[CII] 158M Emission from L1630 in Orion B

Home , Horsehead Nebula, NGC 2023

[CII] 158 µm emission from L1630 in Orion B

Cornelia Pabst

Leiden Observatory

November 29, 2017

in collaboration with: J. R. Goicoechea, D. Teyssier, O. Berné,B. B. Ochsendorf, M. G. Wolfire, R. D. Higgins, D. Riquelme, C. Risacher, J. Pety, F. LePetit, E. Roueff, E. Bron, A. G. G. M. Tielens

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 Introduction

PhD student under supervision of Xander Tielens Leiden Observatory, Netherlands

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 1 / 30 [CII] 158 µm emission

[CII] ﬁne-structure line one of the brightest far-infrared cooling lines of the ISM, 1% of total FIR continuum ∼ [CII] line can be observed in distant galaxies correlation of SFR and [CII] intensity: [1] for 46 nearby galaxies, [2] on Galactic scale origin of [CII] emission: dense PDRs, cold HI gas, ionized gas, CO-dark gas on Galactic scale cf. GOT C+ [2] need to spatially resolve the ISM Orion molecular cloud as template region velocity-resolved mapping allows to form a 3D picture

[1] Herrera-Camus et al. (2015) ApJ 800:1, [2] Pineda et al. (2014) A&A 570:A121

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 2 / 30 The optical window

Image Credit: NASA/ESA/Hubble Heritage Team; M. Robberto/Hubble Space Telescope Orion Treasury Project Team

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 3 / 30 The infrared window

Left: visible light. Right: infrared light (IRAS). Image Credit: Akira Fujii/NASA/IRAS Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 4 / 30 L1630 in the Orion B molecular cloud - visible

Alnilam

Flame Nebula (NGC 2024)

Alnitak

NGC 2023

σ Ori Horsehead Nebula

IC 434

Image Credit: ESO, Digitized Sky Survey 2

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 5 / 30 L1630 in the Orion B molecular cloud - infrared

Flame Nebula (NGC 2024)

NGC 2023

σ Ori Horsehead Nebula

IC 434 Image Credit: NASA/JPL-Caltech (WISE) blue: 3.4 µm, cyan: 4.6 µm, green: 12 µm, red: 22 µm.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 6 / 30 L1630 in the Orion B molecular cloud

L1630, comprising the iconic Horsehead Nebula, is illuminated/evaporated by the star system σ Ori at 3 pc distance (G0 = 100). edge-on geometry with respect to the illuminating source distance from us is 390 pc [3] an area of 120 170 was observed in [CII] using upGREAT onboard× SOFIA in December 2015 4.2 hours of Director’s Discretionary Time beam size 15.900, spectral resolution 0.19 km s−1

[CII] line-integrated intensity of L1630 [3] Schaefer et al. (2016) ApJ 152:213

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 7 / 30 Knowledge vs. understanding

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 8 / 30 Comparison with other gas tracers

00 FIR 00 8 µm 00 CO (1-0) 00 00 00 0 0 9 0 2.0 15 15 15 50 50 50 8

3.0 ] 30 30 30

40 40 40 1

60 60 ] 60 ] − 1 40 30 1 40 30 40 30 sr

7 − −

80 80 80 1.5 2 sr sr

90 20 90 20 90 20 − 2 2 00 00 00

50 50 − 50 − 6 cm 30 30 30 0 0 0 1 cm cm

1.0 − 1

70 1 70 70 22 22 5 22 − − 60 60 60 1.0 erg s 7 erg s

erg s 4 − 3 2 Dec (J2000) Dec (J2000) Dec (J2000) − − [10 50 20 50 20 3 50 20

40 40 [10 40 00 00 00 [10 0)

0.3 − m 00 00 00 0 0 0 10 10 µ 10 0.5 FIR 30 30 8 30 40 40 2 40 I I 30 30 30

20 20 CO (1 ◦ ◦ ◦ I 2 30 2 30 2 30 20

− − 1 − 30 0.1 30 0 30 0.0 4104000 4102000 5h4100000 4004000 4104000 4102000 5h4100000 4004000 4104000 4102000 5h4100000 4004000 RA (J2000) RA (J2000) RA (J2000)

Far-infrared emission 8 µm emission traces CO emission traces (20-1000 µm) traces the UV field by fluo- the molecular gas the UV radiation field rescence of PAHs at deeper within the re-radiated by dust. the surface of a cloud. cloud [4].

