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The giant HII region NGC 3603

Bärbel Koribalski (ATNF)

In the News: "Tadpole hunters" may net forming planets

Papers:

``Australia Telescope Compact Array Radio Imaging of the Proplyd-like Objects in the Giant HII Region NGC 3603''
Mücke, A., Koribalski, B.S., Moffat, A.F.J., Corcoran, M.F., Stevens, I.R. 2002, ApJ 571, 366
``Galactic Starburst NGC 3603 from X-Rays to Radio''
Moffat, A.F.J., Corcoran, M.F., Stevens, I.R., Skalkowski, G., Marchenko, S.V., Mücke, A., Ptak, A., Koribalski, B.S., Brenneman, L., Mushotzky, R., Pittard, J.M., Pollock, A.M.T., Brandner, W. 2002, ApJ 573, 191
``The X-ray Reconvolution of NGC 3603''
Brenneman, L., Corcoran, M.F., Moffat, A.F.J., Marchenko, S.V., Ptak, A., Skalkowski, G., Mushotzky, R., Stevens, I.R., Mueke, A., Koribalski, B.S., et al. 2001, AAS 198, 9503
``Resolving X-ray Emission in the Galactic ``Starburst'' NGC 3603 with Chandra''
Corcoran, M.F., Moffat, A., Mushotzky, R., Stevens, I.R., Muecke, A., Skalkowski, G., Brandner, W., Koribalski, B., Marchenko, S., Ptak, A., Pollock, A.M.T., Koenigsberger, G. 2000, AAS 197, 3815
``Physical Properties of visual counterparts to X-ray sources in the giant HII region NGC 3603''
Brandner, W., Corcoran, M.F., Brandl, B., Chu, Y.-H., Grebel, E.K., Johnson, B., Koribalski, B., Marchenko, S., Muecke, A., Mushotzky, R., Moffat, A., Pittard, J., Pollock, A., Ptak, A., Skalkowski, G., Stevens, I. 2000, HEAD 32, 4207
``Resolving X-ray Emission in the Galactic ``Starburst'' NGC 3603 with Chandra''
Corcoran, M.F., Brandner, W., Johnson, B., Koribalski, B., Marchenko, S., Muecke, A., Mushotzky, R., Moffat, A., Pittard, J., Pollock, A., Ptak, A., Skalkowski, G., Stevens, I. 2000, HEAD 32, 4218

see also: recent NGC3603 papers in the literature

Other links:
ATCA radio imaging of the giant HII region NGC 3603
Anita Mücke (Universite de Montreal),
Bärbel Koribalski (ATNF),
A.F.J. Moffat (Universite de Montreal),
M.F. Corcoran (Goddard Space Flight Center),
I.R. Stevens (University of Birmingham)

Figure 1: 6 cm radio continuum emission of the HII region NGC 3603 (D = 6.1 kpc; 1' = 1.8 pc).
The image is dominated by a region approx. 2' x 2' in size, which contains the brightest and most complex structures. To the north of that is a fainter, extended area of emission, and to the west we find two "mushroom-like" structures. Also visible are the three known proplyds (see Paper I.) as well as at least one new proplyd (close to P3, see below). The brightest emission (red) comes from the heads of the gaseous pillars, well known from HST images. In general we find the radio continuum and the Halpha emission in remarkable agreement.
The image was made using `uniform weighting' of the data, comprising five 6-km arrays with a total of about 60 h integration time. The measured noise of about 0.4 mJy is a factor of 10 above the theoretical noise. The original beam of 1.64" x 1.32" has been convolved to 2".

Figure 1b: Zoom-in to the "mushroom-like" structures

Figure 2: Similar to Fig. 1, but extended structure has been filtered out (uvmin = 25 klambda), and a smaller region is shown.
Proplyd 4 is now clearly seen to the south-west of proplyd 3; it has an extent of about 6" !! There are possibly 1 or 2 more proplyds towards the south-east corner of the image. We also detected two stars in the cluster ! The r.m.s. noise varies across the image, but is close to 0.4 mJy/beam near the stars and proplyds. The emission near the pillars is not well cleaned, and a lot of the flux has been artificially broken up into numerous blobs. I keep trying.

Figure 3: 6 cm radio continuum image of proplyd 4.

