1. SOFIA Observations of Orion BN/KL with FORCAST
James M. De Buizer
SOFIA-USRA
J. D. Adams, E. E. Becklin, T. L. Herter, M. R. Morris,
R. Y. Shuping, W. D. Vacca, H. Zinnecker

2. Why observe Orion? “Obligation”
To determine which sources are internally heated and contribute to the luminosity of BN/KL
The long wavelengths of FORCAST offer more dust penetrating power
Since the discovery of the IR emission in Orion in by Becklin & Neugebauer (1967) and Kleinmann & Low (1967), this nearest region of massive star formation has been studied to try to determine what exactly is causing the bright IR emission. 2
Background Image:Spitzer

3. Resolution at 37.1um ~4” (best ever achieved)
The central ~3’ region of the Orion nebula was observed with FORCAST on SOFIA
Filters: 6.6, 7.7, 19.7, 31.5, and 37.1 microns
Resolution at 37.1um ~4” (best ever achieved)
Short exposure times: s 3
Background Image:Spitzer

4. Resolution at 37.1um ~4” (best ever achieved)
The central ~3’ region of the Orion nebula was observed with FORCAST on SOFIA
Filters: 6.6, 7.7, 19.7, 31.5, and 37.1 microns
Resolution at 37.1um ~4” (best ever achieved)
Short exposure times: s 4
Background Image:Spitzer

5. Resolution at 37.1um ~4” (best ever achieved)
The central ~3’ region of the Orion nebula was observed with FORCAST on SOFIA
Filters: 6.6, 7.7, 19.7, 31.5, and 37.1 microns
Resolution at 37.1um ~4” (best ever achieved)
Short exposure times: s
KAO 38 um
(Stacey et al. 1995) 5
Background Image:Spitzer

6. Resolution at 37.1um ~4” (best ever achieved)
The central ~3’ region of the Orion nebula was observed with FORCAST on SOFIA
Filters: 6.6, 7.7, 19.7, 31.5, and 37.1 microns
Resolution at 37.1um ~4” (best ever achieved)
Short exposure times: s
KAO 38 um
FORCAST FOV 3’
3x better resolution
(Stacey et al. 1995) 6
Background Image:Spitzer

7. Blue=7um Green=19um Red=37um
KAO 38 um
(Stacey et al. 1995)
Ney-Allen Region
Blue=7um Green=19um Red=37um
SOFIA
Ney-Allen
q1 D
OMC1S-IRS1
Trapezium
OMC1S-IRS2
LV1
Shuping et al. (2012) 7
Background Image:Spitzer

8. Ney-Allen Region Trapezium OMC1S-IRS1 LV1 OMC1S-IRS2 KAO 38 um
(Stacey et al. 1995)
Ney-Allen Region
Optical/Hubble
SOFIA
OMC1S-IRS1
Trapezium
OMC1S-IRS2
LV1
Shuping et al. (2012) 8
Background Image:Spitzer

9. Blue=19um Green=31um Red=37um
BN/KL Region
Blue=19um Green=31um Red=37um
KAO 38 um
(Stacey et al. 1995)
SOFIA BN
IRc3
IRc4
IRc2
Source I
De Buizer et al. (2012) 9
Background Image:Spitzer

10. 5” 10
De Buizer et al. (2012)

11. BN declines in
prominence at
longer l’s 5” 11
De Buizer et al. (2012)

12. BN declines in prominence at longer l’s IRc4 dominates at l >31um5” 12
De Buizer et al. (2012)

13. BN declines in prominence at longer l’s IRc4 dominates at l >31um
A previously
unidentified area
of emission is
apparent at
l >31um (SOF1)
IRc4 dominates
at l >31um 5” 13
De Buizer et al. (2012)

14. There is an SiO outflow centered near Source I
Plambeck et al. (2009)
Black contours: VLSR = 6.7 km s−1 14

15. SOF 1 is coincident with the outflow lobe
There is an SiO outflow centered near Source I
Plambeck et al. (2009)
SOF 1
SOFIA 37 um
Black contours: VLSR = 6.7 km s−1 15

16. Outflow indicators, water masers and HH objects, present
Plambeck et al. (2009) HH HH HH
Two HH objects, 152–228 and 152–229, lie at the tip of the flow; proper-motion measurements indicate that they are moving away from source I at 35–50 km s−1 (Doi
et al. 2002).
HH-objects: Doi et al. (2002)
Water masers: Gaume et al. 1998) 16

17. IRc13 and IRc14 appear to be HH objects
Plambeck et al. (2009)
SOFIA 19 um
IRc13
IRc14
Two HH objects, 152–228 and 152–229, lie at the tip of the flow; proper-motion measurements indicate that they are moving away from source I at 35–50 km s−1 (Doi
et al. 2002). 17

18. Like BN, IRc4 is a self-luminous source18
De Buizer et al. (2012)

19. Like BN, IRc4 is a self-luminous source
Lbol = 1.3x104 Lsun
Lbol = 2.1x104 Lsun 19
De Buizer et al. (2012)

20. Like BN, IRc4 is a self-luminous source
Lbol = 1.3x104 Lsun
IRc4 luminosity is too high to be caused by externally heating
BN+IRc4 account for ~40% of the ~105 Lsun of the BN/KL region
Some people believe that radio source I is THE heating source for the entire KL region. Calculating the heating of source I on IRc4 reveals that it encounters <3% of the luminosity of source I, and would only intercept <3x10^3 Lsun; and order of magnitude less than the value we derive.
Lbol = 2.1x104 Lsun 20
De Buizer et al. (2012)

21. Conclusions
SOFIA/FORCAST observed the central 3’ of the Orion Nebula with the highest resolution ever at 31 and 37 microns
BN is not prominent at wavelengths 31 microns or longer
IRc4 is likely a self-luminous source with a luminosity of about 1/4 the entire KL Nebula
A previously unidentified area of emission, prevalent at wavelengths >31 microns appears to be associated with the outflow cavity
We detect likely MIR emission from HH objects in the Orion outflow 21