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\input{preface}
\chapter{Using outflows to track star formation in the W5 HII region complex}
\label{ch:w5}
\section{Preface}
Only a few months after arriving at CU, I was given the opportunity to visit
the peak of Mauna Kea to perform observations with the JCMT. I spend about 3
weeks at the telescope over the course of two years primarily mapping the W5
complex. A side-project done during these observations resulted in my Comps II
project on IRAS 05358+3543. These data were taken using Jonathan Williams'
Hawaii time allocation with the HARP receiver. The data were taken with
essentially no plan for how they would be used. The paper may have diminished
our group's overall interest in the W5 region: it turns out that star formation
is probably at its end here, being quenched by massive-star feedback. However,
there is a largely ignored cloud to the northwest of the well-studied W5 bubbles
that has significant potential to form new stars.
The W5 study was originally intended to include a Bolocam census of cores, but
the data in this region turned out to be the most problematic and contained
little signal. We acquired additional data in 2009, but never got around to
performing a joint analysis of the CO and continuum data. In part, at least,
this is because W5 is so faint in the millimeter continuum compared to many
Galactic Plane sources.
% This work is essentially a very detailed study of a star-forming region with
% minimal implications for star forming theories at the moment.
\section{Introduction}
Galactic-scale shocks such as spiral density waves promote the formation of
giant molecular clouds (GMCs) where massive stars, star clusters, and OB
associations form. The massive stars in such groups can either disrupt the
surrounding medium or promote further star formation. While ionizing and soft
UV radiation, stellar winds, and eventually supernova explosions destroy clouds
in the immediate vicinity of massive stars, as the resulting bubbles age and
decelerate, they can also trigger further star formation. In the ``collect and
collapse'' scenario
\verb|\citep[e.g.][]{elmegreen:sequential:1977}|, gas swept-up by expanding bubbles
can collapse into new star-forming clouds. In the ``radiation-driven
implosion'' model \verb|\citep{bertoldi:cometary:1990,klein:implosion:1983}|,
pre-existing clouds may be compressed by photo-ablation pressure or by the
increased pressure as they are overrun by an expanding shell. In some
circumstances, forming stars are simply exposed as low-density gas is removed
by winds and radiation from massive stars. These processes may play significant roles in
determining the efficiency of star formation in clustered environments
\verb|\citep{elmegreen1998}|.
% Shortly after igniting, young massive stars may either provide the additional
% pressure needed to collapse neighboring gas clumps into stars, or they may
% simply disperse and destroy their natal environments. The former phenomenon,
% known as triggered star formation, may play a significant role in determining
% the efficiency of star formation in clustered environments
% \verb|\citet{elmegreen1998}|. In addition, triggering from external processes
% asynchronous with star formation by direct collapse (e.g. supernovae, spiral
% density waves) are thought to be partly responsible for the evenutal collapse
% of parent molecular clouds, but it is not yet known on what scales triggering
% is important, nor how strongly each mechanism contributes.
Feedback from low mass stars may also control the shape of the stellar initial
mass function in clusters \verb|\citep{adams1996,Peters2010}|. Low mass young stars
generate high velocity, collimated outflows that contribute to the turbulent
support of a gas clump, preventing the clump from forming stars long enough
that it is eventually blown away by massive star feedback. It is therefore
important to understand the strength of low-mass protostellar feedback relative
to other feedback mechanisms.
Outflows are a ubiquitous indicator of the presence of ongoing star formation
\verb|\citep{reipurth2001}|. CO outflows are an indicator of ongoing embedded star
formation at a younger stage than optical outflows because shielding from the
interstellar radiation field is required for CO to survive. Although Herbig-
Haro shocks and \hh\ knots reveal the locations of the highest-velocity
segments of these outflows, CO has typically been thought of as a
``calorimeter'' measuring the majority of the mass and momentum ejected from
protostars or swept up by the ejecta \verb|\citep{Bachiller1996}|.
%\subsection{W5}
The W5 star forming complex in the outer galaxy is a prime location to study
massive star formation and triggering. The bright-rimmed clouds in W5 have
been recognized as good candidates for ongoing triggering by a number of groups
\verb|\citep{lefloch:cometary:1997,thompson:searching:2004,karr:triggered:2003}|. The
clustering properties were analyzed by \verb|\citet{koenig:clustered:2008}| using
Spitzer infrared data, and a number of significant clusters were discovered.
