J/ApJ/872/121 Molecular cloud cores in the GC 50km/s cloud (Uehara+, 2019)
Molecular cloud cores in the Galactic center 50km/s molecular cloud.
Uehara K., Tsuboi M., Kitamura Y., Miyawaki R., Miyazaki A.
<Astrophys. J., 872, 121 (2019)>
=2019ApJ...872..121U 2019ApJ...872..121U
ADC_Keywords: Molecular clouds; Galactic center; Interstellar medium;
Interferometry; Radio lines
Keywords: Galaxy: center ; ISM: clouds ; ISM: molecules ; stars: formation
Abstract:
The Galactic center 50km/s molecular cloud (50MC) is the most
remarkable molecular cloud in the Sagittarius A region. This cloud is
a candidate for the massive star formation induced by cloud-cloud
collision (CCC) with a collision velocity of ∼30km/s that is estimated
from the velocity dispersion. We observed the whole of the 50MC with a
high angular resolution (∼2.0"x1.4") in Atacama Large
Millimeter/submillimeter Array cycle 1 in the H13CO+ J=1-0 and
C34S J=2-1 emission lines. We identified 241 and 129 bound cores
with a virial parameter of less than 2, which are thought to be
gravitationally bound, in the H13CO+ and C34S maps using the
clumpfind algorithm, respectively. In the CCC region, the bound
H13CO+ and C34S cores are 119 and 82, whose masses are 68% and
76% of those in the whole 50MC, respectively. The distribution of the
core number and column densities in the CCC are biased to larger
densities than those in the non-CCC region. The distributions indicate
that the CCC compresses the molecular gas and increases the number of
the dense bound cores. Additionally, the massive bound cores with
masses of >3000M☉ exist only in the CCC region, although the
slope of the core mass function (CMF) in the CCC region is not
different from that in the non-CCC region. We conclude that the
compression by the CCC efficiently formed massive bound cores even if
the slope of the CMF is not changed so much by the CCC.
Description:
We observed the 50MC located at GLON=-0.018,GLAT=-0.072 as an ALMA
cycle 1 program using the 12m array, Atacama Compact Array (ACA), and
Total Power telescope (TP) on 2013 May 31 to 2015 January 23
(2012.1.00080.S; PI: M. Tsuboi).
We created the channel maps of the H13CO+ J=1-0 (v=86.754GHz) and
C34S J=2-1 (v=96.413GHz) emission lines. The angular resolution of
the H13CO+ J=1-0 map is 2.04"x1.41" at PA=_39.40°,
corresponding to 0.083pcx0.058pc at the distance to the Galactic
center (8.5kpc), and that of the C34S J=2-1 map is 2.00"x1.35"
(0.056pcx0.082pc) at PA=-30.3°.
Objects:
----------------------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------------------
17 45 50.4 -28 59 06 50km/s molecular cloud = GCM +0.02 -0.05
----------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 87 3293 The property of identified molecular cloud cores
in the H13CO+ J=1-0 emission line
table4.dat 87 3192 The property of identified molecular cloud cores
in the C34S J=2-1 emission line
--------------------------------------------------------------------------------
See also:
J/ApJ/428/693 : Rosette Nebula and Maddalena Cloud structures (Williams+ 1994)
J/ApJ/665/1194 : Dense cores in the Orion A cloud survey (Ikeda+, 2007)
J/ApJ/691/1560 : Dense core survey in the Orion B cloud (Ikeda+, 2009)
J/ApJ/702/178 : YSOs in the central 400pc of the Galaxy (Yusef-Zadeh+, 2009)
J/PASJ/67/90 : Central Molecular Zone in H13CO+ (Tsuboi+, 2015)
J/A+A/588/A131 : Warm ISM in the Sagittarius A Complex (Garcia+, 2016)
J/A+A/603/A68 : Images of molecular & ionized gas around Sgr A* (Moser+, 2017)
J/ApJS/244/35 : VLA observations of the Central Molecular Zone (Lu+, 2019)
Byte-by-byte Description of file: table[34].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/3293] Sequential running number
6- 8 A3 --- Subset Subset flag(s) (1)
10- 16 F7.4 deg GLON [-0.05/0.018] Galactic longitude of
the core position (2)
18- 24 F7.4 deg GLAT [-0.12/-0.04] Galactic latitude of
the core position (2)
26- 27 I2 km/s Vlsr [2/94] LSR velocity of the core (2)
29- 33 F5.3 pc Rad [0.04/0.4] Core radius
35- 38 F4.1 km/s dV [2/22] Core FWHM velocity width
40- 43 F4.2 K Tpeak [0.5/4] Peak temperature of the core
45- 50 F6.2 10+2Msun Mvir [0.76/230] Virial mass
52- 57 F6.3 10+2Msun Mlte [0.02/55] LTE mass
59- 64 F6.2 --- alpha [0.4/800] virial parameter, α
66- 71 F6.3 10+5cm-3 nd [0.05/25] Mean number density
73- 79 F7.3 10+8K/cm3 pek/kB [-11/120] Required external pressure
81- 87 A7 --- CCC Is located in the cloud-cloud collision
(CCC) region or not (non-CCC)
--------------------------------------------------------------------------------
Note (1): Subset flag as follows:
1 = The bound cores;
2 = The bound cores identified both in the H13CO+ J=1-0 and
C34S J=2-1 emission lines.
Note (2): The position and Vlsr of each core are those of the most intense
pixel with TB,peak in the core.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 04-Aug-2020