SOFIA FORCAST Images of the Bipolar Planetary Nebula M2-9

M.W.Werner1, J. Davis2, R. Sahai1, M. Morris3, L. Keller4, T. Herter5

1JPL, 2Caltech, 3UCLA, 4Ithaca College, 5Cornell University.

Compact Planetary Nebula are ideal initial targets for FORCAST:

•  Bright in the infrared – often too bright for Spitzer

• Infrared emission known to peak in the 30um region

•  Well matched in size to FORCAST 3.2 arcmin field of view

•  Werner, Morris and Sahai were awarded 4 hours of SOFIA time to observe four such targets:

•  NGC7027, M2-9, NGC6543, Frosty Leo 2

Minkowski 2-9 Classic bipolar nebula

• Previous work estimates L=2500 Lsun

  Stellar temperature 15000K

• Distance = 1.2 Kpc

• Observed with FORCAST in six bands:

6.6, 11.1, 19.7, 24.2, 33.6, 37.1um 6-to-10 min per filter

• Photometry done on SOFIA Science Center Level 3 data products

16””

3

SOFIA Images of M2-9 6.6 11.1 17.9

24.2 33.6 37.1

40”

Properties of Central Point Source

• FWHM = 3.5 to 4.7 arcsec, increasing with wavelength – not resolved • Luminosity = 760 Lsolar. IRAS measured 1100Lsolar

• Breadth of Spectral Energy Distribution indicates that we are seeing a disk rather than a thick spherical dust shell (Lykou et al, A+A , 2011)

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5

Log

Flux

(Jy)

Log Wavelength (Microns}

SOFIA Central 5” Radius

IRAS

SOFIA Photometry ( )of Central Source Compared to Lykou et al Disk

Model

Turning to the Lobes

Halpha+[NII] 24.2um [OIII] (2010) (2010)

•  Infrared emission comes from region comparable in size to that seen in the optical

• Lobes show structure and limb brightening in visible

•  Distribution smoother in the infrared, although some structure is seen

•  Difference in spatial resolution partly, not totally responsible for this

Turning to the Lobes

Halpha+[NII] 24.2um [OIII] (2010) (2010)

•  Infrared emission comes from region comparable in size to that seen in the optical

• Lobes show structure and limb brightening in visible

•  Distribution smoother in the infrared, although some structure is seen

•  Difference in spatial resolution partly, not totally responsible for this

Turning to the Lobes (2)

19.7

24.2

33.6

37.1

44” 2.000

2.500

3.000

3.500

4.000

1.000 1.250 1.500 1.750 Log

Flux

[mJy

]

Log Wavelength (Microns)

SED of 3.75”x3.75” areas centered 7.5, 11.25, 15” S of central source.

•  Color Temperature about 100K •  Assuming emission due to dust….

•  Particle size <0.1 um • Total dust mass in lobes 0.004 solar masses

Horizontal scans through lobes, 10” N. of central source

•  Profiles suggest lobes not uniformly filled with dust but modestly “limb brightened”

Modeling Lobe Structure Cross Section #4, 24.2um, convolved with

beam

0

20

40

60

80

100

120

0 0.2 0.4 0.6 0.8 1 1.2 1.4

p/R

n = .15

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

LOBE MODELLED AS THIN CYLINDRICAL SHELL

0

20

40

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120

LOBE MODELLED AS THIN, LARGELY EMPTY

CYLINDER

LOBE MODELLED AS UNIFORM ANNULAR CYLINDER WITH ONLY

DATA

Conclusions •  SOFIA images of M2-9 show not only a bright, compact central source but also emission from the lobes at 19.7um and beyond.

•  The central source is not resolved by SOFIA at any wavelength, with angular size less than about 5 arcsec •  The central source has a 5-40um luminosity of 760 solar luminosities, more than half the luminosity measured by IRAS •  The broad infrared SED of this source is more suggestive of emission from a disk than of emission from a spherical shell

•  The emission from the lobes extends +/- 20 arcsec from the center •  The infrared emission is confined EW to a region comparable in width to the optical lobes •  The emission can be attributed to a cylindrical distribution of dust within the lobes with a small central empty region but without extreme limb brightening as suggested by the optical images