The whole W5 complex may be a product of triggering, as it is located on one
side of the W4 chimney thought to be created by multiple supernovae during the
last $\sim$10 MYr \citep[][Figure \verb|\ref{fig:color_overview}|]
{oey:hierarchical:2005}.
Following \verb|\citet{koenig:clustered:2008}|, we adopt a distance to W5 of 2 kpc
based on the water-maser parallax distance to the neighboring W3(OH) region
\verb|\citep{Hachisuka2006}|. As with W3, the W5 cloud is substantially
($\approx1.5\times$) closer than its kinematic distance would suggest
($v_{LSR}(-40~\kms)\approx3$ kpc). Given this distance,
\verb|\citet{koenig:clustered:2008}| derived a total gas mass of 6.5\ee{4} \msun\ from
a 2 \um\ extinction map.
The W5 complex was mapped in the $^{12}$CO 1-0 emission line by the Five
College Radio Astronomy Observatory (FCRAO) using the SEQUOIA receiver array
\verb|\citep{heyer:ogs:1998}|. The same array was used to map W5 in the \thirteenco\
1-0 line (C. Brunt, private communication). Some early work searched for
outflows in W5 \verb|\citep{bretherton:unbiased:2002}|, but the low-resolution CO 1-0
data only revealed a few, and only one was published. The higher resolution
and sensitivity observations presented here reveal many additional outflows.
\begin{figure*}
% Generated by GIMP
\includegraphics[angle=90,width=5in]{figures_chw5/w345mos_brightened_labeled}
\caption{An overview of the W3/4/5 complex (also known as the ``Heart and
Soul Nebula'') in false color. Orange shows 8 \um\ emission from the Spitzer
and MSX satellites. Purple shows 21 cm continuum emission from the DRAO CGPS
\verb|\citep{Taylor2003:CGPS}|; the DSS R image was used to set the display opacity
of the 21 cm continuum as displayed (purely for aesthetic purposes). The
green shows JCMT \twelveco\ 3-2 along with FCRAO \twelveco\ 1-0 to fill in
gaps that were not observed with the JCMT. The image spans
$\sim7\arcdeg$ in galactic longitude. This overview image shows the
hypothesized interaction between the W4 superbubble and the W3 and W5
star-forming regions \verb|\citep{oey:hierarchical:2005}|.}
\label{fig:color_overview}
\end{figure*}
%\subsection{Neighboring Regions}
While W5 is thought to be associated with the W3/4/5 complex, there are other
infrared sources in the same part of the sky that are not obviously associated
with W5. Some of these have been noted to be in the outer arm (several kpc
behind W5) by \verb|\citet{Digel1996}| and \verb|\citet{Snell2002}|.
\par
\par In section 2, we present the new and archival data used in our study. In
section 3, we discuss the outflow detection process and compare outflow
detectability in W5 to that in Perseus. In section 4, we discuss the physical
properties of the outflows and their implications for star formation in the W5
complex. In section 5, we briefly describe the outer-arm outflows discovered.
\section{OBSERVATIONS}
\subsection{JCMT HARP CO 3-2}
CO J=3-2 345.79599 GHz data were acquired at the 15 m James Clerk Maxwell
Telescope (JCMT) using the HARP array on a series of observing runs in 2008.
On 2-4 January, 2008, $\sim$ 800 square arcminutes were mapped. During the
run, $\tau_{225}$, the zenith opacity at 225 GHz measured using the Caltech
Submillimeter Observator tipping radiometer, ranged from 0.1 to 0.4
($0.420$ \kms) flows exist in the W5 region. Note that the
histogram compares quantities that are not directly equivalent: the outflows in
\verb|\citet{curtis2010}| and our own data are measured out to the point at which the
outflow signal is lost, while the `region' velocities are full-width half-max
(FWHM) velocities.
