J/ApJ/828/59 Molecular clouds in the Milky Way with CO obs. (Su+, 2016) ================================================================================ The distant outer gas arm between l=35 and l=45. Su Y., Sun Y., Li C., Zhang S., Zhou X., Fang M., Yang J., Chen X. =2016ApJ...828...59S (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Molecular clouds ; Milky Way ; Radio lines ; Surveys Keywords: Galaxy: structure; ISM: molecules; radio lines: ISM Abstract: The Galactic plane has been mapped from l=34.75{deg} to 45.25{deg} and b=-5.25{deg} to 5.25{deg} in the CO (J=1-0) emission with the 13.7m telescope of the Purple Mountain Observatory. The unbiased survey covers a large area of 110 square degrees sampled every 30" with a velocity resolution of ~0.2km/s. In this paper, we present the result of an unbiased CO survey of this longitude and latitude range in the velocity range from -60 to -10km/s. Over 500 molecular clouds (MCs) are picked out from the ^12^CO (J=1-0) emission, and 131 of these MCs are associated with ^13^CO emission. The distant MCs, which lie beyond the solar circle and are mostly concentrated in the Galactic plane, trace the large-scale molecular gas structure over 10 degrees of Galactic azimuth. We find that the distribution of the distant MCs can be well fitted by a Gaussian function with a full width at half maximum (FWHM) of 0.7{deg} with the Galactic latitude. We suggest that the CO emission of the segment is from the Outer Arm. The physical mid-plane traced by the Outer Arm seems to be slightly displaced from the IAU-defined plane on a large scale, which could be explained by the warped plane at large Galactocentric distances of >~10kpc and the apparent tilted mid-plane to the projected IAU-defined plane caused by the Sun's z-height above the disk for distances near and within the Solar circle. After removing the effect of the warp and tilted structure, the scale height of the MCs in the Outer Arm is about 0.6{deg} or 160pc at a heliocentric distance of 15kpc. If the inner plane of our Galaxy is flat, we can derive an upper limit of the Sun's offset of ~17.1pc above the physical mid-plane of the Milky Way. We also discuss the correlations between the physical parameters of the distant MCs, which is quite consistent with the result of other studies of this parameter. Description: The Milky Way Imaging Scroll Painting (MWISP) project is a high resolution (50") ^12^CO (J=1-0), ^13^CO (J=1-0), and C^18^O (J=1-0) survey of the northern Galactic plane, performed with the Purple Mountain Observatory Delingha 13.7m telescope. The survey started in 2011, and will cover Galactic longitudes from l=-10{deg} to 250{deg} and latitudes from b=-5{deg} to 5{deg} over a period of ~10 years. We mapped ~110 square degrees (439 cells) in the region between Galactic longitudes 34.75-45.25{deg} and latitudes -5.25{deg} to 5.25{deg} during 2011 November to 2015 March using the 13.7m millimeter-wavelength telescope located at Delingha in China. The molecular lines of ^12^CO (J=1-0), ^13^CO (J=1-0), and C^18^O (J=1-0) were observed simultaneously with the On-The-Fly (OTF) method. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 53 575 Parameters of 575 molecular clouds identified from ^12^CO(J=1-0) emission table2.dat 53 131 Parameters of 131 molecular clouds identified from ^13^CO(J=1-0) emission table3.dat 91 28 Molecular clouds associated with massive star formation regions -------------------------------------------------------------------------------- See also: VIII/40 : GB6 catalog of radio sources (Gregory+ 1996) VIII/58 : A Survey of Radio H II Regions in the Northern Sky (Lockman+ 1989) VIII/39 : Composite CO Survey of the Milky Way (Dame+ 1987) J/ApJS/224/7 : CO obs. of the outer arm in the 2nd quadrant (Du+, 2016) J/ApJS/221/26 : Radio obs. of Galactic WISE HII regions (Anderson+, 2015) J/ApJ/798/L27 : CO