Download Silvia Leurini (MPIfR), Friedrich Wyrowski (MPIfR), Fabrice Herpin

+
CHAMP /HIFI
maps of cluster-forming regions:
G327.3-0.6
Silvia Leurini (MPIfR), Friedrich Wyrowski (MPIfR), Fabrice Herpin (UNI Bordeaux), Floris van der Tak (SRON) + the WISH consortium
The WISH project and the study of the large scale environment of cluster–
forming regions:
To study the effects of clustered star formation and their associated outflows, the
WISH project (Water In Star-forming regions with Herschel, P.I. E. van Dishoeck)
includes a sub-program dedicated to the study of the large scale distribution of
selected H2O lines in six regions of active massive star formation with both HIFI
and PACS. Key questions for this sub-program are:
•What is the chemistry of the warm gas close to young high-mass stars in various
evolutionary stages, specifically the distribution of H2O? What is the relative
importance of shocks vs. UV?
•What are the kinematics of the warm gas?
•What are the effects of clustered star formation and feedback by protostellar
outflows on high-mass regions?
While we are still waiting for the execution of the large scale HIFI maps, the first
small scale HIFI maps have very recently been performed. Here, we present a
map of the 202-111 H2O transition centered on the hot core in G327.3. The region
mapped in H2O is indicated by the black box in Fig.1. The beam of the data is ~
23”
The southern region G327.3-0.6:
One of the most prominent regions of massive star formation in the southern
celestial hemisphere is the HII region G327.3–0.6 at a kinematical distance of 2.9
kpc (Bergman 1992). Associated with this region is a prominent hot core (500 M⊙
and 105 L⊙), characterized by H2O, OH, and CH3OH masers, and by a molecular
spectrum exceptionally rich in lines.
According to Wyrowski et al. (2006), the region G327.3–0.6 represents a
remarkable example of the complexity of massive star forming regions, since it
hosts different evolutionary phases of massive star formation:
– a bright HII region G327.3–0.5 to the north associated with a luminous PDR
seen in CO,
– an ultracompact HII region 2 arcmin (1.7 pc) south, seen in the cm continuum
and as bright MIR emission by GLIMPSE,
– 5–10 arcsec (0.07 – 0.14 pc) offset from the UC HII region, the hot molecular
core harboring several MIR point sources, and
– further east of the hot core, a dense and cold clump with an embedded
massive young stellar object, seen as an infrared dark cloud at mid-IR
wavelengths.
APEX complementary observations:
The Herschel observations of H2O are complemented by large scale maps of mid
J CO, and isotopologues, observations with the CHAMP+ array at the APEX
telescope (beam ~9”.5). The observations cover the CO (6-5) and (7-6) lines, and
the 13CO (6-5) and (8-7) transitions. Such data allow to derive the large scale
distribution of warm gas in the regions, since the CO abundance in warm gas is
quite stable.
Observations of NGC6334, W51E and G327.3 have been already performed.
G327.3-0.6 is also surrounded by two large scale infrared bubbles and two HII
regions, which Minier et al. (2009) suggested could have triggered star formation
in G327.3-0.6.
Figure 1:
Map of the CO(6-5) transition with an angular resolution of ~9”.5. The strongest emission
is found in the north and it is associated with the HII region G327.3–0.5 and a complex
of infrared sources. Line widths are ~10 kms-1, with typical velocities of -48 kms-1.
The hot core G327.3-0.6 (pos.3) is located in the south, and it is associated with a
secondary peak of CO emission. Line are a factor of 2 weaker, and show broad nonGaussian profiles. However, no clear bipolar red- blue-shifted emission, possibly
associated with outflows, is detected. The CO emission extends to the north-east,
towards the mid-IR dark cloud (pos. 1). The velocity of the13CO (6-5) line is -44 kms-1 (red
spectra in Fig. 2).
1
2
Spectra at Pos. 1
3
The H2O 202-111 (Eu~100 K) map is shown in red contours overlaid on the CO(6-5) map.
The region mapped is centered on the hot core. The peak of the H2O emission (pos. 2)
seems shifted from the hot core (pos.3), but this could be a result of the strong
absorption detected in the line. The line profile at the position of the hot core show non
Gaussian wings likely due to outflows, and self absorption at the source velocity (-44
kms-1). The line profile of the H2O 202-111 transition towards the hot core in G327.3-0.6 is
similar to that detected in the same transition by Marseille et al. (2010) in G31.41+0.31
and W43-MM1.
The emission is resolved and it extends towards the north-east (pos.1) as already seen
in CO.
Spectra at Pos. 2
Spectra at Pos. 3
Figure 2:
Spectra of CO (6-5), 13CO(6-5) and
H2O 202-111 towards positions 1, 2 and
3 (hot core) of Fig.1.
Bibliography:
Bergman et al. 1992, Ph.D. thesis
Marseille et al. 2010, A&A in print
Minier et al. 2009, A&A, 501, L1
Wyrowski et al. 2006, A&A, 454, L91