Finally, we use the detectability of outflows in Perseus to inform our
expectations in W5. Since it appears that we can detect outflows from low-mass
protostars with sub-stellar to $\sim30L_\odot$ luminosities
at the distance of W5 and these objects should be the most numerous in a
standard initial mass function, the distribution of physical properties in W5
outflows should be similar to those in Perseus. However, because W5 is a
somewhat more massive cloud ($M_{W5}\approx 5 M_{Perseus}$ \footnote{$M_{W5}$
is estimated from \thirteenco. We also estimate the total molecular mass in W5 using
the X-factor and acquire $M_{W5}=5.0\ee{4}$ \msun, in agreement with
\verb|\citet{karr:triggered:2003}|, who estimated a molecular mass of 4.4\ee{4} from
\twelveco\ using the same X-factor. \verb|\citet{koenig:clustered:2008}| estimated a
total gas mass of 6.5\ee{4} from a 2MASS extinction map. The total molecular mass
in Perseus is $M_{Perseus} \sim 10^4$ \verb|\citep{bally-perseus2008}|}), we might expect the
high-end of the distribution to extend to higher values of outflow mass,
momentum, and energy. Since we will likely see clustered outflows confused
into a smaller number of distinct lobes, we expect a bias towards higher values
of the derived quantities but a lower detection rate.
\subsubsection{Velocity, Column Density, and Mass Measurements}
\label{sec:measurements}
Throughout this section, we assume that the CO
lines are optically thin and thermally excited. The measured properties
are presented in Table \verb|\ref{tab:outflows}|. These assumptions are
likely to be invalid, so we also discuss the consequences of applying `typical'
optical depth corrections to the derived quantities. Because we do
not measure optical depths and the optical depth correction for CO 3-2 is less
well quantified than for CO 1-0 \verb|\citep{curtis2010,Cabrit1990}|\footnote{In
\verb|\citet{curtis2010}|, this correction factor ranged from 1.8 to 14.3;
\verb|\citet{arce2010}| did not enumerate the optical depth correction they
used but it is typically around 7 \verb|\citep{Cabrit1990}|. }, we only present the
uncorrected measurements in Table \verb|\ref{tab:outflowsderived}|.
The outflow velocity ranges were measured by examining
both RA-velocity and Dec-velocity diagrams interactively using the STARLINK
GAIA data cube viewing tool. The velocity limits are set to include
all outflow emission that is distinguishable from the cloud (i.e. the velocity
at which outflow lobes dominate over the gaussian wing of the cloud
emission) down to zero emission. An outflow size \citep[or lobe size,
following ][]{curtis2010} was determined by integrating over the blue and red
velocity ranges and creating an elliptical aperture to include both peaks; the
position and size therefore have approximately beam-sized ($\approx18\arcsec$)
accuracy. The integrated outflow maps are shown as red and blue contours in
Figure \verb|\ref{fig:pv2b}|. The velocity center was computed by fitting a
gaussian to the FCRAO \thirteenco\ spectrum averaged over the elliptical
aperture.
\Figure{figures_chw5/WidthHistogram}
{Histogram of the outflow line widths. {\it Black lines}: histogram of the measured
outflow widths (half-width zero-intensity, measured from the fitted central
velocity of the cloud to the highest velocity with non-zero emission). {\it
Blue dashed lines}: outflow half-width zero-intensity (HWZI) for the outer arm (non-W5) sample.
{\it Solid red shaded}: The measured widths (HWHM) of the sub-regions as
tabulated in Table \verb|\ref{tab:regionspectra}|.
{\it Gray dotted}: Outflow $v_{max}$ (HWZI) values for Perseus
from \verb|\citet{curtis2010}|. }
{fig:widthhist}{0.5}{0}
The column density is estimated from \twelveco\ J=3-2 assuming local thermal
equilibrium (LTE) and optically thin emission using the equation
$ N(\hh) =
5.3\ee{18}\eta_{mb}^{-1} \int T_A^*(v) dv $ for $T_{ex}=20$ K.
The derivation is given in the Appendix.
The column density in the lobes is likely to be dominated by low-velocity gas
and therefore our dominant uncertainty may be missing low-velocity emission
rather than poor assumptions about the optical depth.
The scalar momentum and energy were computed from
\begin{equation}
p = M \frac{\sum T_A^*(v) (v-v_{c}) \Delta v}{ \sum T_A^*(v) \Delta v}
\end{equation}
\begin{equation}
E = \frac{M}{2} \frac{\sum T_A^*(v) (v-v_{c})^2 \Delta v}{ \sum T_A^*(v) \Delta v}
\end{equation}
where $v_c$ is the \thirteenco\ 1-0 centroid velocity. The same
assumptions used in determining column density are applied here.
