v=0

v=1

v=2

v=0

v=1

v=2

a3

Π u

d3

Πg

v=0

v=1

v=2

X1

Σg+

v=0

v=1

v=2

A1

Πu

Swan systemPhillips system

v=0

v=1

v=2

b3

Σg-

Ballik-Ramsay system

v=0

v=1

v=2

c3

Σu+

c-d system

X-a forbidden transitions

X-c forbidden transitions

Computational Methods

core

Valence active space

external

MOLPRO package

CASSCF reference states generated

aug-cc-pVxZ (x = D, T, Q, 5, 6)

Swan system used to validate calculations, then applied aV6Z to other systems:

Phillips, Ballik-Ramsay, c-d

MRCI: excitations into external space

Transition moments calculated by MOLPRO

Vibrational wavefunctions obtained from ab initio PESs to calculated state-

to-state f-values, Einstein coefficients & radiative lifetimes

Swan System - PES

D T Q 5 6

Swan System – Other Properties

c-d system

Radiative Lifetime: 4.72μsOscillator Strength:

0.0054

Direct observation of c-d system

• 1% premix of C2H2 in Ar

• DC Discharge

• Detection via LIF

v=0

v=1

v=2

v=0

v=1

v=2

a3Pu

d3Pg

v=0

v=1

v=2

v=3

c3

Σu+

High resolution

Kokkin, Reilly, Morris, Nakajima, Nauta, Kable, Schmidt, JCP, 125, 231101 (2006)

Conclusions

• Further C2 swan emission lines were detected

in the Red Rectangle.– C2 Swan origin and Δv = +1

– No detection of Phillips (2,0) and c-d origin

• Opens modelling opportunities of C2 in Red Rectangle.

• Characterise local environment• Physical properties of RRBs carrier

Acknowledgements

• Neil Reilly, Scott Kable, Klaas Nauta

• George Bacskay