J/ApJ/846/144 Virial analysis of the dense cores in Orion A (Kirk+, 2017)
The Green Bank Ammonia Survey: dense cores under pressure in Orion A.
Kirk H., Friesen R.K., Pineda J.E., Rosolowsky E., Offner S.S.R.,
Matzner C.D., Myers P.C., Di Francesco J., Caselli P., Alves F.O.,
Chacon-Tanarro A., Chen H.-H., Chen M.C.-Y., Keown J., Punanova A.,
Seo Y.M., Shirley Y., Ginsburg A., Hall C., Singh A., Arce H.G.,
Goodman A.A., Martin P., Redaelli E.
<Astrophys. J., 846, 144 (2017)>
=2017ApJ...846..144K 2017ApJ...846..144K
ADC_Keywords: Molecular clouds; Millimetric/submm sources; Velocity dispersion;
YSOs; Interstellar medium
Keywords: ISM: kinematics and dynamics ; radio lines: ISM ; stars: formation ;
submillimeter: ISM
Abstract:
We use data on gas temperature and velocity dispersion from the Green
Bank Ammonia Survey and core masses and sizes from the James Clerk
Maxwell Telescope Gould Belt Survey to estimate the virial states of
dense cores within the Orion A molecular cloud. Surprisingly, we find
that almost none of the dense cores are sufficiently massive to be
bound when considering only the balance between self-gravity and the
thermal and non-thermal motions present in the dense gas. Including
the additional pressure binding imposed by the weight of the ambient
molecular cloud material and additional smaller pressure terms,
however, suggests that most of the dense cores are pressure-confined.
Description:
NH3 observations were obtained through the Green Bank Ammonia Survey
(GAS), a large project to map the ammonia (1,1), (2,2), and (3,3)
rotation-inversion transitions across the high-extinction regions of
nearby Gould Belt molecular clouds using the Green Bank Telescope's
K-band Focal Plane Array. The survey strategy, data reduction
procedure, and basic data properties are described in detail in
Friesen+ (2017ApJ...843...63F 2017ApJ...843...63F). The spatial resolution is 32"
(0.064pc), while the spectral resolution is 0.07km/s.
For our analysis, we use the dense core catalog presented in Lane+
(2016ApJ...833...44L 2016ApJ...833...44L), which covers the entire Orion A complex with
the JCMT SCUBA-2 850um. See section 2.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 237 Dense core properties
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See also:
B/jcmt : Jame Clerk Maxwell Telescope Science Archive (CADC, 2003)
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
J/ApJS/125/161 : A database of dense cores mapped in ammonia (Jijina+, 1999)
J/ApJ/559/307 : Sub-mm mapping in Orion B molecular cloud (Johnstone+, 2001)
J/ApJ/646/1009 : Structures of dust in Perseus molecular cloud (Kirk+, 2006)
J/A+A/462/L17 : Dense cores in interstellar molecular clouds (Alves+, 2007)
J/ApJ/665/1194 : Dense cores in the Orion A cloud survey (Ikeda+, 2007)
J/ApJ/668/1042 : Dense cores in Perseus molecular cloud (Kirk+, 2007)
J/ApJ/655/351 : Massive quiescent cores in Orion. II. (Li+, 2007)
J/MNRAS/374/1413 : SCUBA survey of Orion (Nutter+, 2007)
J/ApJ/664/928 : Starless cores in HCN(J=1-0) (Sohn+ 2007)
J/ApJ/680/495 : Interstellar clouds in the Gould belt (Harvey+, 2008)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJ/696/298 : Dense cores in Perseus (Foster+, 2009)
J/A+A/498/167 : Embedded sources in L 1688 (van Kempen+, 2009)
J/ApJ/710/1247 : Dense cores in Gould Belt clouds (Sadavoy+, 2010)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSOs (Megeath+, 2012)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/A+A/566/A45 : Orion optical-depth & column-density maps (Lombardi+, 2014)
J/A+A/564/A68 : Orion A GMC 13CO and C18O maps (Shimajiri+, 2014)
J/MNRAS/449/1769 : Orion A North prestellar core properties (Salji+, 2015)
J/A+A/574/A104 : Dense cores in L1495/B213 complex (Tafalla+, 2015)
J/ApJ/831/67 : Galactic CHaMP. III. 12CO dense clumps (Barnes+, 2016)
J/ApJ/817/167 : JCMT Gould Belt Survey: dense cores in Orion B (Kirk+, 2016)
J/MNRAS/461/4022 : JCMT Gould Belt Survey: Southern Orion A (Mairs+, 2016)
J/A+A/587/A153 : VISION I. VISTA Orion A Survey (Meingast+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [5/907] Sequential Core ID (1)
5- 12 F8.5 deg RAdeg [83.64/84.17] Right Ascension,
core's central position (J2000)
14- 21 F8.5 deg DEdeg [-6.3/-4.8] Declination,
core's central position (J2000)
23- 27 F5.2 Msun Mass [0.09/11.1] Core mass (2)
29- 33 F5.3 pc Reff [0.01/0.2] Effective radius (3)
35- 38 F4.2 --- Conc [0.3/0.8] Concentration (4)
40- 40 A1 --- YSO? [YN?] Core has an associated protostar?
42- 46 F5.3 km/s sigma [0.1/1.2] Mean velocity dispersion (5)
48- 52 F5.3 km/s e_sigma [0/0.08] Formal error in sigma-obs
54- 58 F5.3 km/s s_sigma [0.005/0.3] Weighted standard deviation
of sigma
60- 63 F4.1 K Tkin [11.3/29.3] Mean kinetic temperature (5)
65- 67 F3.1 K e_Tkin [0/6] Formal error in Tkin
69- 71 F3.1 K s_Tkin [0/7.1] Weighted standard deviation of Tkin
73- 75 F3.1 [K/cm3] log(Pc) [6.5/7.5] Estimated pressure, log (Pc/kB)
77- 83 E7.5 --- Vir [0.1/75] Virial ratio,
-(ΩG+ΩP/c)/2ΩK
85- 91 E7.5 --- G/K [0.004/2.6] Gravitational vs thermal pressure,
-ΩG/ΩK
93- 99 E7.5 --- G/Pc [/20] Core confinement ratio,
ΩG/ΩP,c
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Note (1): Cores taken from the "getsources" catalog discussed in
Lane et al. (2016ApJ...833...44L 2016ApJ...833...44L)
Note (2): Estimated using Equation 1 (this paper) from the total flux.
Note (3): Geometric mean of the major and minor axis lengths.
Note (4): As derived using equation 11 (this paper).
Note (5): Value reported for each quantity is the mean weighted by the inverse
square of the uncertainty, averaging over all core pixels where sufficient
signal was present.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-May-2018