We
estimate an outflow lifetime by taking half the distance between the red and
blue outflow centroids divided by the maximum measured velocity difference
($\Delta v_{max} = (v_{max,red}-v_{max,blue})/2$), $\tau_{flow} = L_{flow} / ( 2 \Delta
v_{max})$, where $L_{flow}$ refers to the length of the flow. This method
assumes that the outflow inclination is 45\arcdeg; if it is more parallel to
the plane of the sky, we overestimate the age, and vice-versa. The momentum
flux is then $\dot{P} = p / \tau$. Similarly, we compute a mass loss rate by
dividing the total outflow mass by the dynamical age, which yields what is
likely a lower limit on the mass loss rate (if the lifetime is underestimated,
the mass loss rate is overestimated, but the outflow mass is always a lower
limit because of optical depth and confusion effects).
The dynamical ages are highly suspect since the red and blue lobes are often
unresolved or barely resolved, and diffuse emission averaged with the lobe
emission can shift the centroid position. Additionally, it is not clear what
portion of the outflow corresponds to the centroid: the bow shock or the jet could both potentially
dominate the outflow emission. \verb|\citet{curtis2010}| discuss the many ways in
which the dynamical age can be in error.
Our mass loss rates are similar to those in Perseus \emph{without} correcting our
measurements for optical depth, while our outflow masses are an order of magnitude lower.
It therefore appears that our dynamical age estimates must be too low, since we have no
reason to expect protostars in W5 to be undergoing mass loss at a greater rate than those in
Perseus.
However, given more reliable
dynamical age estimates from higher resolution observations of shock tracers,
the mass loss rates could be corrected and compared to other star-forming
regions.
Because the emission was assumed to be optically thin, the mass, column,
energy, and momentum measurements we present are strictly lower limits. While
some authors have computed correction factors to \twelveco\ 1-0 optical depths
\verb|\citep[e.g.][]{Cabrit1990}|, the corrections are different for the 3-2
transition \verb|\citep[1.8 to 14.3,][]{curtis2010}|. Additionally, CO 3-2 may
require a correction for sub-thermal excitation because of its higher critical
density (the CO 3-2 critical density is 27 times higher than CO 1-0; see
Appendix \verb|\ref{appendix:dipole}| for modeling of this effect).
Additionally, most of the outflow mass is at the lowest distinguishable
velocities in typical outflows \verb|\citep[e.g.][]{arce2010}|. It is therefore
plausible that in the more turbulent W5 region, a greater fraction of the
outflow mass is blended (velocity confused) with the cloud and therefore not
included in mass, momentum, and energy measurements. This omission could be
greater than the underestimate due to poor opacity assumptions.
The total mass of the W5 outflows is $M_{tot}\approx1.5 \msun$,
substantially lower, even with an optical depth correction of $10\times$, than
the 163 \msun\ reported in Perseus \verb|\citep{arce2010}|. \verb|\citet{arce2010}| also include
a correction factor of 2.5 to account for higher temperatures in outflows and a
factor of 2 to account for emission blended with the cloud. The temperature
correction is inappropriate for CO 3-2 (see Appendix \verb|\ref{appendix:dipole}|,
Figure \verb|\ref{fig:approx}|), but the resulting total outflow mass in W5 with an
optical depth correction and a factor of 2 confusion correction is about 30
\msun. In order to make our measurements consistent with a mass of 160 \msun\ , a density
upper limit in the outflowing gas of $n(\hh) < 10^{3.5} \percc$ is required,
since a lower gas density results in greater mass for a given intensity (see
Appendix \verb|\ref{appendix:dipole}|, Figure \verb|\ref{fig:coradex}|). However, we
expect the total outflow mass in W5 to be greater than in Perseus because
of the greater cloud mass, implying that the density in the flows must be even
lower, or additional corrections are needed.