[4] CO (1-0) data from Pety et al. (2017) A&A 599, A98

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 9 / 30 [CII] channel maps from 8 to 16 km/s, in steps of 0.5 km/s

Tmb [K] 30 8.0 km/s 8.5 km/s 9.0 km/s 9.5 km/s 10.0 km/s

0 10.5 km/s 11.0 km/s 11.5 km/s 12.0 km/s 12.5 km/s 13.0 km/s 00 00 0 20 00 00 0 Dec (J2000) 30 ◦ 2

− 13.5 km/s 14.0 km/s 14.5 km/s 15.0 km/s 15.5 km/s 16.0 km/s 4103000 5h4100000 RA (J2000)

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 10 / 30 [CII] line-integrated intensity and structures 00 00 By means of the channel 0 100 15 maps and comparison with 90 other data, we identify sev- eral regions: 80 PDR1

CO clumps ] 1

70 − 00

Horsehead PDR 30 0

60 km s · PDR1 22 HII

50 [K PDR2 Horsehead v

PDR 40 d PDR3 Dec (J2000) PDR2.5 mb 00 30 T 00 R PDR2.5 0 PDR3 30

◦ 20 CO clumps 2 PDR2 − CO-dark cloud CO-dark cloud 10 HII region 0 4104000 4102000 5h4100000 4004000 RA (J2000)

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 11 / 30 Spectra towards molecular cloud

20 Horsehead PDR2 south 20

10 10

0 0

PDR1 PDR3 20 15

[K] 10 10 mb 5 T 0 0 20 PDR2 CO-dark cloud 10

10 5

0 0

0 5 10 15 20 0 5 10 15 20 25 v [km/s] line widths < 5 km/s

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 12 / 30 Spectra towards HII region

1.5 HII region north HII region south 1.0 1.0 [K] 0.5

mb 0.5 T 0.0 0.0 0 5 10 15 20 0 5 10 15 20 25 v [km/s]

[CII] line is fainter and broader: 9 km/s (left) and 5 km/s (right) ∼ ∼ Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 13 / 30 Line cut through the molecular cloud 00 00

0 9

PAH 8 µm 15 8 Hα ] 7 1 100 − sr

[CII] 2

6 − 00 30 cm 0 CO 5 1 22 −

PACS 160 µm 4 erg s 3 Dec (J2000) − 3 [10

80 00 m µ 00 0 8

2 I 30 ◦ 2

− 1

0 4104000 4102000 5h4100000 4004000 . RA (J2000)

u 60 .

a IRAC 8 µm image

0 1.0 0.8 0.6 0.4 0.2 0.0 oﬀset [pc] PDR3↑ PDR2.5↑ PDR2↑ Horsehead↑ PDR We recognize the prototypical layered structure of a PDR.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 14 / 30 Correlation plot I[CII] vs. I8 µm ] 1 − sr 2 3 10 4 − − · cm 1 −

[erg s CO-dark cloud CO clumps [CII]

I Horsehead neck 4 1 10− · Horsehead PDR PDR1 PDR2 PDR3

3 3 2 1 10− 3 10− 1 10− · · 1 2 1 · I8 µm [erg s− cm− sr− ]

[CII] emission is well-correlated with PAH emission.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 15 / 30 Correlation plot I[CII] vs. IFIR ] 1 − sr 2 3 10 4 − − · cm 1 −

