J/ApJ/897/53 IR dark clouds parameters in molecular clouds (Retes-Romero+, 2020) ================================================================================ Infrared Dark Clouds and High-mass Star Formation Activity in Galactic Molecular Clouds. Retes-Romero R., Mayya Y.D., Luna A., Carrasco L. =2020ApJ...897...53R ================================================================================ ADC_Keywords: Interstellar medium; Star Forming Region; YSOs; Molecular clouds Keywords: Interstellar medium ; Infrared dark clouds ; Star formation ; Young stellar objects ; Protostars ; Protoclusters Abstract: Ever since their discovery, infrared dark clouds (IRDCs) are generally considered to be the sites just at the onset of high-mass (HM) star formation. In recent years, it has been realized that not all IRDCs harbor HM young stellar objects (YSOs). Only those IRDCs satisfying a certain mass-size criterion, or equivalently above a certain threshold density, are found to contain HMYSOs. In all cases, IRDCs provide ideal conditions for the formation of stellar clusters. In this paper, we study the massive stellar content of IRDCs to readdress the relation between IRDCs and HM star formation. For this purpose, we have identified all IRDCs associated with a sample of 12 Galactic molecular clouds (MCs). The selected MCs have been the target of a systematic search for YSOs in an earlier study. The cataloged positions of YSOs have been used to search all YSOs embedded in each identified IRDC. In total, we have found 834 YSOs in 128 IRDCs. The sample of IRDCs have mean surface densities of 319M{odot}/pc^2^, mean mass of 1062M{odot}, and a mass function power-law slope -1.8, which are similar to the corresponding properties for the full sample of IRDCs and resulting physical properties in previous studies. We find that all those IRDCs containing at least one intermediate to HM young star satisfy the often-used mass-size criterion for forming HM stars. However, not all IRDCs satisfying the mass-size criterion contain HM stars. We find that the often-used mass-size criterion corresponds to 35% probability of an IRDC forming a massive star. Twenty-five (20%) of the IRDCs are potential sites of stellar clusters of mass more than 100M{odot}. Description: The sample of infrared dark clouds (IRDCs) in the present study consists of all those associated with the 12 molecular clouds (MCs) studied by Retes-Romero+, 2017, J/ApJ/839/113 (R17), and are drawn from the Peretto & Fuller, 2009, J/A+A/505/405 IRDC catalog (hereafter PF09). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 80 12 Summary of the properties of the MC sample where IRDCs have been searched table2.dat 145 128 Observed and derivated parameters of individual IRDCs -------------------------------------------------------------------------------- See also: J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994) J/A+AS/115/81 : A CS(2-1) survey of UC HII regions (Bronfman+, 1996) J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997) J/A+A/426/97 : SIMBA survey. 1.2-mm/IRAS sources (Faundez+, 2004) J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006) J/ApJ/653/1325 : Galactic distribution of infrared dark clouds (Simon+, 2006) J/A+A/462/L17 : Dense cores in interstellar molecular clouds (Alves+, 2007) J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009) J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009) J/ApJ/698/324 : Spitzer IRDCs (Ragan+, 2009) J/ApJ/699/1153 : Kinematic distances GRS molecular clouds (Roman-Duval+, 2009) J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010) J/A+A/533/A109 : Pisa pre-main sequence tracks and isochrones (Tognelli+, 2011) J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012) J/A+A/559/A79 : IRDC APEX/SABOCA observations (Ragan+, 2013) J/A+A/588/A29 : Star formation in massive clumps in Milky Way (Heyer+, 2016) J/ApJ/822/59 : BGPS. XIV. Molecular cloud clumps GBT obs. (Svoboda+, 2016) J/ApJ/839/113 : Molecular clouds with GLIMPSE/MIPSGAL (Retes-Romero+, 2017) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- MC Name of the molecular cloud 6- 15 A10 --- IRAS Name of the principal IRAS source in the MC 17- 21 F5.2 deg GLON [16.94/50.28] Galactic longitude 23- 27 F5.2 deg GLAT [-0.61/0.15] Galactic latitude 29- 31 F3.1 kpc Dist [1.0/5.4] Kinematical distance (1) 33- 35 F3.1 kpc e_Dist [0.1/0.6] Uncertainty in Dist; 12% of value 37- 41 F5.2 Msun Mass [0.23/13.52] Mass of the MC obtained using the LTE method 43- 46 F4.2 Msun e_Mass [0.11/6.46] Uncertainty in Mass 48- 50 I3 --- Nyso [14/861] Number, YSOs spatially associated to the MC 52- 53 I2 --- Nirdc [1/25] Number, IRDCs spatially associated to the MC 55- 57 I3 Msun/pc2 Sgas [133/816] Surface gas density of the MC 59- 61 I3 Msun/pc2 e_Sgas [60/410] Uncertainty in Sgas 63- 66 F4.1 Msun/Myr/pc2 Ssfr [1.0/26.8] Surface density of star formation rate of the MC 68- 71 F4.1 Msun/Myr/pc2 e_Ssfr [0.6/13.5] Uncertainty in Ssfr 73- 76 F4.1 % SFE [0.5/11.9] Star formation efficiency in % units in each cloud. 78- 80 F3.1 % e_SFE [0.1/0.7] Uncertainty in SFE ------------------------------------------------------------------------------- Note (1): Kinematical distance (with an error of 12%) to the dense clump associated to the IRAS source from Faundez+, 2004, J/A+A/426/97. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- MC Name of the molecular cloud 6- 11 A6 --- IRDC IRDC identifier 13- 19 F7.4 deg GLON [16.91/50.43] Galactic longitude, IRDC centroid (1) 21- 27 F7.4 deg GLAT [-0.69/0.24] Galactic latitude, IRDC centroid (1) 29- 36 F8.4 arcsec maj [6.0/361.5] Major axis size of IRDC (1) 38- 45 F8.4 arcsec min [4.3/123.4] Minor axis size of IRDC (1) 47- 54 F8.4 deg PA [-88.0/332.0] Position angle of IRDC (1) 56- 61 F6.4 --- tau [0.37/0.85] mean opacity, Spitzer/IRAC 8um band (1) 63- 69 F7.4 pc2 Area [0.006/54.2] Area of IRDC (2) 71- 77 F7.4 pc2 e_Area [0.001/13.6] Uncertainty in Area 79- 84 F6.4 pc Rad [0.04/4.16] Effective radius of IRDC (2) 86- 91 F6.4 pc e_Rad [0.003/0.3] Uncertainty in Rad 93-102 F10.4 Msun Mass [2/19702] Mass of the IRDC (2) 104-112 F9.4 Msun e_Mass [1/2168] Uncertainty in Mass 114-121 F8.4 Msun/pc2 Sgas [236/543] Surface gas density of IRDC (2) 123-129 F7.4 Msun/pc2 e_Sgas [25.99/59.8] Uncertainty in Sgas 131-137 F7.4 Msun/Myr/pc2 Ssfr [0.013/34.8] Surface density of the star formation rate of the IRDC (2) 139-145 F7.4 Msun/Myr/pc2 e_Ssfr [0.005/13.6] Uncertainty in Ssfr -------------------------------------------------------------------------------- Note (1): Values from Peretto & Fuller, 2009, J/A+A/505/405 Note (2): Values derived in this work -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Coralie Fix [CDS], 27-Sep-2021