The total outflow momentum is $p_{tot}\approx10.9 \msun$ \kms, versus a quoted
517 \msun \kms\ in Perseus \verb|\citep{arce2010}|. \verb|\citet{arce2010}| included
inclination and dissociative shock corrections for the momentum measurements
on top of the correction factors already applied to the mass. If these
corrections are removed from the Perseus momentum total (except for optical depth,
which is variable in their data and therefore cannot be removed), the uncorrected outflow
momentum in Perseus would be about 74 \msun \kms. The W5 outflow momentum, if
corrected with a `typical' optical depth in the range 7-14, would match or exceed
this value. If an additional CO 3-2 excitation correction (in the range 1-20)
is applied, the W5 outflow momentum would significantly exceed that in Perseus.
Assuming a turbulent line width $\Delta v \sim 3$ \kms\ (approximately the
smallest FWHM line-width observed), the total turbulent momentum in the ambient
cloud is $p = M_{tot} \Delta v = 1.3\ee{5} \msun$ \kms, which is $\sim10^5$
times the measured outflow momentum - the outflows detected in our
survey cannot be the sole source of the observed turbulent line widths, even if
corrected for optical depth and missing mass.
Table \verb|\ref{tab:regionspectra}| presents the turbulent momentum for each
sub-region computed by multiplying the measured velocity width by the
integrated \thirteenco\ mass. Even if the outflow measurements are
orders of magnitude low because of optical depth, cloud blending, sub-thermal
excitation, and other missing-mass considerations, outflows contribute
negligibly to the total momentum of high velocity gas in W5. This result is
unsurprising, as there are many other likely sources of energy in the region
such as stellar wind bubbles and shock fronts between the ionized and molecular
gas. Additionally, in regions unaffected by feedback from the HII region (e.g.
W5NW), cloud-cloud collisions are a possible source of energy.
Figure \verb|\ref{fig:outflowhist}| displays the distribution of measured properties
and compares them to those derived in the COMPLETE \verb|\citep{arce2010}| and
\verb|\citet{curtis2010}| HARP CO 3-2 surveys of Perseus. Our derived masses are
substantially lower than those in \verb|\citet{arce2010}| even if corrected for
optical depth, but our momenta are similar to the CPOC (COMPLETE Perseus
Outflow Candidate) sample and our energies are higher, indicating a bias
towards detecting mass at high velocities. The bias is more heavily towards
high velocities than the CO 1-0 used in \verb|\citet{arce2010}|. The discrepancy
between our values and those of \verb|\citet{arce2010}| and \verb|\citet{curtis2010}| can be
partly accounted for by the optical depth correction applied in those works:
\thirteenco\ was used to correct for opacity at low velocities, where most of
the outflow mass is expected. Those works may also have been less affected by
blending because of the smaller cloud line widths in Perseus.
%\Figure{OutflowHistograms}{Histograms of outflow properties.}{fig:outflowhist}{1.0}
\FigureFour{figures_chw5/OutflowMassHistogram_legend}{figures_chw5/OutflowEnergyHistogram}{figures_chw5/OutflowMomentumHistogram}{figures_chw5/OutflowColumnHistogram}
{Histograms of outflow physical properties.
%All display a peak at low values in addition
%to a high excess. None are obviously well-fit by power-law or gaussian distributions.
The solid unfilled lines are the W5 outflows (this paper), the forward-slash
hashed lines show \verb|\citet{arce2010}| CPOCs , the dark gray
shaded region shows \verb|\citet{arce2010}| values for known outflows in Perseus, and
the light gray, backslash-hashed regions show \verb|\citet{curtis2010}| CO 3-2 outflow
properties. The outflow masses measured in Perseus are systematically higher
partly because both surveys corrected for line optical depth using \thirteenco.
The medians of the distributions are 0.017, 0.044, 0.33, and 0.14 \msun\ for
W5, Curtis, Arce Known, and Arce CPOCs respectively, which implies that an
optical depth and excitation correction factor of 2.5-20 would be required to
make the distributions agree (although W5, being a more massive region, might
be expected to have more massive and powerful outflows). It is likely that CO
3-2 is sub-thermally excited in outflows, and CO outflows may be destroyed by
UV radiation in the W5 complex while they easily survive in the lower-mass
Perseus region, which are other factors that could push the W5 mass
distribution lower.