[erg s CO-dark cloud CO clumps [CII]

I Horsehead neck 4 1 10− · Horsehead PDR PDR1 PDR2 PDR3

3 2 2 1 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ]

Correlation of [CII] with FIR emission is not as good as with PAH emission.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 16 / 30 Correlation plot I[CII]/IFIR vs. IFIR

CO-dark cloud 2 3 10− CO clumps · Horsehead neck Horsehead PDR PDR1 PDR2 PDR3 FIR

/I 2 1 10− [CII]

I ·

3 10 3 − 3 2 2 1 · 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ]

[CII] cooling eﬃciency I[CII]/IFIR varies by a factor of 10 within the mapped area.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 17 / 30 Modelling the correlation plots

We built edge-on models based on [5] with FUV intensity G0 = 100 appropriate for σ Ori, AV,los and n determined from the data.

We determined the line-of-sight depth of the cloud AV,los from the dust optical depth τ160, i.e FIR continuum photometry.

We ﬁnd AV,los 5.0 mag in PDR1, AV,los 2.5 mag in PDR2, and ' ' AV,los 0.5 mag in the Horsehead PDR ' We determined the gas density n from the scale length of the line + cuts, assuming AV = 2 for the transition C /C/CO. We ﬁnd n 3 103 cm−3 in PDR 1 and 2, n 4 104 cm−3 in the Horsehead' PDR· ' ·

[5] Tielens&Hollenbach (1985), Wolﬁre et al. (2010), Hollenbach et al. (2012)

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 18 / 30 3 3 Model result for n = 3 10 cm− on physical scale ·

3 2 n = 3.0 10 cm− 140 · 100 T K 60 20

1 10− AV,los = 2.5 AV,los = 5.0 2 10−

3 10− IFIR 4 1 10− I[CII] −

sr 5 I /I 2 FIR 10− [CII] − ICO (1 0)

cm 6 −

1 10− − 7 10− erg s 8 10−

9 10−

10 10− 10 11 − 2.0 1.5 1.0 0.5 0.0 x [pc]

In a nutshell: Luke-warm surface layers, T 120 K, emitting in [CII] and FIR ' + Colder gas mainly emits in CO, transition C /C/CO at AV 2 ' Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 19 / 30 Correlation plot I[CII] vs. IFIR with models ] 1 − sr 2 3 10 4 − − · cm 1 −

[erg s CO-dark cloud CO clumps [CII]

I Horsehead neck 4 1 10− · Horsehead PDR PDR1 PDR2 PDR3

3 2 2 1 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ]

3 −3 Dotted line: n = 3.0 10 cm , AV,los = 2.5 mag. · 3 −3 Dashed line: n = 3.0 10 cm , AV,los = 5.0 mag ·

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 20 / 30 Correlation plot I[CII]/IFIR vs. IFIR with models

CO-dark cloud 2 3 10− CO clumps · Horsehead neck Horsehead PDR PDR1 PDR2 PDR3 FIR

/I 2 1 10− [CII]

I ·

3 10 3 − 3 2 2 1 · 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ]

3 −3 Dotted line: n = 3.0 10 cm , AV,los = 2.5 mag. · 3 −3 Increases peak ratio Dashed line: n = 3.0 10 cm , AV,los = 5.0 mag · ⇒ by a factor of 2!

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 21 / 30 We determine physical properties of the molecular cloud:

We detect one [13CII] line (left: averaged over 180 spectra, right: 3140 spectra):

1.0 Horsehead PDR PDR1+2 1.0 0.8 0.8 0.6 0.6 [K] 0.4 0.4 mb

T 0.2 0.2 0.0 0.0

0 25 50 75 0 25 50 75 1 v [km s− ] Due to averaging over some range of conditions, the [CII] optical depth and excitation temperature are not well-determined.