obs. of molecular clouds in the 2nd quadrant (Sun+, 2015) J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014) J/AJ/147/46 : Properties of clumps in the NAN complex (Zhang+, 2014) J/ApJ/738/27 : Galactic HII regions RRL and continuum data (Balser+, 2011) J/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011) J/ApJ/723/492 : Properties of GRS molecular clouds (Roman-Duval+, 2010) J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009) J/A+A/382/513 : Galaxy warps in the HDF North and South (Reshetnikov+, 2002) J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001) J/A+AS/115/81 : A CS(2-1) survey of UC HII regions (Bronfman+, 1996) J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993) J/ApJS/63/821 : Inner Galaxy Molecular clouds & cloud cores (Scoville+, 1987) http://www.radioast.nsdc.cn/mwisp.php : MWISP home page Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I03 --- Seq Running index number 5- 10 F6.3 deg GLON Galactic longitude 12- 17 F6.3 deg GLAT Galactic latitude 19- 24 F6.2 km/s VLSR [-57/-10] Local Standard of Rest velocity 26- 29 F4.2 km/s VFWHM [0.3/7] Full Width at Half Maximum of VLSR 31- 34 F4.2 K Tpeak [1.8/10] Peak temperature 36- 40 F5.2 arcmin2 Area [0.6/45.3] Area 42- 46 F5.2 K.km/s W12CO [0.5/14.4] Integrated ^12^CO emission line flux 48- 53 F6.2 K.km/s.arcmin2 L12CO [1/223] The ^12^CO luminosity -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I03 --- Seq Running index number 5- 10 F6.3 deg GLON Galactic longitude 12- 17 F6.3 deg GLAT Galactic latitude 19- 24 F6.2 km/s VLSR [-53/-10] Local Standard of Rest velocity 26- 29 F4.2 km/s VFWHM [0.4/5.1] Full Width at Half Maximum of VLSR 31- 34 F4.2 K Tpeak [0.8/3] Peak temperature 36- 40 F5.2 arcmin2 Area [0.6/7.2] Area 42- 46 F5.2 K.km/s W13CO [0.3/5] Integrated ^13^CO emission line flux 48- 53 F6.2 K.km/s.arcmin2 L13CO [0.4/35] The ^13^CO luminosity -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- --- [MWISP] 7- 21 A15 --- MWISP Molecular cloud (MC) name (GLLL.lll+BB.bbb) from the ^13^CO (J=1-0) emission (table 2) 23 A1 --- f_MWISP e: from the ^12^CO (J=1-0) emission (table 1) 25- 30 F6.3 deg GLON MC Galactic longitude 32- 37 F6.3 deg GLAT MC Galactic latitude 39- 44 F6.2 km/s Vel [-51/-12] MC LSR velocity (from table 2 or 1) 46- 65 A20 --- Tracer Tracer designation (1) 67- 72 F6.3 deg GTLAT ? Tracer Galactic longitude (1) 74- 79 F6.3 deg GTLON ? Tracer Galactic latitude (1) 81- 86 F6.2 km/s VLSR [-55.1/-10.5]? LSR velocity (1) 87 A1 --- f_VLSR [f] Flag on VLSR (2) 89- 91 A3 --- Ref Reference(s) (3) -------------------------------------------------------------------------------- Note (1): We use HII regions and 6.7GHz methanol masers to trace massive star formation regions. The position and the velocity of the HII region is from the radio continuum emission and the radio recombination line, respectively. The position and the velocity of the 6.7 GHz maser is from the observations of the maser survey (Green & McClure-Griffiths 2011MNRAS.417.2500G; Breen+ 2015MNRAS.450.4109B). Based on Tables 1 and 2, we do not find the CO counterpart of the 6.7GHZ maser G38.565+0.538 with the LSR velocity of -28.8km/s (Table 1 in Breen+ 2015MNRAS.450.4109B). However, a point-like MC with a temperature of ~1.5K and the LSR velocity of -35.40km/s is detected from the ^12^CO (J=1-0) data at the maser's position. Note (2): f = The velocity of the HII region is from the CS (J=2-1) observation. Note (3): Reference as follows: 1 = Lockman (1989, VIII/58), 2 = Bronfman et al. (1996, J/A+AS/115/81), 3 = Gregory et al. (1996, VIII/40), 4 = Anderson et al. (2011, J/ApJS/194/32), 5 = Balser et al. (2011, J/ApJ/738/27), 6 = Green & McClure-Griffiths (2011MNRAS.417.2500G), 7 = Bania et al. (2012ApJ...759...96B), 8 = Anderson et al. (2015, J/ApJS/221/26), 9 = Breen et al. (2015MNRAS.450.4109B). -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Dec-2016