}
{fig:outflowhist}
The momentum flux and mass loss rate are compared to the values derived in
Perseus by \verb|\citet{hatchell2007}| and \verb|\citet{curtis2010}| in Figures
\verb|\ref{fig:outflowPflux}| and \verb|\ref{fig:outflowmdot}|. Both of our values are
computed using the dynamical timescale $\tau_d$ measured from outflow lobe
separation, while the \verb|\citet{hatchell2007}| values are derived using a more
direct momentum-flux measurement in which the momentum flux contribution
of each pixel in the resolved outflow map is considered.
The derived
momentum fluxes (Figure \verb|\ref{fig:outflowPflux}|) are approximately consistent
with the \verb|\citet{curtis2010}| Perseus momentum fluxes; \verb|\citet{curtis2010}| measure
momentum fluxes in a range $1\ee{-6} -55$ \kms) and could be associated with different clouds within the
same spiral arm. The other 7 have central velocities $v_{LSR} < -55$ \kms\ and
are associated with the outer arm identified in previous surveys
\verb|\citep[e.g.][]{Digel1996}|. The properties of these outflows are given in Tables
\verb|\ref{tab:outeroutflows}| and \verb|\ref{tab:outeroutflowsderived}|; the distances listed are kinematic distances assuming
$R_0=8.4$ kpc and $v_0=254$~\kms\ \verb|\citep{Reid2009}|.
Of these outflows, all but one are within 2\arcmin\ of an IRAS point source.
Outflow 54 is the most distant in our survey at a kinematic distance $d=7.5$
kpc ($v_{lsr}=-75.6$ \kms) and galactocentric distance $D_G = 14.7$ kpc. It
has no known associations in the literature.
Outflows 41 - 44 are associated with a cloud at $v_{LSR}\sim -62$ \kms\ known
in the literature as LDN 1375 and associated with IRAS 02413+6037. Outflows 53
and 55 are at a similar velocity and associated with IRAS 02598+6008 and IRAS
02425+6000 respectively. All of these sources lie roughly on the periphery of
the W5 complex.
Outflows 45 - 52 are associated with a string of IRAS sources and HII regions
to the north of W5 and have velocities in the range $-55 < v_{LSR} < -45$.
They therefore could be in the Perseus arm but are clearly unassociated with
the W5 complex. Outflows 45 and 46 are associated with IRAS 02435+6144 and
they may also be associated with the Sharpless HII region Sh 2-194. Outflows
47 and 48 are associated with IRAS 02461+6147, also known as AFGL 5085.
Outflows 49 and 50 are nearby but not necessarily associated with IRAS
02475+6156, and may be associated with Sh 2-196. Outflows 51 and 52 are
associated with IRAS 02541+6208.
% \subsection{Comparison to other studies}
%
% XXXX: Use otherpapers compare.txt. Discuss what the most powerful outflows in each region
% would look like at 2kpc
% \Table{ccccc}{Comparison to other outflow surveys}
% {{Paper} & {Region} & {Tracer} & {Distance (pc)} & {Area (arcmin$^2$)} & {Area (pc$^2$)}
% & {Resolution (\arcsec)} & {Resolution (pc)} & {Outflows detected} \\ }
% {tab:surveys}
% {
% \verb|\citet{arce2010}| & CO 1-0 & Perseus & 250 & 57600 & 305 & 46 & 0.056 & 96 \\
% \verb|\citet{dionatos2010}| & CO 3-2 & Serpens & 310 & 29 & 0.24 & 14 & 0.021 & 20 \\
% \verb|\citet{davis:jcmt:2010}| & CO 3-2 & Taurus & 140 & 2705 & 4.5 & 14 & 0.0095 & 16 \\
% \verb|\citet{hatchell2007}| \tablenotemark{a} & CO 3-2 & Perseus & 250 & 204 & 1.1 & 14 & 0.017 & 37 \\
% This paper & CO 3-2 & W5 & 2000 & 7200 & 2440 & 14 & 0.14 & 38 \\
% }{
% \tablenotetext{a}{This survey targeted 51 mm cores, hence its much higher detection rate per unit area.}
% }
\section{Conclusions}
We have identified \nwfive\ molecular outflow candidates in the W5 star forming
region and an additional \nouter\ outflows spatially coincident but located in
the outer arm of the Galaxy.
\begin{itemize}
% \item The majority of the millimeter sources are associated with outflows,
% though some of the brightest millimeter sources lack outflows. These
% sources may consist of warmer dust that has not yet become Jeans
% unstable. Millimeter emission is a good tracer of active embedded star
% formation, while far-infrared brightness is not.
