J/ApJ/884/4 KEYSTONE: ammonia structures in Galactic GMCs (Keown+, 2019) ================================================================================ KFPA Examinations of Young STellar Object Natal Environments (KEYSTONE): hierarchical ammonia structures in Galactic giant molecular clouds. Keown J., Di Francesco J., Rosolowsky E., Singh A., Figura C., Kirk H., Anderson L.D., Chen M.C.-Y., Elia D., Friesen R., Ginsburg A., Marston A., Pezzuto S., Schisano E., Bontemps S., Caselli P., Liu H.-L., Longmore S., Motte F., Myers P.C., Offner S.S.R., Sanhueza P., Schneider N., Stephens I., Urquhart J. (The KEYSTONE Collaboration) =2019ApJ...884....4K ================================================================================ ADC_Keywords: Interstellar medium; Molecular clouds; Velocity dispersion; Surveys; Radio lines; Infrared sources Keywords: ISM: kinematics and dynamics ; ISM: structure ; stars: formation Abstract: We present initial results from the K-band Focal Plane Array Examinations of Young STellar Object Natal Environments survey (KEYSTONE), a large project on the 100m Green Bank Telescope mapping ammonia emission across 11 giant molecular clouds at distances of 0.9-3.0kpc (Cygnus X North, Cygnus X South, M16, M17, Mon R1, Mon R2, NGC 2264, NGC 7538, Rosette, W3, and W48). This data release includes the NH_3_ (1,1) and (2,2) maps for each cloud, which are modeled to produce maps of kinetic temperature, centroid velocity, velocity dispersion, and ammonia column density. Median cloud kinetic temperatures range from 11.4+/-2.2K in the coldest cloud (Mon R1) to 23.0+/-6.5K in the warmest cloud (M17). Using dendrograms on the NH_3_ (1,1) integrated intensity maps, we identify 856 dense gas clumps across the 11 clouds. Depending on the cloud observed, 40%-100% of the clumps are aligned spatially with filaments identified in H2 column density maps derived from spectral energy distribution fitting of dust continuum emission. A virial analysis reveals that 523 of the 835 clumps (~63%) with mass estimates are bound by gravity alone. We find no significant difference between the virial parameter distributions for clumps aligned with the dust-continuum filaments and those unaligned with filaments. In some clouds, however, hubs or ridges of dense gas with unusually high mass and low virial parameters are located within a single filament or at the intersection of multiple filaments. These hubs and ridges tend to host water maser emission, multiple 70{mu}m detected protostars, and have masses and radii above an empirical threshold for forming massive stars. Description: Data were obtained as part of the K-band Focal Plane Array (KFPA) Examinations of Young STellar Object Natal Environments (KEYSTONE) survey, a large project on the Green Bank Telescope (GBT) that mapped NH_3_, HC_5_N, HC_7_N, HNCO, H_2_O, CH_3_OH, and CCS emission across 11 giant molecular clouds (Cygnus X North, Cygnus X South, M16, M17, Mon R1, Mon R2, NGC 2264, NGC 7538, Rosette, W3, and W48) at distances between 0.9 and 3kpc. Observations were conducted between 2016 October and 2019 March for a total of 356.25 observing hours, including overheads. Observations were made with the GBT's KFPA, which has seven beams arranged in the shape of a hexagon with beam centers separated by ~95" on the sky. See Section 2.2. Herschel Level 2.5 data products at 70, 160, 250, 350, and 500um for each KEYSTONE region were downloaded from the European Space Agency Herschel Science Archive. See Section 2.3. C^18^O (3-2) data cubes observed by the HARP-ACSIS spectrometer on the James Clerk Maxwell Telescope (JCMT) were obtained from the JCMT Science Archive. See Section 2.4. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 73 11 KEYSTONE target giant molecular clouds (GMCs) table4.dat 114 856 Leaves catalog 1 table5.dat 76 856 Leaves catalog 2 table6.dat 66 12 Cloud statistics -------------------------------------------------------------------------------- See also: B/jcmt : Jame Clerk Maxwell Telescope Science Archive (CADC, 2003) VI/139 : Herschel Observation Log (Herschel Science Centre, 2013) J/AJ/114/198 : The Monoceros R2 Cluster (Carpenter+ 1997) J/A+A/437/467 : VLT-FLAMES survey of massive stars (Evans+, 2005) J/AJ/129/393 : UBV photometry in W3 (Oey+, 2005) J/ApJ/625/891 : Clumps in NGC 7538 at 450 and 850{mu}m (Reid+, 2005) J/A+A/432/369 : Leiden Atomic and Molecular Database (LAMDA) (Schoeier+, 2005) J/ApJ/646/1009 : Structures of dust in Perseus molecular cloud (Kirk+, 2006) J/A+A/476/1243 : Millimeter continuum mapping of Cygnus X (Motte+, 2007) J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008) J/ApJ/675/464 : Chandra observations of NGC 2244 (Wang+, 2008) J/AJ/138/963 : Rotation of NGC 2264 members (Baxter+, 2009) J/ApJ/696/1278 : The extended star-forming environment of M17 (Povich+, 2009) J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010) J/A+A/515/A42 : Catalog of high extinction clouds (Rygl+, 2010) J/A+A/527/A135 : Massive Dense Cores in Cygnus-X (Csengeri+, 2011) J/ApJ/741/110 : The BGPS. VII. Massive star-forming regions (Dunham+, 2011) J/A+A/530/A118 : G29.96-0.02 and G35.20-1.74 1mm and 3mm maps (Pillai+, 2011) J/ApJ/743/39 : Spitzer obs. of W3 molecular cloud (Rivera-Ingraham+, 2011) J/MNRAS/418/1689 : Red MSX water maser and ammonia emissions (Urquhart+, 2011) J/A+A/543/A101 : OB stars in Cygnus OB2 association (Comeron+, 2012) J/MNRAS/426/1972 : H_2_O Southern Gal. Plane Survey, HOPS. II (Purcell+, 2012) J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH_3_ (Wienen+, 2012) J/ApJS/208/14 : BGPS. IX. Data release 2. (Ginsburg+, 2013) J/A+A/570/A1 : Cygnus-X CO and SiO outflows datacubes (Duarte-Cabral+, 2014) J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014) J/MNRAS/443/3218 : NGC 7538 IRS 1-3 and IRS 9 sources (Mallick+, 2014) J/ApJ/794/124 : Young star forming reg NGC2264 Spitzer sources (Rapson+, 2014) J/ApJ/786/29 : Catalog of distances to molecular clouds (Schlafly+, 2014) J/A+A/584/A91 : Cat. of dense cores in Aquila from Herschel (Konyves+, 2015) J/A+A/575/A9 : M17-SW datacubes in C and CO lines (Perez-Beaupuits+, 2015) J/AJ/150/191 : IR photometry of YSOs in Cygnus-X DR15 (Rivera-Galvez+, 2015) J/MNRAS/452/4029 : RMS survey (Urquhart+, 2015) J/A+A/591/A5 : ATLASGAL dense filamentary structures (Li+, 2016) J/MNRAS/459/342 : Dense cores in Taurus L1495 cloud (Marsh+, 2016) J/ApJ/824/29 : ATLASGAL clumps with IRAS flux & MALT90 data (Stephens+, 2016) J/ApJ/822/59 : BGPS. XIV. Molecular cloud clumps GBT obs. (Svoboda+, 2016) J/ApJ/846/144 : Virial analysis of the dense cores in Orion A (Kirk+, 2017) J/A+A/607/A22 : Monoceros R2 filament hub FIR observations (Rayner+, 2017) J/A+A/602/A77 : HOBYS: 46 MDCs found in NGC 6334 (Tige+, 2017) J/A+A/615/A125 : Molecular cloud in Corona Australis (Bresnahan+, 2018) J/ApJS/237/27 : Radio Ammonia Mid-plane pilot survey (RAMPS) (Hogge+, 2018) J/A+A/625/A134 : NGC 6357 massive dense cores (Russeil+, 2019) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 A14 --- Region Region identifier 16- 17 I2 h RAh Hour of right ascension (J2000) (1) 19- 20 I2 min RAm Minute of right ascension (J2000) 22- 27 F6.3 s RAs Second of right ascension (J2000) 29 A1 --- DE- Sign of declination (J2000) (1) 30- 31 I2 deg DEd Degree