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    {\small\rm\zihao{6}\songti\thepage\hfill
    \quad\quad ACTA ASTRONOMICA SINICA \hfill
    \hspace{2mm} Vol.44\vspace{2mm}}}} %%%%%%%
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    {\small\rm \zihao{6}\songti suppl.\hfill Y. Shi et al.: A Bipolar Molecular Outflow Near IRAS02461+6147  %%（作者：题目名称）
    \vspace{1.5mm}
    \hfill\thepage}}} %%%%%%%
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\zihao{5}\songti

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    \zihao{6}\songti
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    Vol.44~ Suppl.
    \hfill\hspace{8mm} %%% if ``October/January'' then \hspace{8/10 mm} July
    \small ACTA ASTRONOMICA SINICA
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      Feb.,~2003 \\[-1.5 true mm] %%January
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\vs\vs\vs \bc {\Large\bf\zihao{2}\heiti
A Bipolar Molecular Outflow Near IRAS02461+6147    %%（文题）
%\\[1ex]
%$\!\!^*$
}



\vs\vs{\normalsize\zihao{4}\fangsong Yong Shi\up{1},\hs\hs Yuefang
Wu\up{1},\hs\hs
 Martin Miller\up{2}\hs\&\hs  R. Qing Mao\up{3}}  %%（本文作者）

\vs
({\footnotesize 1~{\it Astronomy Department, CAS-PKU Joint Beijing Astrophysics
Center, Peking University, Beijing }~ 100871}) \\%%（本文作者单位）
 ({\footnotesize 2~ {\it Physical Institute, Kolon University, Germany}~ D-50937})\\
 (\footnotesize 3~ \pmo)

 %\vs
 \vs \ec

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\begin{quotation}

 \no{\bf A{\scriptsize\bf BSTRACT }}~~~\small
 A molecular outflow is discovered from the CO J=3-2 in
the region around 02$^{\rm h}$ 46$^{\rm m}$ 11.7$^{\rm s}$+61$^{\circ}$
47$^{'}$ 34.02$^{''}$ (1950), with three masers and an
ultra-compact (UC) H\,II region. The parameters of the outflow are
obtained. There is approximately 85$M_{\odot}$ of molecular
materials in the high velocity flow, and the mass loss rate is
$0.26\times{10^{-5}}M_{\odot}/$\,yr, while the energy transferred
reaches $3\times{10^{46}}$\,ergs. All above indicate that it is a
massive outflow and this region is a solitary massive star
formation (MSF) region. The mass of the central star and
the driving source of the outflow are discussed.

\vn
 \no{\bf Key words}~~  star: formation ---ISM: clouds, outflow
---ISM: kinematics and dynamics
\end{quotation}

%%%% 正文
 \vspace*{-4mm}\para{\large\bf{1}~~ Introduction}

\vspace{3.5mm}
 Molecular outflows indicate a remarkable early phase of
star formation\rf{1}. For a long time, works on the outflow
mechanism and accompanying accretion onto the star are based on
observations of low-mass object\rf{2,3}, while recently the focus
turns to the massive stars. As well known, the massive star is
deeply embedded in compact clouds and far from us. Thus the
characteristics of MSFs are difficult to be determined\rf{4}. So
the search for molecular outflows in MSF regions and study of them
are significant to understand the process of the MSF.

 The phenomenon that massive stars are always close to each
other making it hard for us to obtain the direct information from
the star formations. As a result, the solitary MSF region provides
a dramatic opportunity to throw  some light on the myth of the
MSF.

 Whether the exciting source of UC HII is the driving source
of outflow or not is significant to the upper mass of the star. So
the region with only one IRAS source and HII is critical to this
study. Because in such region we can easily determine which is
exciting source of UC HII and which is the driving source of
outflow.

 In this paper, we report a new discovered outflow in a
lonely massive star formation with an UC HII. We present the CO
map of this region around 02$^{\rm h}$ 46$^{\rm m}$
11.7$^{\rm s}$+61$^{\circ}$ 47$^{'}$ 34.02$^{''}$ (1950). In II we
summarize the observation, and in III the result of the
observation is shown,
 and in IV we present our discussions, and in the last part we draw
a conclusion.