% \item The majority of the gas seen in \thirteenco\ and 1.1 mm emission is
% associated with star formation. There is therefore only a small amount
% of
\item The majority of the CO clouds in the W5 complex are forming stars.
Star formation is not limited to cloud edges around the HII region.
Because star formation activity is observed outside of the region of
influence of the W5 O-stars, it is apparent that direct triggering by
massive star feedback is not responsible for all of the star formation in
W5.
\item The W5 complex is seen nearly face-on as evidenced by a strict upper
limit on the CO column through the center of the HII-region bubbles. It
is therefore an excellent region to study massive star feedback and
revealed and triggered star formation.
\item Outflows contribute negligibly to the turbulent energy of molecular
clouds in the W5 complex. This result is unsurprising near an HII
region, but supports the idea that massive star forming regions are
qualitatively different from low-mass star-forming regions in which the
observed turbulence could be driven by outflow feedback. Even in regions
far separated from the O-stars, there is more turbulence and less energy
injection from outflows than in, e.g., Perseus.
\item Despite detecting a significant number of powerful outflows, the
total outflowing mass detected in this survey ($\sim 1.5$ \msun\ without
optical depth correction, perhaps $10-20$ \msun\ when optical depth is
considered) was somewhat smaller than in Perseus, a low to intermediate
mass star forming region with $\sim 1/6$ the molecular mass of W5.
\item The low mass measured may be partly because the CO 3-2 line is
sub-thermally excited in outflows. Therefore, while CO 3-2 is an
excellent tracer of outflows for detection, it does not serve as a
`calorimeter' in the same capacity as CO 1-0.
\item Even considering excitation and optical depth corrections, it is
likely that the mass of outflows in W5 is less than would be expected
from a simple extrapolation from Perseus based on cloud mass. CO is
likely to be photodissociated in the outflows when they reach the HII
region, accounting for the deficiency around the HII region edges.
However, in areas unaffected by the W5 O-stars such as W5NW, the
deficiency may be because the greater turbulence in the W5 clouds
suppresses star formation or hides outflows.
\item Velocity gradients across the tails of many cometary clouds have been
observed, hinting at their geometry and confirming that the outflows seen
from their heads must be generated by protostars within.
%The data presented contain tens of cometary clouds with
%precise kinematic information about their molecular gas.
\item Outflows have been detected in the Outer Arm at galactocentric
distances $\gtrsim12$ kpc. These represent some of the highest
galactocentric distance star forming regions discovered to date.
%\item Feedback in W5 is primarily destroying rather than
% triggering SF.
\end{itemize}
% \section{Acknowledgements}
% We thank the two anonymous referees for their assistance in refining this
% document. We thank Devin Silvia for a careful proofread of the text. This work
% has made use of the APLpy plotting package
% (\url{http://aplpy.sourceforge.net}), the pyregion package
% (\url{http://leejjoon.github.com/pyregion/}), the agpy code package
% (\url{http://code.google.com/p/agpy/}) , IPAC's Montage
% (\url{http://montage.ipac.caltech.edu/}), the DS9 visualization tool
% (\url{http://hea-www.harvard.edu/RD/ds9/}), the pyspeckit spectrosopic analysis
% toolkit (\url{http://pyspeckit.bitbucket.org}), and the STARLINK package
% (\url{http://starlink.jach.hawaii.edu/}). IRAS data was acquired through IRSA
% at IPAC (\url{http://irsa.ipac.caltech.edu/}). DRAO 21 cm data was acquired
% from the Canadian Astronomical Data Center
% (\url{http://cadcwww.hia.nrc.ca/cgps/}). The authors are supported by the
% National Science Foundation through NSF grant AST-0708403. This research has
% made use of the SIMBAD database, operated at CDS, Strasbourg, France
%{\it Facilities:} JCMT, VLA
%\bibliography{w5outflows}
{\tiny
\clearpage
\include{outflowtable_mnras} % tab:outflows
\include{outflowsumtable_mnras} % tab:outflowsums
\clearpage
\include{outerarm_outflowtable_mnras}
}
\include{individual_outflows_preface}
%\include{individual_outflows}
\include{w5_appendix}
%\end{document}
\input{solobib}
\end{document}