of declination (J2000) (1) 33- 34 I2 arcmin DEm Arcminute of declination (J2000) 36- 41 F6.3 arcsec DEs Arcsecond of declination (J2000) 43- 45 F3.1 kpc Dist [0.9/3] Distance 47- 49 F3.1 kpc e_Dist [0.1/0.5]? Dist uncertainty 51- 53 A3 --- r_Dist Reference(s) for Dist (2) 55- 59 E5.2 Msun MassH2 [4900/1.4e+06] Total mass (3) 61- 65 E5.2 pc2 AreaH2 [140/8800] Total area (3) 67- 68 I2 --- Ntile [5/43] Number of footprint observed; each footprint is 10'x10' 69 A1 --- n_Ntile [+] +: a partially completed tile was also observed in that region 71- 73 I3 --- Comp [31/100] Completeness (4) -------------------------------------------------------------------------------- Note (1): The RA and DEC listed are the mid-point of the entire mapped area. Note (2): Reference as follows: b = Hachisuka et al. (2006ApJ...645..337H). c = Schlafly et al. (2014, J/ApJ/786/29). d = Lombardi et al. (2011A&A...535A..16L). e = Baxter et al. (2009, J/AJ/138/963). f = Bonatto et al. (2006A&A...445..567B). g = Xu et al. (2011ApJ...733...25X). h = Rygl et al. (2010, J/A+A/515/A42). i = Rygl et al. (2012A&A...539A..79R). j = Moscadelli et al. (2009ApJ...693..406M). Note (3): The total mass and total area are calculated as the sum of all H_2_ column density and area, respectively, mapped in each cloud by Herschel. Note (4): The completeness represents the percentage of pixels with A_V_>10 in the Herschel H_2_ column density maps that were observed by KEYSTONE. We assumed an extinction conversion factor of NH_2_/A_V_=0.94x10^21^ (Bohlin+ 1978ApJ...224..132B). The completion percentages for M16, M17, and W48 account for the Radio Ammonia Mid-Plane Survey (RAMPS; Hogge+, 2018, J/ApJS/237/27) intended coverage of those regions. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 A14 --- Region Region identifier 16- 18 I3 --- Leaf [0/199] Leaf identifier 20- 27 F8.4 deg RAdeg [34.5/349.4] Mean Right Ascension (J2000) 29- 36 F8.4 deg DEdeg [-16.7/62.3] Mean Declination (J2000) 38- 40 I3 deg PA [45/225] Position angle of major axis (1) 42- 45 F4.1 arcsec MajAxis [8.1/61.1] Major axis (2) 47- 50 F4.1 arcsec MinAxis [3.8/37.4] Minor axis (2) 52- 55 F4.2 pc Reff [0.07/1] Effective radius (3) 57- 60 F4.2 pc E_Reff [0/0.98] Upper uncertainty in Reff 62- 65 F4.2 pc e_Reff [0/0.64] Lower uncertainty in Reff 67- 72 F6.1 Msun Mobs [1.3/4451.6]? Observed leaf mass (4) 74- 79 F6.1 Msun Mclip [0.1/2672]? Leaf lower mass limit from "clipping" technique 81- 84 F4.1 K TK [9.1/36] Average kinetic gas temperature 86- 88 F3.1 K e_TK [0.2/5] Uncertainty in TK 90- 93 F4.2 km/s sigma [0.1/1.72] NH_3_ velocity dispersion 95- 98 F4.2 km/s e_sigma [0/0.3] Uncertainty in sigma 100-104 F5.1 km/s VLSR [-59.2/47.8] NH_3_ (1,1) centroid LSR velocity 106-109 F4.1 [cm-2] logNH3 [13.1/15.5] log para-NH_3_ column density 111-114 F4.1 [cm-2] logH2 [21/22.8]? Median log H_2_ column density (5) -------------------------------------------------------------------------------- Note (1): Counterclockwise from the west on sky. Note (2): Measured by astrodendro based on the intensity weighted second moment in the direction of greatest elongation. Although the intensity-weighted major and minor axes of some sources are less than the 32" beam size of the observations, our culling criteria ensure that their total areas when considering all their associated pixels are larger than 32". Note (3): Defined as Reff=(A/{pi})^1/2^, where A is the area of all pixels in the leaf's mask on the position-position plane. Note (4): From the sum of its H2 column density. Note (5): For leaf measured from the spatially-filtered column density map and used as N in Equation 7. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 A14 --- Region Region identifier 16- 18 I3 --- Leaf [0/199] Leaf identifier 20- 24 F5.2 --- aVir [0.16/69.3]? Virial parameter ({alpha}_vir_) defined as M_vir_/M_obs_ 26- 31 F6.1 Msun MVir [3/1940] Virial mass (M_vir_) (6) 33- 36 F4.2 km/s signt [0.07/1.8] Non-thermal component of velocity dispersion ({sigma}_nt_) 38- 41 F4.1 [10-7J] logOmeG [42.1/48]? log of gravitational energy density (log|{Omega}_G_|) in erg units (7) 43- 46 F4.1 [10-7J] logOmeK [42.5/47.4]? log of kinetic energy density (log{Omega}_K_) in erg units (7) 48- 51 F4.1 [10-7J] logOmePw [42.6/47.3]? log of cloud weight pressure energy density (log|{Omega}_Pw_|) in erg units (7) 53- 56 F4.1 [10-7J] logOmePt [44.3/48.2]? log of turbulent pressure energy density (log|{Omega}_Pt_|) in erg units (8) 58- 62 A5 --- OnFil Leaf is on-filament 64- 68 A5 --- Hub Leaf is a hub 70- 70 I1 --- Nps [0/9] Number of 70um point sources within boundary 73- 76 F4.2 --- Bad [0/0.6] Fraction of leaf pixels (9) -------------------------------------------------------------------------------- Note (6): Calculated using Equation 1: M_vir_=(R{sigma}^2^R)/aG where {sigma} is the velocity dispersion of the core (including both the thermal and nonthermal components), R is the core radius, G is the gravitational constant, and a=(1-k/3)/(1-2k/5) (Equation (2)) is a term which accounts for the radial power-law density profile of a core, where {rho}(r){propto}r^-k^ (Bertoldi & McKee 1992ApJ...395..140B). See Section 3.5. Note (7): {Omega}_Pw_=-4{pi}P_w_R^3^ (Equation (4)) {Omega}_G_=(-1/(2.{pi}^0.5^)).((GM^2^)/R) (Equation (5)) {Omega}_K_=3/2.M{sigma}^2^ (Equation (6)) where M is the observed structure mass, R is the effective radius, G is the gravitational constant, {sigma}^2^ is the same as in Equation (3): {sigma}^2^={sigma}^2^_{nu}_-((k_B_T)/m_NH3_)+((k_B_T)/{mu}_p_m_H_), and Pw is cloud weight pressure: P_w_={pi}G{\barN}N({mu}_H_m_H_)^2^ (Equation (7)) where {\bar{N}} is the mean cloud column density and N is the column density at the structure. See Section 4.4. Note (8): {Omega}_Pt_ is calculated from Equation (4), with P_w_ being replaced with Pt given by P_T_={mu}_H_m_H_x{rho}_C18O_x{sigma}^2^_C18O_ (Equation (8)) where {sigma}_C18O_ is the velocity dispersion measured from C^18^O (3-2), a moderate density tracer, and {rho}_C18O_ is the volume density at which the C^18^O (3-2) emission originates. See Section 4.5. Note (9): That were saturated in the H2 column density map. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 A14 --- Region Region identifier 16- 19 F4.1 K Tmed [11.4/23] Median kinetic gas temperature (5) 21- 23 F3.1 K e_Tmed [2.2/6.5] Tmed uncertainty 25- 27 F3.1 km/s Sigmed [0.2/0.7] Median velocity dispersion (5) 29- 31 F3.1 km/s e_Sigmed [0.1/0.3] Sigmed uncertainty 33- 35 I3 --- Nps [9/130] Number of protostars identified (6) 37- 41 F5.1 pc2 Area [1.9/137.6] Area of map (6) 43- 47 I5 Msun Mass [303/55013] Total mass (6) 49- 51 I3 --- Totl [12/194] Total number of ammonia leaves with mass estimates identified in cloud 53- 56 F4.2 --- fFil [0.35/1] Fraction of total leaves that are on-filament 58- 61 F4.2 --- fProto [0.17/0.58] Fraction of total leaves that are protostellar 63- 66 F4.2 --- fBound [0.34/0.89] Fraction of total leaves that are bound ({alpha}_vir_<2) -------------------------------------------------------------------------------- Note (5): Median kinetic gas temperature and velocity dispersion for all reliably fit ammonia pixels. Note (6): where NH_3_ (1,1) integrated intensity is greater than 1K.km/s. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Mar-2021