ATCA Radio Imaging of the ProPlyD-like Objects in the Giant HII Region NGC 3603
Anita Mücke (Universite de Montreal),
Bärbel Koribalski (ATNF),
A.F.J. Moffat (Universite de Montreal),
M.F. Corcoran (Goddard Space Flight Center),
I.R. Stevens (University of Birmingham)

(2002) ApJ 571, 366

Abstract. Three cometary-shaped objects in the giant HII region NGC3603, originally found and identified as proto-planetary disks (ProPlyDs) by Brandner et al. 2000) using HST+VLT in the optical and near-infrared, have been detected with the Australia Telescope Compact Array (ATCA) in the radio continuum at 3 and 6 cm. All three ProPlyD-like objects are clearly resolved with an extent of a few arcseconds. The integrated 6 cm fluxes are up to 1.3 times higher than the 3 cm fluxes with spectral indices averaged over the whole clump between alpha=0.1 and -0.5 (S_nu ~ nu^alpha), indicating non-thermal emission for two of the three sources. We present spectral index maps, and show that the sites of negative radio spectral indices are predominantly concentrated in the direction of the tails in all three ProPlyD-like nebulae while positive spectral indices are found in the region facing the ionizing star cluster. In two of the three objects optically thin non-thermal (gyro-)synchrotron emission appears to dominate on average, while the average spectrum of the third source is in agreement with thermal bremsstrahlung or free-free absorbed gyrosynchrotron radiation. All measured fluxes are at least one order of magnitude higher than those predicted by Brandner et al. (2000). Upper limits for mass loss rates due to photo-evaporation are calculated to be 10^-5 Msun/year and for electron densities to be 10^4 cm^-3. Due to the unexpectedly large radio luminosities of the ProPlyD-like features a (proto-)stellar origin of the non-thermal emission from a dust enshrouded star appears unlikely. Instead we propose that magnetized regions within the envelope of the ProPlyD-like nebulae exist with a total emitting volume much smaller than the whole extent of the ProPlyD-like clump.
Headings: interstellar medium: HII regions: individual (NGC 3603) --- stars: pre-main-sequence --- stars: early type, interferometry --- stars: formation

Figure 1: Zoom-in of Figure 1 (see below) emphazising the ProPlyds 1 and 2.

Figure 2: ATCA 3-cm radio continuum emission (green contours) overlaid onto the HST image by Brandner et al. (2000). North is to the top and East to the left.

Figure 3: ATCA 3-cm radio continuum emission of the proplyds overlaid onto the HST image by Brandner et al. (2000).

Figure 4 and 5: HST (left) and VLT (right) images of NGC 3603. Please note that orientation of the images is different from those displayed above.
Related HST links:
NGC3603 Chandra project:
Corcoran, M.F., Moffat, A.F.J., Stevens, I.R. & the XMEGA group
NGC3603 ATCA project (C848):
Mücke, A., Koribalski, B., Moffat, A.F.J., Corcoran, M.F., Stevens, I.R.
>High resolution multifrequency observations of the stellar cluster in NGC3603
Proplyds in NGC3603:
Brandner et al. 2000 (AJ 119, 292)
Proplyds in Orion:
Doug Johnstone's Orion Nebula Research
A proplyd in G5.97-1.17:
Stecklum et al. 1998

Baerbel.Koribalski @ csiro.au

The giant HII region NGC 3603

ATCA radio imaging of the giant HII region NGC 3603

Figure 1: 6 cm radio continuum emission of the HII region NGC 3603 (D = 6.1 kpc; 1' = 1.8 pc).

Figure 1b: Zoom-in to the "mushroom-like" structures

Figure 2: Similar to Fig. 1, but extended structure has been filtered out (uvmin = 25 klambda), and a smaller region is shown.

Figure 3: 6 cm radio continuum image of proplyd 4.

ATCA Radio Imaging of the ProPlyD-like Objects in the Giant HII Region NGC 3603

(2002) ApJ 571, 366

Figure 1: Zoom-in of Figure 1 (see below) emphazising the ProPlyds 1 and 2.

Figure 2: ATCA 3-cm radio continuum emission (green contours) overlaid onto the HST image by Brandner et al. (2000). North is to the top and East to the left.

Figure 3: ATCA 3-cm radio continuum emission of the proplyds overlaid onto the HST image by Brandner et al. (2000).

Figure 4 and 5: HST (left) and VLT (right) images of NGC 3603. Please note that orientation of the images is different from those displayed above.