Guevara et al. (priv. comm., in prep.) report τ[CII] 2 in the Horsehead PDR from deep observations. For PDR1 and 2 we' infer the C+ column density from the dust optical depth, and the excitation temperature from single spectra.

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 22 / 30 We determine physical properties of the molecular cloud:

from line cuts we determine the gas density: n ' 3 · 103 cm−3 in PDR1 and 2 n ' 4 · 104 cm−3 in Horsehead PDR

from [CII] emission and NC+ (from τ160) we ﬁnd temperatures: T ' 90 K in PDR1 and 2

in Horsehead PDR for τ[CII] ' 2, T ' 60 K;

from rotational H2 lines: T ' 265 K [6] models predict T ' 140 K

[6] Habart et al. (2011) A&A 527:A122

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 23 / 30 We determine physical properties of the molecular cloud:

2 from τ160 we estimate the gas mass within the mapped area (210 arcsec ):

L1630 gas mass: 280 M

CO-emitting gas: 250 M

[CII]-emitting PDR surfaces: 20 M (about 8%)

total luminosity:

L[CII] ' 14 L

LFIR ' 1200 L ratio: ∼ 10−2 compare [CII] cooling eﬃciency in PDR surfaces: (1.1 ± 0.3) · 10−2

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 24 / 30 Photoelectric heating eﬃciency With the physical properties we derived we can compare with the theoretical heating eﬃciency by PAHs and very small grains: 1 10− In red is the theoretical curve as of [7]. Lower 5 data points

IC59 are also from [7]. Horsehead IC63 L1630 2 10− ζ Per Photoelectric heating eﬃciency determined ζ Oph Orion Bar from [CII] and [OI] γ Ara (Horsehead PDR, [8])

photoelectric heating eﬃciency cooling eﬃciency. NGC 2023 3 10− 101 102 103 104 105 γ [K1/2 cm3] Horsehead PDR: → γ ' 3 · 102 K1/2 cm−3, η ' (1.7 ± 0.4) · 10−2 PDR1: → γ ' 2 · 103 K1/2 cm−3, η ' (1.2 ± 0.3) · 10−2 [7] Bakes&Tielens (1994) ApJ 427:822, [8] Goicoechea et al. (2009) ApJ 699:L165

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 25 / 30 Summary

We used

comparison with various gas and dust tracers (e.g. FIR, 8 µm, CO emission) to determine the origin of [CII] emission channel maps to identify structures correlation plots to study the behavior of [CII] emission with other gas and dust tracers (FIR, 8 µm) PDR models to ﬁt the correlation plots line cuts to determine the gas density single spectra to determine the gas kinetic temperature

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 26 / 30 Conclusions

by velocity-resolved [CII] observations we can discern connected structures within the L1630 molecular cloud 95% of [CII] emission in the studied area come from the molecular cloud, mainly PDR surfaces 5% stem from HII region [CII] traces gas with little to no CO emission (cf. CO-dark gas) [CII] cooling eﬃciency is 10−2 ∼ our edge-on models are able to reproduce the correlations in [CII] and FIR emission models of photoelectric heating by PAHs and very small grains overestimate the heating eﬃciency we measure

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 27 / 30 A preview of Orion A

Pabst et al. (2017) A&A 606:A29; Goicoechea et al. (2015) ApJ 812:75

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 28 / 30 This is not the end...

[CII] line-integrated intensity of the Orion Nebula (M42) L1630

black box: ∼ 9h with HIFI/Herschel, ∼ 35min with GREAT/SOFIA

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 29 / 30 SOFIA in morning light, 2016-11-17

Thanks to all who have made this study possible. Special thanks to Erick Young. And the GREAT team.

C. H. M. Pabst, J. R. Goicoechea, D. Teyssier, O. Berné,B. B. Ochsendorf, M. G. Wolfire, R. D. Higgins, D. Riquelme, C. Risacher, J. Pety, F. LePetit, E. Roueff, E. Bron, A. G. G. M. Tielens

Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 30 / 30