\para{\large\bf{2}~~Observation}

\vspace{3.5mm}
Observations of the  J=3-2 transition of CO were made
 with KOSMA 3-m telescope of Gornergrat Observatory in the
 Swiss Alps in October 2002. The half-power beam width of the telescope
 was
 $80^{''}$ at 345\,GHz, the frequency of CO J=3-2. The pointing
 accuracy was better than $10^{''}$.The system temperature was about 260\,K.
 The SIS receivers were operated in double sideband mode. The Variable
 Resolution  Acousto Optic Spectrometer was used with a bandwith of 400
 MHz.
 The  velocity resolution is  0.294\,km/s. The
 main beam efficiency of the telescope is 66\% at 345\,GHz and the forward
 efficiency is 93\%.
 The mapped area was 13$^{'}$$\times$13$^{'}$with 0.5$^{'}$ grid
 spacing,and the integration time was 54 sec for each
 position. The mapping procedure was done in the On-The-Fly modus.

  \para{\large\bf{3}~~Results}

  \bc{\small\bf

 Table 1~~   The parameters of the outflow
}\\[2mm]

\fns \tabcolsep 1mm
\begin{tabular}{cccccccccc}
\hline\\[-3.6mm]\hline
 D & M  & P & E & $\bar{\nu}$ & t & F & L$_{\rm co}$ & $\dot{M}$ & M$_{\rm cloud}$\\
   pc& M$_{\odot}$ & M$_{\odot}\cdot$\,km$\cdot$s$^{-1}$ & ergs & km$\cdot$s$^{-1}$ & yr&
  M$_{\odot}$$\cdot$km$\cdot$s$^{-1}$$\cdot$yr$^{-1}$ &
  L$_{\odot}$ & $M_{\odot}$$\cdot$$a^{-1}$ &  M$_{\odot}$\\
\hline
 4213  & 85 & 271& $3\times10^{46}$& 3.2 & $0.35\times10^6$ & $0.80\times10^{-3}$
 & 0.71 & $0.26\times10^{-5}$ & 3000  \\
 \hline\\[-3.6mm]\hline%\\[-4.5mm]\hline
 \end{tabular}
 \ec

 %\vspace*{-4mm}
  \para{\large\bf{4}~~Discussion}

\vspace{3.5mm}
 \no a)The  mass of the central star

The Simbad data show there is an
 UC HII region in this cloud, which demonstrates this is
 a MSF region. The two colour index are
            log($\frac{F25}{F12}$)=0.914$>$0.57 and
            log($\frac{F60}{F12}$)=1.45$>$1.3
 , where F$_{x}$ is the $IRAS$ flux. The luminosity
 is about 1.6$\times10^{6}$L$_{\odot}$.

  The total luminosity of
 the star in process of accretion is
 composed of two parts, the accretion luminosity converted by the
 gravitational energy of the accreted matter and the
 luminosity by nuclear reaction in the star. Because of the existence of
 HII, the accretion rate can not be large, so we assume that the total luminosity is
 from nuclear reaction. Using the mass-luminosity relation of main
 sequence star, $\frac{L_{\rm star}}{L_{\odot}}=(\frac{M_{\rm star}}{M_{\odot}})^{4}$,
 we can get the mass of star about 12\,M$_{\odot}$,
 assuming the IRAS source consisted of only one star.


\no b)The driving source of the outflow

 The simbad data show there is only an IRAS source in
  this region. So the driving source of this flow is
  IRAS02461+6147. In addition, the position of IRAS02461+6147
  overlaps with the geometric position of the driving source of
  the outflow, which illustrates it is the driving source.

     The IRAS02461+6147 is also the exciting source of the UC
    HII region. The mass of the central star
    indicates that this source is likely a single source. If this
    is true, it indicates the massive star in the phase of the UC
    HII can also continue to accrete and increase its mass.

\para{\large\bf{5}~~Conclusion}

\vspace{3.5mm}
 We mapped lines of CO J=3-2 and a bipolar outflow is
found. The physical parameters are obtained, and the results are
listed at table 1. We estimate the mass of the IRAS source, which
shows it is a massive star. The driving source of outflow is IRAS
02461+6147, which illustrates that the exciting source of UC HII
can also be the driving source of outflow, thus accretes and
increases its mass.

\vs\vn{\bf ACKNOWLEDGEMENTS}~~The poject is supported by 10128306
NSFC, 10133020 NSFC and G1999075405 NKBRSF. We thank the
assistance of Garnergrat Observatory, Koln University and Qinghai
Station. We also thank J. Wang for discussion.

\bc
{\bf References}
\ec

\vspace{-4mm}
\no \fns

 \no Zhang Q, Hunter T R. ApJ, 2001, 552: L167\\
\no Snell R L, Lorne R B, Plambeck R L, ApJ, 1980, 239L: 17s\\
\no Shang Hsien Shu Frank H, Glass gold, Alfred E. ApJ, 1998, 493L: 91s\\
\no Shepherd D S, Watson A M, Sargent A I, et al. ApJ, 1998, 507: 861s\\

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