J/A+A/551/A43 AFGL 2591 multi-wavelength maps (Johnston+, 2013)
The standard model of low-mass star formation applied to massive stars:
a multi-wavelength picture of AFGL 2591.
Johnston K.G., Shepherd D.S., Robitaille T.P., Wood K.
<Astron. Astrophys. 551, A43 (2013)>
=2013A&A...551A..43J 2013A&A...551A..43J
ADC_Keywords: H II regions; YSOs ; Stars, OB; Interferometry ; Carbon monoxide ;
Radio continuum
Keywords: radiative transfer - techniques: interferometric -
circumstellar matter - stars: formation - stars: massive -
ISM: jets and outflows
Abstract:
While it is currently unclear from a theoretical standpoint which
forces and processes dominate the formation of high-mass stars, and
hence determine the mode in which they form, much of the recent
observational evidence suggests that massive stars are born in a
similar manner to their low-mass counterparts.
This paper aims to investigate the hypothesis that the embedded
luminous star AFGL 2591-VLA 3 (2.3E+5L☉ at 3.33kpc) is forming
according to a scaled-up version of a low-mass star formation
scenario.
We present multi-configuration Very Large Array 3.6cm and 7mm, as
well as Combined Array for Research in Millimeter Astronomy C18O and
3mm continuum observations to investigate the morphology and
kinematics of the ionized gas, dust, and molecular gas around AFGL
2591. We also compare our results to ancillary Gemini North near-IR
images, and model the near-IR to sub-mm Spectral Energy distribution
(SED) and Two Micron All Sky Survey (2MASS) image profiles of AFGL
2591 using a Monte-Carlo dust continuum radiative transfer code.
The observed 3.6 cm images uncover for the first time that the central
powering source AFGL 2591-VLA 3 has a compact core plus collimated jet
morphology, extending 4000AU eastward from the central source with an
opening angle of <10° at this radius. However, at 7mm VLA 3 does
not show a jet morphology, but instead compact (< 500AU) emission,
some of which (<0.57mJy of 2.9mJy) is estimated to be from dust
emission. The spectral index of AFGL 2591-VLA 3 between 3.6cm and 7mm
was found to be between 0.4 and 0.5, similar to that of an ionized
wind. If the 3.6cm emission is modelled as an ionized jet, the jet
has almost enough momentum to drive the larger-scale flow. However,
assuming a shock efficiency of 10%, the momentum rate of the jet is
not sufficient to ionize itself via only shocks, and thus a
significant portion of the emission is instead likely created in a
photoionized wind. The C18O emission uncovers dense entrained material
in the outflow(s) from these young stars. The main features of the SED
and 2MASS images of AFGL 2591-VLA 3 are also reproduced by our model
dust geometry of a rotationally flattened envelope with and without a
disk.
The above results are consistent with a picture of massive star
formation similar to that seen for low-mass protostars. However,
within its envelope, AFGL 2591-VLA 3 contains at least four other
young stars, constituting a small cluster. Therefore it appears that
AFGL 2591-VLA 3 may be able to source its accreting material from a
shared gas reservoir while still exhibiting the phenomena expected
during the formation of low-mass stars.
Description:
FITS images corresponding to Figs. 5, 6, 9, 11, 12 and 13 in the above
paper. Figs. 5 and 6 are, respectively, 3.6 cm and 7mm continuum
images taken with the Very Large Array (VLA). Fig. 9 contains ∼2.8 and
2.7 mm continuum Combined Array for Research in Millimeter Astronomy
(CARMA) images. Figs. 11 and 12 display a CARMA {13}CO image cube, and
Fig. 13 presents a CARMA C{18}O image cube. Further details of the
observations which produced these images are given in Section 2 of the
paper. Note that the {13}CO observations are missing significant flux
on extended scales, and are therefore difficult to interpret.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
20 29 24.9 +40 11 21 AFGL 2591 = IRAS 20275+4001
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 126 6 List of FITS files
fits/* . 6 Individual FITS files
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See also:
J/A+A/475/549 : AFGL 2591 maps in CS, SO and HCN lines (Benz+, 2007)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 F4.2 arcsec/pix Scale Scale of the image
25- 28 I4 pix Nx Number of pixels along X-axis
29 A1 --- --- [x]
30- 33 I4 pix Ny Number of pixels along Y-axis
34 A1 --- --- [x]
35- 36 I2 --- Nz Number of slices (1 for images)
38- 81 A44 --- Title Title of the file
83- 94 A12 --- FileName Name of FITS file in subdirectory fits
96-126 A31 --- Remarks Additional informations: value of frequency,
or range of velocity for cubes
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Acknowledgements:
Katharine Johnston, johnston(at)mpia.de
(End) Katharine Johnston [MPIA, Heidelberg], Patricia Vannier [CDS] 11-Dec-2012