Observations of unusual CO isotopologue abundances toward protostars

Rachel L. Smith Nature Research Center/North Carolina Museum of Natural Sciences

Appalachian State University

Klaus M. Pontoppidan Space Telescope Science InstituteGeoffrey A. BlakeCalifornia Institute of TechnologyAdwin C.A. BoogertNASA Herschel Science CenterAlexandra C. LockwoodCalifornia Institute of Technology

Workshop on Ice and Planet FormationLund Observatory, Lund, Sweden

15 May 2013

Monday, May 20, 13

Orion

Ophiuchus

Serpens

Corona Australis

CRIRES observations of CO isotopologues toward protostars enable precise study of carbon and oxygen isotopic reservoirs

1.2

1.0

0.8

0.6

0.4

0.2

4720470046804660

12C16O ice

P (3), P(4), P (5)12C16O

Serpens molecular cloud, d Sun ~ 230 pc

EC 90 (1)

EC 90 (0)

Portion of VLT-CRIRES spectrum toward embedded binary protostar EC 90

Flux

Wavelength (nm)

Monday, May 20, 13

1.2

1.1

1.0

0.9

0.8

0.7

235423522350234823462344

P(3)

P(2)

P(1)R(0)

EC 90 (S) EC 90 (N)

Partial CO overtoneEC 90

Wavelength (nm)

Flux

Binaries, VLT-CRIRES EC 90, Serpens

1.2

1.0

0.8

0.6

0.4

0.2

4720470046804660

EC 90

12C16O ice

P (3), P(4), P (5)12C16O

EC 90 (S)

EC 90 (N)

Partial fundamental CO band

Flux

Wavelength (nm)

Ciardi et al. 2005

N

S

Monday, May 20, 13

McKeegan et al. 2011

High-resolution astronomical observations can be used to investigate isotope anomalies in the solar system

!

" iO =

iO16O#

$ %

&

' (

iO16O#

$ %

&

' ( SMOW

)1

*

+ , ,

- , ,

.

/ , ,

0 , ,

x103

Monday, May 20, 13

McKeegan et al. 2011!

" iO =

iO16O#

$ %

&

' (

iO16O#

$ %

&

' ( SMOW

)1

*

+ , ,

- , ,

.

/ , ,

0 , ,

x103

CO self-

shie

ldin

g?

High-resolution astronomical observations can be used to investigate isotopologue-specific photodissociation in protostellar environments

Monday, May 20, 13

High- to medium-resolution observations are used to investigate 12CO and 13CO reservoirs in protostars

TexXt

Local ISM

Solar system

13C, primary and secondary origin

13C, secondary origin

After Prantzos et al. 1996

After Milam et al. 2005

Solar ~ 89

ISM ~ 70

Assumption: the solar system represents the

isotopic composition of the local ISM ~ 4.6 Gya

Implication: protostars observed today should

represent their parent clouds

Monday, May 20, 13

Precise abundances of CO isotopologues are calculated using high resolution near-IR spectroscopy

CRIRES instrument R ~ 95,000

VLT-CRIRES

Smith et al. 2009

Monday, May 20, 13

CRIRES instrument R ~ 95,000

CO line profiles are used to determine column densities

€

NJ =τοb 2πλο

mecπe2 f&

' (

)

* +

Smith et al. 2009

Precise abundances of CO isotopologues are calculated using high resolution near-IR spectroscopy

Monday, May 20, 13

€

NTot = N0 2J +1( )exp −hcBJ(J +1)kT

# $ %

& ' (

J

j∑

Smith et al. 2009

Precise abundances of CO isotopologues are calculated using high resolution near-IR spectroscopy

Monday, May 20, 13

Sample Rotational Analyses

Disk

Foreground cloud

Shared envelope?

40

35

30

806040200

EC 90 (1)

(black diamonds) (blue stars)

13 K

23 K

11 K17 K

17 K

22 K

E/k (K)

Ln(N

J/(2J

+1))

EC 90 (S) and EC 90 (N)

12C17O 12C18O13C16O

12C16O

Embedded core

Smith et al. 2009, Smith et al. in revision

Monday, May 20, 13

(cold)

(warm)

Best-derived 12CO/13CO abundance ratios from CRIRES sources

Smith et al. in revision

Monday, May 20, 13

0.6

0.5

0.4

0.3

0.2

0.1

0.0

1801601401201008060

IRS 44 ,Oph

V V CrA

RE50

LLN 19, Vela

V V CrA(S,N), Corona A.

DoAr24E(0,1), Oph

RNO 91, L 43

IRS 63 ,Oph

HL Tau, Taurus

RE 50, Orion

RNO 91, L 43

IRS 63 ,Oph

EC 90(0), Ser

EC 90(1), Ser

IRS 51, Oph

CO Ic

e Fr

actio

n

[ 12C16O]/[ 13C16O]Gas

[12C16

O] Ic

e/([12

C16O

] Ice

+ [12

C16O

] Gas

)

Total 12C16O ice vs 12CO/13COgas

Smith et al. in revision

Monday, May 20, 13

0.6

0.5

0.4

0.3

0.2

0.1

0.0

1801601401201008060

IRS 44 ,Oph

LLN 19, Vela

V V CrA(S), Corona A.

