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)
<Astrophys. J., 884, 4 (2019)>
=2019ApJ...884....4K 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 NH3 (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 NH3
(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 70µm 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
NH3, HC5N, HC7N, HNCO, H2O, CH3OH, 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.
C18O (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:
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FileName Lrecl Records Explanations
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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
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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 850µm (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 : H2O Southern Gal. Plane Survey, HOPS. II (Purcell+, 2012)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (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
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Bytes Format Units Label Explanations
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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)
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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 2006ApJ...645..337H).
c = Schlafly et al. (2014, J/ApJ/786/29).
d = Lombardi et al. (2011A&A...535A..16L 2011A&A...535A..16L).
e = Baxter et al. (2009, J/AJ/138/963).
f = Bonatto et al. (2006A&A...445..567B 2006A&A...445..567B).
g = Xu et al. (2011ApJ...733...25X 2011ApJ...733...25X).
h = Rygl et al. (2010, J/A+A/515/A42).
i = Rygl et al. (2012A&A...539A..79R 2012A&A...539A..79R).
j = Moscadelli et al. (2009ApJ...693..406M 2009ApJ...693..406M).
Note (3): The total mass and total area are calculated as the sum of all H2
column density and area, respectively, mapped in each cloud by Herschel.
Note (4): The completeness represents the percentage of pixels with AV>10
in the Herschel H2 column density maps that were observed by KEYSTONE.
We assumed an extinction conversion factor of NH2/AV=0.94x1021
(Bohlin+ 1978ApJ...224..132B 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.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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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] NH3 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] NH3 (1,1) centroid LSR velocity
106-109 F4.1 [cm-2] logNH3 [13.1/15.5] log para-NH3 column density
111-114 F4.1 [cm-2] logH2 [21/22.8]? Median log H2 column density (5)
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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/π)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.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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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 (αvir)
defined as Mvir/Mobs
26- 31 F6.1 Msun MVir [3/1940] Virial mass (Mvir) (6)
33- 36 F4.2 km/s signt [0.07/1.8] Non-thermal component of
velocity dispersion (σnt)
38- 41 F4.1 [10-7J] logOmeG [42.1/48]? log of gravitational energy
density (log|ΩG|) in erg units (7)
43- 46 F4.1 [10-7J] logOmeK [42.5/47.4]? log of kinetic energy density
(logΩK) in erg units (7)
48- 51 F4.1 [10-7J] logOmePw [42.6/47.3]? log of cloud weight
pressure energy density (log|ΩPw|)
in erg units (7)
53- 56 F4.1 [10-7J] logOmePt [44.3/48.2]? log of turbulent
pressure energy density (log|ΩPt|)
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)
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Note (6): Calculated using Equation 1: Mvir=(Rσ2R)/aG where
σ 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 ρ(r)∝r-k (Bertoldi & McKee 1992ApJ...395..140B 1992ApJ...395..140B).
See Section 3.5.
Note (7): ΩPw=-4πPwR3 (Equation (4))
ΩG=(-1/(2.π0.5)).((GM2)/R) (Equation (5))
ΩK=3/2.Mσ2 (Equation (6))
where M is the observed structure mass, R is the effective radius,
G is the gravitational constant, σ2 is the same as
in Equation (3):
σ2=σ2ν-((kBT)/mNH3)+((kBT)/µpmH),
and Pw is cloud weight pressure: Pw=πG\barNN(µHmH)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): ΩPt is calculated from Equation (4),
with Pw being replaced with Pt given by
PT=µHmHxρC18Oxσ2C18O (Equation (8)) where
σC18O is the velocity dispersion measured from C18O (3-2), a
moderate density tracer, and ρC18O is the volume density at
which the C18O (3-2) emission originates. See Section 4.5.
Note (9): That were saturated in the H2 column density map.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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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 (αvir<2)
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Note (5): Median kinetic gas temperature and velocity dispersion for all
reliably fit ammonia pixels.
Note (6): where NH3 (1,1) integrated intensity is greater than 1K.km/s.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Mar-2021