DoAr24E(0,1), Oph

EC 90(0), Ser

EC 90(1), Ser

IRS 51, Oph

CO Ic

e Fr

actio

n

[ 12C16O]/[ 13C16O]Gas

[12C16

O] Ic

e/([12

C16O

] Ice

+ [12

C16O

] Gas

)

Smith et al. in revision

Targets with only cold gas lines provide most precise

evaluation of potential 12CO-13CO gas-ice interaction

45

40

35

30

806040200

(black diamonds) (blue stars)

13 K

23 K

17 K

22 K

E/k (K)

Ln(N

J/(2J

+1))

EC 90 (S) and EC 90 (N)

13C16O

12C16O

Monday, May 20, 13

0.6

0.5

0.4

0.3

0.2

0.1

0.0

1801601401201008060

IRS 44 ,Oph

LLN 19, Vela

V V CrA(S), Corona A.

DoAr24E(0,1), Oph

EC 90(0), Ser

EC 90(1), Ser

IRS 51, Oph

CO Ic

e Fr

actio

n

[ 12C16O]/[ 13C16O]Gas

[12C16

O] Ic

e/([12

C16O

] Ice

+ [12

C16O

] Gas

)

Targets with only cold gas lines provide most precise

evaluation of potential 12CO-13CO gas-ice interaction

Suggested trend between cold gas

[12CO/13CO]gas and CO ice fraction

Smith et al. in revision

45

40

35

30

806040200

(black diamonds) (blue stars)

13 K

23 K

17 K

22 K

E/k (K)

Ln(N

J/(2J

+1))

EC 90 (S) and EC 90 (N)

13C16O

12C16O

Monday, May 20, 13

Oxygen isotopes1000

500

0

-500

-1000 10005000-500-1000

V V CrA (S)Corona AustralisTaurusOrionSerpensL 43OphiuchusStar-forming regions:EC90(1)

IRS 44

RNO 91

mass-dependentmass

-inde

pend

ent

18O/17O = 4.1

18O/17O = 3.5

Local ISM

IRS 63

HL Tau

V V CrA (N)

RE 50

δ18O'=103ln(18Ri/18RLocal ISM)

δ17 O

'=103 ln

(17R i

/17R L

ocal

ISM)

Smith et al. in revision; Smith et al. 2009

!

" iO =

iO16O#

$ %

&

' (

iO16O#

$ %

&

' ( SMOW

)1

*

+ , ,

- , ,

.

/ , ,

0 , ,

x103

Monday, May 20, 13

1000

500

0

-500

-1000 10005000-500-1000

V V CrA (S)Corona AustralisTaurusOrionSerpensL 43OphiuchusStar-forming regions:EC90(1)

IRS 44

RNO 91

mass-dependentmass

-inde

pend

ent

18O/17O = 4.1

18O/17O = 3.5

Local ISM

IRS 63

HL Tau

V V CrA (N)

RE 50

δ18O'=103ln(18Ri/18RLocal ISM)

δ17 O

'=103 ln

(17R i

/17R L

ocal

ISM)

Oxygen isotopes

Signature of CO isotopologue-specific

photodissociation

Smith et al. in revision; Smith et al. 2009

!

" iO =

iO16O#

$ %

&

' (

iO16O#

$ %

&

' ( SMOW

)1

*

+ , ,

- , ,

.

/ , ,

0 , ,

x103

Monday, May 20, 13

Massive protostarsCO ice and gas in high-UV fields at greater dSun

80

60

40

20

4.694.684.67

Juggler Nebula, d Sun ~ 2 kpc

R (9)R (10)R (11)

Wavelength [µm]

Flux

R (13)R (12)

P (3)P (2)P (1)

13C16O

12C16O

Portion of KECK-NIRSPEC CO rovibrational spectrum toward massive protostar AFGL 2136

Keck-NIRSPEC

NIRSPECR~ 25,000

R(0)R(1)

P(1) P(2) P(3) ........

Smith et al., new data

Smith et al., new data

Monday, May 20, 13

Conclusions

Significant heterogeneity is observed in [12CO]/[13CO]gas toward a range of local protostellar environments

Weak isotopic signature indicates that interplay between CO ice and CO isotopic reservoirs could influence [12CO]/[13CO]gas

Signature of CO self-shielding in two disks

Binaries may trace isotopically similar gas environments

Embedded cores may trace varying chemical pathways within the same cloud and between clouds

Additional precise data for a range of protostellar evolutionary stages, dSun and RGC will help in further evaluation of CO gas and ice isotopic reservoirs

Monday, May 20, 13